Evolution is instinctual and unstoppable. Just when you think the zenith has been reached, something clicks and the breed gets better. The turbocharger had been lingering in plateau mode until Borg Warner changed the game at the 2010 SEMA Show with its EFR line of highly innovative turbochargers. More revolution than evolution, Borg Warner engineers have literally reinvented the wheel and, with the EFR’s clever integration design, taken the turbo to never-before-seen levels.

83S75 Compressor Map

REINVENTING THE WHEEL

The EFR features trick titanium-aluminide turbine wheels. This highly advanced, extremely difficult to cast alloy results in turbine wheels that are roughly half the weight of the typical inconel turbine wheel. This reduction conjures improved low-end response, higher boost levels at lower engine speeds, and higher wheel speeds. On the cold side, forged aluminum, fully milled wheels pump out the boost. And with Borg Warner’s Extended Tip Technology, aerodynamic optimization efficiency in all areas is improved. The EFR line features compressor wheels ranging from 62mm to 91mm.

INTEGRATE, ASSIMILATE, INCORPORATE

Borg Warner has changed the game further by incorporating ancillary turbo system components into the body of the turbo. The hardest hitting of these integrations are compressor recirculation valve (CRV) ports and mounting. The CRV is plumbed to the low-pressure area, just before the compressor housing, which helps keep the turbine wheel spinning between gears.

The CRV will allow users who need a traditional blow-off valve to simply install a valve and a boost line, eliminating the tedious task of bung welding from the equation. The CRV does expand the turbo’s dimensions and in applications where it causes fitment problems, Borg Warner offers a close-off plate that eliminates the CRV.

EFR turbos are also fitted with integrated boost control solenoid mounting pads and optional integrated wastegates to further streamline the installation process. Borg Warner uses swivel-valve style wastegates available in three different canister/spring combinations with 31mm or 36mm ports. Lastly, each EFR turbo has a pilot hole for a wheel speed sensor probe predrilled.

On the Sierra Sierra Enterprises Lancer Evo time attack car

Borg Warner fashions the EFR turbine housing out of cast stainless steel, a material that provides the benefits of low weight, excellent crack resistance, and smooth inner surfaces but requires intricate investment casting techniques. The big accomplishment here is optimizing the casting process to handle mass production.

PROS AND CONS

Geoff Racier of Full-Race has been in on the development of the EFR line. He has been holed-up fabricating EFR kits and knows more about their real-world capabilities than anyone else. Here are some of his quick insights.

Pros:

• Ultra light gamma-Ti turbine wheel improves spool-up

• Advanced compressor and turbine wheel blade aero (Borg Warner Extended Tip Technology)

• Dual Row Ceramic Ball bearing w/ M50 races and metal bearing cage

• Does not require an external BOV or wastegate (application specific)

• High boost setups still have the option for external wastegates

• Multiple A/R ratios to choose from, and all B2 turbos are easy to change from twin-scroll to single-scroll

Cons:

• The bearings are extremely robust and strong, so this also means BIG. Hence the length of the turbos makes it difficult to fit in some custom applications with transverse engines and air conditioning (ie: B/D/H series Honda, Evos, VW, etc)

• Most existing turbo manifolds are not compatible with EFR turbos, so you may need to purchase an EFR-specific manifold if retrofitting an older turbo kit

FULL RACE KITS

Full Race is ahead of the game, developing kits before EFR production has hit full stride. Applications currently in the Full Race development pipeline and slated for March release include Mitsubishi Evo X, Porsche 996/997, Honda S2000, Honda CRZ, and Subaru WRX/STI.

SR20DET with EFR turbo

The Subie kit will be offered in single-scroll and twin-scroll configuration. “This kit spools faster and generates more torque and midrange power than a single-scroll,” says Full Race’s Geoff Racier. “It’s based on the Full Race twin-scroll lower manifold/twin-scroll up pipe set-up that has long been proven on the track and is used by GST’s legendary time attack Subaru, as well as Yimisport’s STi. For an autocross application, the 7064 will give the fastest spool and response. For a street or weekend track car set-up, we recommend a twin-scroll 7670. For a dedicated time attack build, the 8374 makes a lot of sense. We recommend the 9180 for drag racing.”

“The single-scroll Subaru is designed to be an affordable way to put an EFR turbo on your Subaru,” relates Racier. “It uses the stock lower manifold, or any aftermarket two-bolt lower. A single-scroll EFR 7670 or 7064 is the call here. If you already have a rotated T3 kit and want to put an EFR turbo on without changing your header or old setup much, this is a good way to do that. This kit holds the turbo in the same location as our twin-scroll kit, so it can easily be upgraded to a twin-scroll set-up later on by simply swapping the hot-side components.”

The EFR has great potential. Tuners can use larger wheels and housings without paying the piper on the spool-up and top wheel speed fronts – which is always a good thing. The EFR is much more than a turbo; it incorporates other turbo system components and features tip-of-the-spear technologies in wheel and housing designs, which should be remembered when comparing prices to the proverbial eBay special turbo. How much of a game-changer will the EFR turbo be? We are not sure yet without conclusive back-to-back dyno testing but the potential is certainly eye opening.

SOURCES
Borg Warner Turbo Systems
www.borgwarnerboosted.com

Full-Race
(602) 437-2101
www.full-race.com

Borg Warner EFR Turbocharger

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Throughout the years, there have been various engine oil additives that have had claims of increased engine power or better gas mileage. Everyone knows that some products are simply gimmicks that only apply to primitive engines, ones that are designed inefficiently from the factory in the very beginning. These manufacturers are now very careful in how their products are represented, taking special care not to mislead consumers by using false claims in their advertising. But how will an engine oil additive, that supposedly contains modern NASA technology, adopt to a commercialized automobile powerplant?

Fresh oil change before testing the RAN UP

That was the claim behind RSR’s RAN UP oil additive; one that we had to put to the test.

As RSR tells it, nano technology is basically a dispersion of certain elements to a nano scale level by lasers and chemical reaction methods. Enthusiasts in the automobile industry may be familiar with ceramic applications, such as HPC coating and its high heat barrier characteristics, but the base ceramic element also serves a different benefit when broken down to a smaller nano scale particle form. NASA has utilized this ceramic powder technology in their robotics field as a substitute for lubrication, since liquid forms are not compatible in space. It may sound cliché, but it’s literally modern space age technology.

RAN UP

Tuning parts manufacturer RSR has just released their engine oil additive, called RAN UP, containing this modern nano-ceramic technology in a powder and liquid mixture form. In appearance, RAN UP is similar to milk. The ceramic particles, with a high dispersion rate, mix very well with the engine’s oil and are able to get inside the rotating metal components to reduce frictional energy loss. Nano particles are smaller than the standard flu virus, and can even be compared to the size of a human cell.

Supercharged 2003 Ford Mustang Cobra test car

For immediate results, RAN UP can be applied to any kind of engine that has a high vibration rate such as air tools, compressors, motorboats, and motorcycles. It’s not entirely new to the motorsports industry; RSR claims that some Super GT cars have been using it in Japan for some time now. Of course, the RSR team has also adopted the juice in their Formula D Scion tC’s turbocharged race engine all season long. RSR claims these benefits:

• Increased engine power and torque output
• Increased response
• Decreased engine noise and vibration
• Extends engine oil change intervals
• Promotes fuel efficiency
• Reduces C02 emissions output

THE TEST

To reveal the true nature of the RAN UP ingredients and its effects on an engine, we teamed up with SR Motorcars of Gardena, California to perform a comparison test on their two-wheel drive dynamometer. A supercharged 2003 Ford Mustang Cobra was chosen as the test vehicle, lightly modified with bolt-ons. Due for an oil change, our plan was to baseline the car on its old oil, dyno right after an oil change (to show the effect of fresh oil), and then dyno after adding in the RAN UP (to show the difference the additive made).

Our Cobra’s first baseline (using old oil, due for a change) logged in at 445.41 HP and 446.07 lb/ft of torque via Dynojet. After changing the oil, we ended up with 440.66 HP and 444.40 lb//ft of torque. We were surprised to see a large 4.75whp loss but multiple runs proved consistent in the results.

For the test to remain as neutral and fair as possible a controlled environment was created, attempting to standardize such variables as the starting outside air temp, humidity, engine operating temp, and supercharger surface temps for the back-to-back pulls.

The RAN UP additive was simply added to the crankcase of the 4.6 liter V8 following the baseline power tests. RSR did recommend that the RAN UP be shaken thoroughly before being added, to stir up all particles, and that the receiving car be given a 30-minute break-in with RAN UP added for maximum results. This allows the RAN UP additive to filter throughout the engine. With a 4.6-liter displacement, the Cobra was given two bottles of RAN UP. RSR recommends one bottle for 2.0-liter range four-cylinder compacts and two bottles or more for larger V8 engines.

RESULTS

The result presented some astonishing numbers, a 12.91 HP increase and 11.26 lb/ft of torque improvement. A 12whp gain may not seem to be a substantial gain to some folks but in the world of motorsports, a few horsepower can potentially mean the difference between a podium finish and a loss. This is especially important for drag racers, club racers, or autocrossers, who are all looking for easy, undetectable gains in power. Considering the environmental factors were kept similar for the comparison, these numbers are pretty solid. Also, according to the owner’s testimonial, the Mustang’s engine seemed quieter and smoother in operation during a real world test drive.

The results can clearly be seen on the dyno graph. The power and torque output is increased consistently throughout each powerband.

The MSRP for a bottle is still pending, but since it costs about 6,500 yen in Japan, the US price can be anywhere from $50 to $100 per bottle. We realize that this product won’t be for everyone, especially when you factor in the price and the fact that regular additions are necessary with oil changes. But for the racer who needs every edge that he can, stealthily gaining 13hp without breaking out the toolbox is always worth something.

SOURCES
RSR USA
130 E. Dyer Rd.
Santa Ana, CA 92707
(714) 424-0686
http://www.rs-r.com

SR Motorcars
115 E. Gardena Blvd, Suite 1A
Gardena, CA 90248
(310) 516-1003
http://www.srmotorcars.com

RSR RAN UP Oil Additive Dyno Test

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When discussing the spool-up and high-end flow characteristics of a given turbocharger, the term “wheel trim” may pop up. If you’re in the market for a turbocharger upgrade, comparing new units, or are planning your own backyard DIY turbo kit, you’re bound to run across wheel trim.

It’s a real term and its mission is to establish the relative size of a compressor (cold/intake side) or turbine wheel (hot/exhaust side). In simpler dummy-like terms, a turbo wheel is the blade-like spinning fan inside a turbocharger. The turbine wheel is spun by exhaust gases and is connected to the compressor wheel, which compresses (duh – Ed.) intake air for the engine.

The often-overlooked aspect of this term is that it is used to compare wheels within the same turbo family. So the trim size can be, and often is, mistakenly used for comparison between turbo families.

Some turbo manufacturers, such as Turbonetics, have inserted extra letter designations into their turbo line-up. Turbonetics’ GT-K turbo series has P-trim and S-trim designations and its T3/T4 lineup has Stage I, Stage II, and Stage III trims. Such designations camouflage the numeric value of wheel trim and often add to the confusion that surrounds the term.

TRIM MATH

First, understanding the mathematical calculation that creates the wheel trim number will help us crystallize the meaning of the term.

Trim = Inducer diameter divided by outer diameter, squared, and multiplied by 100

or

(in / out) ² x 100

So a compressor (cold/intake side) wheel with an inducer measurement of 51.7mm and an outer/exducer of 76mm is calculated like this: 51.7 divided by 76 = .6802631. Then .6802631 squared = .4627578. Multiply that by 100 and you get 46.27578 or 46-Trim. Easy, right?

Plugging in numbers is meaningless though unless one knows the turbo family’s entire range of wheel trims. In this case, the 46-trim wheel is from the T04E family. There are four wheel trims offered for the T04E – 46, 50, 57 and 60. The bigger the trim, the more the wheel will flow but it does so at a slight loss in efficiency. It should be noted that this comparison is within the T04E family and the compressor housing A/R ratio needs to remain constant.

The difference in flow has to do with the blade speed but issues such as the blade contour, swept angle, and surface area of the blades also impact the overall flow characteristics of the wheel in question.

When it comes to compressor wheel selection, lean towards a large trim rating in a smaller wheel instead of going to a larger wheel. Larger wheels are heavier and rotational weight equals lag.

TURBO TUNING

Basically, wheel trim is a fine tuning element once you have determined the proper turbo family for your application. Turbo proprietors often rate turbos by horsepower or flow (in cfm).

We find the cfm rating much better because it is easier to quantify. Will a 600hp turbo make 600hp with both a 2.0-liter four cylinder and a big block V8? We don’t think so. The use of a compressor map to pinpoint the flow characteristics is always the best way to go.

The turbine side (hot/exhaust side) of the wheel trim equation is a much murkier proposition. The calculations are non-issues because the manufacturers have kept their turbine wheel maps under wraps, making them harder to find than satisfied GM shareholders. Experience from the manufacturer, tuner, or fellow enthusiasts is the best bet. Luckily, wheel trim is not as critical to turbo performance as the compressor wheel selection.

A/R RATIO

In fact, on the hot side, the A/R ratio of the turbine housing is far more important as it dictates spool-up time, backpressure, maximum flow capabilities, and the part throttle responsiveness of the entire unit. The turbine housing can be swapped for a bigger or smaller size to optimize hot-side performance, whereas the turbine wheel is not interchangeable.

Area/Radius (A/R) Ratio is a numeric reflection of the size of a given housing gleaned from an equation that divides the area at a point in the housing by the point’s radius as measured from the shaft of the wheel.

The area of A/R is the area at a given point within the housing, where the compressed air moves from the inlet to the nozzle. The radius of A/R is multiple points measured from the shaft center to positions on the housing.

The formula takes all the area measurements and divides them by their corresponding radius measurements.

A1/R1=A2/R2=A3/R3=A4/R4 and so on

or

Area/Radius=Constant

While compressor housings have A/R ratios the measurement is most important on the turbine side of the turbo. The size of the turbine housing will be critical in determining the responsiveness and/or top-end flow of the turbocharger.

A responsive unit will have a lower A/R [.63, .78, etc] and will spool-up quickly but will sacrifice maximum flow and possibly cause backpressure in the system. Conversely, a big A/R housing [.93, 1.12, etc] will sacrifice responsiveness in order to flow more volume at the top end.

It is always best to go with tried and true turbo kits and choices that have proven track records in regards to power output and spool-up characteristics.

But it is still good to know the down-and-dirty details so you can make informed decisions, especially when you upgrade to a custom off-the-grid turbo or find yourself as the only person on Earth looking to turbocharge a Camry the right way.

Sources

Turbonetics
www.turboneticsinc.com

Tomei
www.tomeiusa.com

Garrett
www.turbobygarrett.com

After months of mental hopscotch you finally decide to go for the gold and turbocharge your car. You plan to hit it hard and do it right. Doing it right, of course, should include swapping to a turbo boost-capable piston.

There is a good deal of engineering attention showered on pistons, especially those specifically designed for turbocharged engines. Most turbo pistons provide a lower static compression ratio (about 8.5:1 to 9.0:1) than your OEM piston. Piston manufacturers will lower the compression ratio by adding a dish to the crown of the piston.

In addition, ring locations and crown thicknesses are adjusted to handle the increased stress brought on by forced induction. For most high horsepower applications, including turbocharging, forged pistons are recommended. OEM pistons, especially those in naturally aspirated engines, are usually cast to reduce manufacturing cost and machining time but lack the strength, design and compression ratio required to turbocharge your engine in a safe, reliable and power worthy fashion.

Almost all forged aftermarket pistons are manufactured from either 4032 or 2618 aluminum alloy. Both alloys have advantages and disadvantages depending on the application. Racing engines usually require the stronger low-silicon 2618 alloy, while less demanding applications favor the greater silicon content and tighter clearances of 4032 alloy.

If you’re looking for the strongest piston available, 2618 is right for you. Most racing engines use 2618 alloy exclusively. The primary disadvantage of 2618 is that it requires more initial piston-to-cylinder wall clearance so your engine may be a bit noisy when cold.

Wrist pins are another factor to consider. Wrist pins are probably the most overlooked component in the piston assembly. Wrist pins transfer the force between the piston and the connecting rod. This stress is very significant at the end of the compression stroke and beginning of the power stroke. It is important to select a wrist pin with sufficient wall thickness for your application.

A turbocharged engine will required a thicker wrist pin than a comparable naturally aspirated engine. Four cylinder engines with over 500hp should be using a wrist pin with a minimum of .170-inch of wall thickness. For higher horsepower and street applications, over .200-inch is recommended.

Other factors to consider in the proper selection and installation of turbo pistons include:

Piston-To-Cylinder Wall Clearance

Piston-to-cylinder wall clearance is the distance between the piston skirt and cylinder wall of the block. You can calculate this clearance by subtracting the piston skirt measurement (at the gauge point specified by the manufacturer) from the finished bore size. The amount of clearance needed depends on the bore size and application. Good piston manufacturers will include a spec sheet with their recommended clearance in the box.

Ring End Gap

The amount of piston ring end gap required depends on the ring material and engine application. Basically, the more heat, the larger the end gap. Turbocharged engines subject the piston and rings to more heat than naturally aspirated engines so more end gap is necessary. Insufficient ring end gap will lead to contact between the ends of the rings. This can damage the rings, cylinder wall, and pistons and potentially destroy your engine. When in doubt, call the ring manufacturer.

Piston-To-Valve Clearance

Piston-to-valve clearance is determined by cam lift, lobe separation, duration, valve margin, head design and milling of the cylinder head. Most aftermarket pistons are made with generous valve reliefs that are compatible with aftermarket cams.

However, always check your piston to valve clearance to be safe. This can be done by placing modeling clay on the crown of the piston, test assembling and then rotating over the engine. Minimum recommended clearance is around .100-inch on the intake and exhaust.

Deck Clearance

This is simple – don’t let the piston hit the head. Around .040-inch clearance or more is usually safe for engines with steel rods. Deck clearance is also important when trying to achieve a piston’s advertised compression ratio. More deck clearance equals a lower compression ratio.

Rod Bolt Stretch

Measuring rod bolt stretch is the most accurate method when torquing rod bolts. Rather than measuring torque, which is effected by friction and torque wrench calibration, you measure the amount the bolt has stretched before and after you have tightened it. The amount of stretch will tell you how much preload is applied between the rod and rod cap. Connecting rod and rod bolt manufacturers can provide you with their recommended stretch.

As always, when upgrading or building any engine, proper planning is key and investing in a set of aftermarket forged turbo pistons is wise. These new pistons’ reliability factor will bring peace of mind every time your boost gauge spikes and your tach arches for redline.

Sources
JE Pistons
www.jepistons.com

Tomei
www.tomeiusa.com

Cosworth
www.cosworthusa.com

Mahle
www.mahleclevite.com

Wiseco
www.wiseco.com

One of the most overlooked areas in project cars is the drivetrain. When you’re hammering through the gears at the track, the clutch under your left foot and the lever in your right hand matter as much as anything else. Put together a good system and you’ll be too busy chasing short straights and tightening turns to notice anything else. Drop in a few pieces of junk and you’ll be cursing the imprecise feel and shocking engagement as you careen off the road.

The Holy Grail for SR20DET owners is a true six-speed transmission. The promise of shorter gearing and an overdrive 6^th for freeway cruising is sometimes just too good to pass up. But most of the six-speed options for the SR20DET aren’t a direct drop in, requiring custom parts or lots of parts swapping.

The previous best option was to swap in the stock six-speed transmission from a S15 Silvia Spec R or one of the special six-speed Autech S15 Silvias.

But that route has its own issues, as the S15 six-speed doesn’t have a mechanical speedometer drive gear inside the transmission casing like the five-speed S13, S14, and S15 Spec S models do. Enter Nismo.

Short for Nissan Motorsports International Co., Ltd., Nismo is the tuning and racing arm of Nissan Japan. From within their Tokyo headquarters, Nismo maintains a Super GT GT500-class program and produces some of the most extensively engineered and tested aftermarket go-fast parts. This includes camshafts, reinforced oil pumps, suspension arms, brakes, limited-slip differentials, and a reinforced drop-in six-speed transmission for SR20DET equipped S13, S14, or S15 owners.

Required – S15 Clutch Kit

The first thing that you should be aware of when attempting this particular swap is the price. The transmission itself doesn’t come cheap (it retails roughly around the $4,000 mark last we checked – Ed.) and if you own a S13 or S14, you’ll have to source a S15 clutch kit due to the difference in depth and transmission input shaft length. Trust us, your busted old S13 clutch won’t work here. With our test car being a S13, we sourced a S15 Silvia application Nismo Coppermix clutch kit.

The single plate Coppermix clutch is rated to hold 391 lb-ft of torque and engages lightly and easily. It’s also 1.4-lbs lighter than the factory SR20DET clutch. The Nismo Coppermix aluminum flywheel is 3.3-lbs lighter than stock for a reduction in rotating mass but the most important thing about our clutch kit is its S15 fitment.

Nismo Reinforced Six-Speed Transmission

The S15 Spec R picks up its speedometer signal electronically from the rear ABS sensor and a S15 six-speed transmission swap necessitates a swap to the rear S15 pumpkin and lots of custom wiring to get the S15 gauge cluster to work (the S13 and S14 gauge clusters will not read the S15 speedo signal). So, unless you don’t care how fast you’re going down the street, a S15 six-speed transmission is not a direct bolt in into any USDM 240SX.

S15 clutch required

Starting with the FS6R92A S15 six-speed transmission casing, Nismo fits a custom reinforced gearset and adds a mechanical speedometer drive gear to the mix. Tomei USA also sells the separate Nismo bolt-in kit, which includes the transmission mount, driveshaft, shifter, hardware and required harness extensions.

The only other items you’ll need are the previously mentioned S15 clutch, new shift knob (five-speeds use a 10×1.25 thread, six-speeds are 12×1.25), and gear oil. Unhappy with all the burning hot aluminum and titanium shift knobs on the market, we had our rubber Nissan shift knob machined out to 12mm.

Nismo offers the reinforced six-speed transmission with a multitude of kits to make it a direct drop-in into any S13, S14, or S15 equipped with a SR20DET or SR20DE engine. If you own a S13 or S14, the S15 flywheel, pressure plate, and clutch will bolt directly to any SR20DET engine.

We paid a visit to Steve Rodgers at SR Motorcars in Gardena, California and swapped out our tired five-speed transmission in less than half a day. Rodgers knows the S-chassis and SR20DET engine inside and out and made short work of the installation after lifting the transmission into place with a Herculean effort.

3.8-lbs lighter with 1 more gear

We were pleasantly surprised to discover just how simple Nismo has made this six-speed swap. All parts are labeled and separately bagged and have perfect clearances. The included driveshaft was the perfect length and had zero balance or vibration issues. After we fired up the car, it was ready to go and the speedometer functioned perfectly. This is what you get with near OEM level engineering.

Because it’s based around a standard S15 six-speed transmission, shifter feel is largely the same as with a stock S15 Silvia Spec R. The throws are quite long for performance use but the precision is what matters and the six-speed shows its strength over the five-speed there.

Shifting is much more precise through the gears and the movement is so smooth, there isn’t any need to force gear changes. Nismo claims to have reinforced this transmission over a stock S15 six-speed through the use of larger diameter gears and by changing most of the gear ratios versus the standard S15 box.

For fifth gear, which is the same as the standard S15 (1.000), Nismo has reduced the number of both counter and main gear teeth and has increased the size of the gear teeth.

The Nismo first gear is noticeably taller (numerically lower), with the new gearing helping to cushion the shock load of a hard launch from a standstill. One of the biggest advantages with the Nismo six-speed though is how 2^nd, 3^rd, and 4^th gear have all been moved closer to each other, which helps us stay above the boost threshold when on track. Combine that with a higher torque capacity and you’ve got yourself a winner.

Contact
Tomei USA
www.tomeiusa.com

TIRE SIZE WIDTH (mm) 225
ASPECT RATIO (%) 45
WHEEL INCH 17
TIRE DIAMETER 634.3

TYPE S13,S14 STD 5-SPEED (FD: 4.83)
1ST 3.321 26.45 (speed at 3k RPM) 44.08 (5k RPM) 57.31 (6.5k RPM) 70.53 (8k RPM)
2ND 1.902 46.18 76.97 100.06 123.15
3RD 1.308 67.14 111.90 145.48 179.05
4TH 1.000 87.85 146.42 190.34 234.26
5TH 0.838 104.86 174.76 227.19 279.62

TYPE S13.S14 NISMO-6SPEED (FD: 4.83)
1ST 2.907 30.22 50.36 65.47 80.58
2ND 1.989 44.17 73.62 95.71 117.79
3RD 1.537 57.15 95.24 123.81 152.39
4TH 1.218 72.13 120.22 156.29 192.35
5Th 1.000 87.85 146.42 190.34 234.26
6TH, 0.862 101.87 169.78 220.71 271.64

TYPE S15 SPEC-R STD-6SPD (FD: 3.692)
1ST 3.624 26.81 44.68 58.08 71.49
2ND 2.200 44.16 73.60 95.68 117.76
3RD 1.541 63.05 105.08 136.60 168.12
4TH 1.213 80.08 133.47 173.51 213.55
5Th 1.000 97.15 161.92 210.50 259.07
6TH 0.767 126.60 211.00 274.30 337.60

TYPE S15 SPEC-R NISMO-6SPD (FD: 3.692)
1ST 2.907 33.42 55.70 72.41 89.12
2ND 1.989 48.85 81.42 105.84 130.27
3RD 1.537 63.20 105.33 136.93 168.53
4TH 1.218 79.77 132.95 172.84 212.72
5TH 1.000 97.15 161.92 210.50 259.07
6TH 0.862 112.65 187.76 244.08 300.41

When it comes to 240SXs, a limited-slip differential is a must. Look at it this way – when a S13 or S14 (or any rear-drive car, really – Ed.) goes around a corner, its rear wheels travel in two different arcs and thus the two wheels are moving at different speeds.

With an open differential, the same amount of torque is distributed to both wheels at all times and as you corner harder and one tire begins to lose traction, that tire will go up in smoke and continue to do so unless you ease off the gas.

As the tire spins into dust, that wheel is exhibiting a much higher wheel speed than the wheel opposite of it. The problem with this is that the non-spinning wheel, the one with grip, will ultimately be fed the same low amount of torque that the spinning wheel is capable of holding.

A limited-slip differential limits the difference in wheel speed between the drive wheels by diverting torque from the spinning wheel over to the non-spinning wheel. This allows you to take advantage of a greater overall level of grip and to play more with the slip angle of the rear tires, allowing a driver to easily play with the balance of the car using the throttle.

For the best balance and power application, you’ll want a LSD that is responsive and provides a smooth, easy breakaway at the limit. For 240SXs, some of the best parts are made by Nissan’s own racing division – Nismo.

Enter the adjustable, clutch-type Nismo GT L.S.D Pro, distributed in the US by engine parts manufacturer Tomei. Clutch-type LSDs work by using springs that apply an “initial torque” to the clutch plates found within the LSD itself.

As one wheel begins to spin more than the other, it locks the clutches together, transferring power to the opposite wheel.  A higher initial torque value or tighter clutch pack will allow less speed differential between the wheels, locking the wheels together sooner. Drifters will often use a higher initial torque value than road racers as they actually want their cars to kick out soon after applying the gas during cornering.

Unique on the market, the GT L.S.D. Pro features an externally adjustable initial torque setting. The standard Nismo GT L.S.D. makes use of 20 clutch plates to help smooth over the locking transition. The GT L.S.D. Pro then adds three grooves of different depth to its pinion mate shaft, which is connected externally to a 19mm head.

By unbolting the right side axle and popping off the stub axle, a ratchet and socket can be inserted to turn the pinion mate shaft left (47.0 lb-ft initial torque), center (61.5 lb-ft), and right (101 lb-ft). With this capability, the LSD can be set trackside to compensate for power, tires or even the difference between a drift day and a track day. This level of fine-tuning, for changes in parts and conditions, is not normally found in a LSD.

SR Motorcars in Gardena, CA handled the Nismo LSD install and it dropped right in without any trouble, although it was all too easy to be found playing with the external adjustment of the LSD. Impressively, the Nismo kit is all-inclusive. In the box was the LSD, fluid, pumpkin cover gasket, side bearings, new ring gear bolts, and axle stubs.

The LSD uses pure synthetic 80W-90 gear oil, which isn’t too common at the local Pep Boys. Be sure to have another jug on hand for a change following initial break-in. Nismo suggests a break-in of 186-miles at no more than 37mph.

The only downside, of course, to a kit of this caliber is the price. There are much cheaper LSDs on the market for the 240SX but these other kits don’t include everything you’ll need and often come with compromises such as noise or poor grabbing characteristics across the clutch faces. Chatter, clanking and noise-free, the GT L.S.D. Pro has proven to be quite the usable street LSD.

We set our GT L.S.D. Pro to the low setting, in order to soften the rear breakaway characteristics for track use, and hit Buttonwillow Raceway in our tester S13 240SX fastback. Our test car was equipped with a 200whp SR20DET, TEIN coilovers, Carbotech XP8 brake pads, and Michelin Pilot Sport Cup tires.

Compared to the test car’s original clutch-type LSD, the Nismo GT L.S.D. Pro was by far smoother on acceleration and provided great feedback to the rear end’s behavior leaving corners. Compared to the OEM viscous LSD, the Nismo GT L.S.D. Pro goes lap after lap, instead of overheating and failing to finish an entire run session. If our car made more power, the difference in endurance and torque handling would be even more immediate.

After trying out the LSD, we have to say that the low setting is highly recommended for all you non-drifters out there, on account of the S13 chassis’ notorious abundance of rear anti-squat geometry. At the higher settings, the LSD will break away sooner on corner exit, making the driver wait longer before being able to hit the gas. Of course, the higher lock also makes it easier to break the rear loose and keep it that way during drifts.

After another 550-miles on the car, we’ve only experienced the slightest of clunking when the car is cold and warming up. But once up to temperature, there is nothing from the LSD but glorious throttle steering. Faster and more fun? Works for us – just be sure to save up those pennies.

Contact
Tomei USA
www.tomeiusa.com

Without a doubt, Formula One is at the forefront of automotive tech engineering. The highly competitive and very expensive racing series needs no introduction here at The Octane Report. We all know that the cars are fast and big dollar.

Intricate aerodynamics, carbon composite rotors, and 18,000rpm 1000hp engines – all are present in F1. The intense technological development in the racecars lends just as much mystique to the series as the casino playboys, airline tycoon team owners, and super model girlfriends. Almost.

The carbon fiber steering wheel alone costs above $40,000 and provides the driver with control over all the intricate computerized systems in the F1 car. This isn’t quite the same as the vinyl steering wheel in your neighbor’s Oldsmobile, Formula One wheels are actually incredibly complex and equally expensive.

Although there is a constant stream of data from the racecar to the pits, which allows the team engineers to monitor the car’s health, only the driver can actually change settings once the car is on the track.

A few years ago, regulations permitted “two-way telemetry”, which allowed data to be sent from the pits to the car (for example, air/fuel mixture changes or traction control changes from dry to wet conditions). However, this has been removed for cost reasons. Now the driver himself has to make any required changes while driving.

The main body of the F1 steering wheel is made from carbon fiber. The hand grips can be trimmed in alcantara (a composite material composed of 68% polyester and 32% polyurethane) or rubber, depending on the preference of the driver. The positioning of the switches is also down to driver choice and each driver will have his own preferred layout.

On race weekends, each driver will have a minimum of three steering wheels available so there is always a spare on hand should there be any issues. That’s more than $120,000 in steering wheels alone.

Each steering wheel is designed and manufactured in-house by the team. The only part outsourced is the display, which is part of the standard electronics package that all teams are required to use. The display can be built into the steering wheel or mounted to the edge of the cockpit itself.

Formula One Steering Wheel Buttons

Shift Lights: The row of lights across the top of the steering wheel shows the RPMs and the optimum shift point.

Gear Number: Shows the driver which gear he is currently in.

Marshall Lights: This cluster of three lights on either side of the display comes on if there is a red flag (race or session stopped), blue flag (a faster driver is lapping you) or yellow flag (incident ahead). These lights are switched on or off by the FIA Race Control and were introduced to help the drivers, who sometimes find it difficult to see the flags waved by the marshals.

Displays: The two display windows on either side of the gear number shows the driver important data such as oil or water temperature. They can also show his lap time and during qualifying, he can see whether he is quicker or slower to a reference lap (normally his fastest lap).

+1/-1: These control the fail-safe software programmed into the car. If the engineers see a problem developing with a system through the telemetry, the driver can switch off or disable the relevant sensor if it is not critical or activate a back-up sensor. The driver uses these buttons to scroll to the relevant mode and then uses the ON/OFF button to enable the mode.

Drink: Activates the drink system to help the driver avoid becoming dehydrated, especially at the hotter circuits.

+10/Start Lights: This button has two functions. The +10 part is linked with the fail-safe modes of the +1/-1 button and allows the driver to ‘fast forward’ to the relevant number by 10 steps. The Start Light function is used during practice sessions when drivers carry out practice starts at the end of the pit lane. He presses this button and the shift lights at the top of the steering wheel simulate the way the lights work at the beginning of the race. The engineers can then analyze reaction times.

O/Take: Can be used when a driver is fighting for position during a race and allows the software to momentarily raise the rev limiter (although not beyond the mandated 18,000rpm limit).

Pit Confirm: The driver presses this button to acknowledge that he has heard the engineer’s call or pit board signal to pit on his current lap. This is useful at circuits where the radio coverage is not good.

Talk: Allows the driver to talk to his engineers over the radio.

BBAL: A shortcut button to show the current brake balance on the display.

REV: The driver can’t select reverse using the normal gear paddles so he has to press this button (at the same time as pulling in a clutch paddle) to put the car into reverse gear.

Rotary Switches: These switches can control a number of functions, which the driver and engineers will define. Each position of each switch subtly changes a particular characteristic of the car, for example a mixture mode, the hydraulic differential, or the torque map of the engine. These switches also come into play if a safety car comes out in the race or if it starts to rain, allowing the driver to tune the car to his liking.

FFA: This allows the driver to adjust the position of the front wing angle. Using this switch (which stands for Front Flap Adjust) moves the front wing, allowing him to adjust the aerodynamic balance.

Mark: If the driver feels something strange with the car at a certain point on track, he can press this button and the engineers can pinpoint the data to analyze the issue.

ON/OFF: Used with the +1/-1 buttons to switch on or off a fail-safe mode.

Neutral: Similarly to the reverse button, the software stops the driver accidentally selecting neutral from the gear paddles. He has to press this button to go to neutral.

Pit Limiter: Enables or disables the pit lane speed limiter. At most races, the speed limit is 60km/h for practice sessions and 100km/h during qualifying and the race. Pressing this button too late (or not pressing it all) can result in the driver receiving a fine in a practice session or a time penalty during the race.

BPF: Stands for Bite Point Find and is used by the engineers to analyze the characteristics of the clutch. This is then fed back to the driver to optimize his driving at the standing start. Now that traction control and launch control are no longer allowed in Formula One, the start of the race has to be completely controlled by the driver, so it’s crucial for him to know how the clutch is going to react.

Like a good set of tires, drivetrain is an often-overlooked area of car tuning. Many obsess over blowers, exhausts and wheels but when it comes time to get that project buttoned up, the cheapest clutch kit is usually shoved in.

Or, more often than not, the stock clutch is pushed to the ragged edge and subjected to 400 lb/ft more torque than it was ever designed for.

Being cheap and getting too light of a clutch is a surefire way to shorten the life of your clutch kit and reduce the efficiency of your car. Besides having to live with poor pedal feel and the possibility that something will go wrong, meaning the transmission will have to be pulled again, using a cheap clutch can actually leave acceleration power on the table. Who wants that?

Remember, all the power in the world is a great thing but it still has to get to the pavement. To complement a high-powered engine, you’ll want a clutch kit that has more than enough holding power, good pedal feel (if driven on the street), smooth engagement and a lighter weight. With all these elements in place, a car can accelerate and decelerate faster using the same amount of power.

The key is the fact that the clutch and flywheel are solidly bolted to the engine’s crankshaft at all times. The clutch and flywheel combo will always spin around at the same RPM that your engine is reading. By pressing in the clutch pedal and moving the gear lever, you’re actually engaging and disengaging the transmission’s input into the engine.

16lbs lighter than stock

It’s simple enough to guess that a lighter clutch and flywheel is easier to spin up to a certain RPM since it weighs less. This is the reason for the massive popularity of lightweight aluminum flywheels; they can get you tenths in the quarter-mile with their reduction in weight.

And since the force required to spin a clutch depends on mass and clutch size, a smaller clutch should also aid with acceleration. It’s the same principle behind using lightweight forged wheels versus big, heavy chrome rims.

Taking rotating mass out of your drivetrain with carbon fiber driveshafts, lightweight clutches and small wheels has been done for years. But to find out how effective it really is we hit the four-wheel dyno at Tuning Technologies in Colton, California.

Alfred, Jen and the TT crew opened up their facility for us to test the SPEC Clutch Mini Twin kit on the M1 Fabrication & Development 2005 Mitsubishi Lancer Evolution VIII. This Evo has seen some heavy track use in NASA Time Trial competition and we decided to test the stock and SPEC clutches back to back. A custom GT30R turbo kit has been fitted to the M1 Evo VIII and 420whp is available at a low boost setting of 22psi.

The SPEC Mini Twin clutch kit offered both of the elements that we were looking to test gains from, a smaller size and a lighter weight. Rated to hold 800 lb/ft of torque, the SPEC clutch kit came with an aluminum flywheel 7lbs lighter than stock (8.5 versus 15.5 lbs) and was 16lbs lighter in total than all the factory parts. This is even counting the SPEC hydraulic throwout bearing that converts the clutch from a pull-type to a push-type for more reliable operation.

With aftermarket clutches there are a few ways to increase holding power and torque capacity but each have their downsides as well. Some of the most common include different friction material (better heat resistance but minimal holding power gains), a stronger pressure plate (stiffer pedal to push down) and swapping to multiple discs (expensive and could be noisy from internal rattling).

The SPEC Mini Twin clutch uses two clutch discs with what is basically another flywheel sandwiched between them. This gives more surface area than just one clutch and thus more holding power with minimal pedal stiffness.

Pedal feel with the SPEC twin-plate clutch is noticeably light and short and the engagement is much sharper than with the factory clutch. Without as much mass on the flywheel to help launch the car, this kit is designed for road racing and track use, not for drag racing.

The clutch needs to be slipped with plenty of revs to keep going and is pretty easy to stall. You get used to it and this unit can be used in a street car but it’s not exactly street friendly with an OEM feel. This is a real racing unit. SPEC does offer more street friendly units but this racing-style clutch is the best option for us to be able to test the difference in rotational mass.

First up, we dyno the GT30R’s fury against the stock clutch setup. This combo has overheated and slipped on track at Buttonwillow Raceway, proving the low capacity of the stock parts. Next, Tuning Technologies completed an amazing 4.5-hour clutch swap. That may seem really long to some of you but remember, this isn’t a Honda Civic. An Evo clutch install is an ordeal and could easily take twice as long.

The SPEC clutch was then given a full solid day of driving for break in and then the M1 Evo was put back on the same dyno. Both dyno runs used the same exact Tuning Technologies ECU tune and boost level. We measured the same exact atmospheric conditions except for a 2-degree F increase in air temp for the SPEC testing.

Dyno testing reveals the time difference required to reach a specific torque out put. The lighter SPEC system is faster past 3,000 rpm.

The results are eye opening, with the lighter and smaller SPEC twin-disc clutch kit allowing the Evo’s engine to rev faster and easier, hitting peak boost and making power sooner. Where the stock parts allow the Evo to reach 300 lb/ft of torque in about 5.2-seconds, the SPEC clutch hits that same amount in only 4.5-seconds. We measured almost a half second difference from stock for the Evo to reach the 350whp mark and once peak boost is reached, the SPEC clutch helps free up power all the way to the top.

It took almost an entire second less for this Evo to reach the 300 lb/ft mark during a single dyno run. Think about when this car goes out for a track session. Imagine how many times the car must enter braking zones, hit apexes and then accelerate out of a corner. Multiply all that acceleration by the time gained here and you’ll see the advantages of reducing rotating weight and having a lightweight clutch.

Races are won or lost by fractions of a second, we have that here already in a single dyno run and this clutch won’t slip at all on track. Sometimes going faster isn’t just about adding power. Sometimes it’s about maximizing what you already have.

Sources
Spec Clutch
(800) 828-4379
www.specclutch.com

Tuning Technologies
(909) 783-1200
www.tuningtechnologies.com

M1 Fabrication & Development
(714) 671-0077
www.m1fd.com

When it comes to cars, heat is the enemy. It robs power, destroys parts, and can make for quite the sweaty, uncomfortable drive. Don’t ask.

In the realm of engines, heat is both a byproduct and a hindrance to making horsepower. Turbochargers compress intake air in order to better fill an engine, simultaneously heating the air as well. Exhaust ports, firing on pure hellfire, also generate significant underhood heat, captured within exhaust pipes and manifolds.

All of this latent heat seeks to raise the temperature of intake air, which needs to remain as cool as possible to generate power. The captured engine heat also has a tendency to spread its effects, melting nearby wires, downpipe-adjacent body panels, and causing the firewall or foot panel area to become unbearably hot.

Enthusiasts often go to extreme measures to withstand the heat, especially during extended track or racing outings. Some users employ massively heavy intercoolers, ground-scraping cold air intakes that snake out of the engine bay, and double thick socks that keep burned toes at bay.

One of the solutions from Design Engineering, Inc. (DEI) is the Reflect-A-GOLD heat reflecting tape. Similar to the gold thermal tape used in aerospace and the racing industry, Reflect-A-GOLD is a self-adhesive golden tape that DEI claims can reflect up to 80% of radiant heat and can handle continuous operating temperatures of 850-degrees F, with the adhesive side rated up to 325-degrees F.

The Reflect-A-GOLD tape has many potential uses in the performance car market. By wrapping an air intake box or tube, the intake air can be shielded from heat. Firewalls or rear decks can also be covered in it, keeping engine bay heat from entering the cabin. The tape can even be applied to certain sheet metal heat shields, increasing their effectiveness.

As opposed to more expensive wraps, blankets, or sprays, the gold tape is easy to apply (peel and stick), very thin for clearance, and lightweight. We’ve always liked its simple nature and you’ve no doubt seen golden thermal tape applied to the firewalls and airboxes of numerous racecars. But how well does it work?

PARTS TESTING

Our testing idea is deceptively simple – torture blast the Reflect-A-GOLD tape and see how it holds up. Using the blue flame of our torch, rated at 3000-degrees F, we’ll be testing to see the effective temperature reduction and reflection of the Reflect-A-GOLD tape.

Unless your car is on fire and melting to the ground (at which you’d have bigger things to worry about – Ed.), it’s unlikely to see any temperatures near 3000-degrees F. But using this high of a temperature, far beyond the rated capacity of the tape, will allow us to display the behavior of the product under incredible stress.

In order to keep our results consistent, all of our testing was done with the same ambient air temperature and sensor. Our sensor was tied into place on a vice and the distance to the torch kept constant between our two tests.



RESULTS

Our first test consisted of the 3000-degree torch flame being applied directly to a steel plate, which itself was in direct contact with the temperature sensor. Our initial temperature reading was at 83-degrees F. After a 20-second burn cycle, our sensor was reading a temperature of 205-degrees F.

For the next test, the same steel plate was covered in Reflect-A-GOLD tape on one side. After waiting for the temperature sensor to normalize back to 83-degrees F, we completed another 20-second burn cycle at the same distance. Our new ending temperature was now 95-degrees F. That’s a 54% reduction in heat.

Pushed almost ten times past its rated fire resistant heat capacity, the Reflect-A-GOLD tape charred and burned on its outer layer, as expected.

Still, the tape managed to pull off a 110-degree reduction in temperature and resisted the fire with its inner secondary layer. These are impressive results, especially for a roll that is as easy to put on as masking tape.

The Reflect-A-GOLD tape isn’t what we would consider super cheap, a 1’x1’ piece runs around $20 but it’s perfect for thermal situations that require low clearance, odd shaping, or just a small shield (around a exhaust pipe, for instance). As a tip, the Reflect-A-GOLD tape rolls, 2”x15’ for around $40, are much better bargains for covering intake tubes and airboxes.

Contact
Design Engineering Inc
www.designengineering.com

Carbon fiber is one of the most popular high-end composites currently used in the automotive industry. Racing series such as Formula One and the American Le Mans Series make generous use of the material for body and chassis construction. Street users, mesmerized by the weave of carbon, have made carbon fiber popular in the construction of wings, interior trim/paneling and lower grade body panels such as hoods and trunks.

Carbon fiber has a very good strength-to-weight ratio, making it an ideal replacement for metal in situations where weight is more important than cost. Versus steel, carbon fiber has more than 2.5-times the tensile strength and, due to a lower density, a much lower weight. Pure carbon fiber also has low thermal expansion, with electrical conductivity dependant on the type of material used.

But the name carbon fiber itself is a bit of a misnomer for the street-based end user because most parts readily available for sale seem to contain more fiberglass than actual carbon fiber in their construction. These cheap, often knock-off “carbon” hoods, shift knobs and trunks can be found at the local swap meet and aren’t worth much more than their weight in rocks. There are many different methods of manufacturing carbon fiber products, of which some methods can be carried out at home.

For the garage carbon fiber manufacturer, the easiest method is referred to as “wet” lay-up. A mold is manufactured of the end part’s shape (well, sometimes, some amateur users just eyeball it with varied results) and then raw carbon fiber fabric is laid on to the mold.

A fiberglass resin is then applied on top of the carbon and the part is either left to air dry in the open or put into a bag, from which all the air is vacuumed out. Vacuuming the air out seeks to more evenly distribute the resin across the surface of the part as well as remove air bubbles for strength.

The method used by most professional racing teams and high quality parts manufacturers is “dry” pre-peg carbon fiber, with the use of an autoclave. Molds are still required to produce parts in this instance, although pro teams will be more specific about the materials used for their molds. Due to the heat of an autoclave, fiberglass molds will deform and are unable to be used as many times as a metal mold.

Carbon fiber that is pre-impregnated (i.e. pre-preg) with epoxy resin is laid into the mold and then covered with releasing films and agents. The entire piece is then bagged and vacuumed clean of air. From there the piece is inserted into an autoclave, which is, basically, a large oven. The parts are heated to cure the carbon fiber and then the part is finished. Dry carbon parts can be produced with a much lower weight than wet lay-up parts since there is much less resin used (hence the “dry” name) and with a higher strength.

Formula One chassis and many common racecars parts, such as World Challenge front splitters, are made of sandwiched carbon fiber. These parts use carbon fiber sandwiched around aluminum honeycomb or foam core, increasing the strength of the part tremendously.

When you need a front splitter that can survive a curbing hop at 120mph, you need the good stuff. For now, we’re just going to cover the dry production method for non-sandwiched carbon parts.

We paid a visit to K&N Engineering’s carbon fiber department, where they produce, in-house, all the carbon used in their air filter and intake products.

Because of the temperature change throughout the day, K&N starts work at 4AM and ends by mid-morning time. This helps the composites team avoid the rise in temperature from the sun. K&N manufacturers all of their carbon fiber products in the dry pre-preg method using resin-impregnated carbon fiber sheets. From there, the carbon sheet is laid into the part mold by hand. At K&N, CNC-machined molds are made for every different mass-produced carbon product. This ensures consistency and less disposal than fiberglass molds, which deform after a few uses.

A special release film is placed over the carbon fiber and mold package and then the whole piece is bagged and placed into the vacuum bag. Using special vacuum hoses, all the remaining air is sucked out of the sealed bag.

The parts are then placed into K&N’s autoclave. Multiple molds and parts can placed into the autoclave at one time. Once out of the autoclave, the carbon parts are taken out of the molds and then trimmed. The finished carbon fiber piece is then ready for packaging and sale.

Sources

APR Performance
909-594-3796
www.aprperformance.com

K&N Engineering
www.knfilters.com

Features:
·    Reinforced shoulder tread blocks
·    Continuous center rib design
·    Specially formulated tread compound
·    Reinforced internal construction

To the average commuter, the rubber doughnuts underneath their car are only good for one thing – to keep their wheels from getting scratched. Most “normal” people don’t pay close attention to what keeps them on the road. They’ll buy re-manufactured tires (four for $100 on special! – Ed.) and rarely ever check the pressures. So why then has every tire manufacturer on Earth released a new all-out performance street tire in the last couple years? For you, of course.

Compare a normal driver to the average OR reader, who obsesses about the perfect hot tire pressure and tread design. Commuters don’t understand the capabilities and intricacies of a performance tire the way that a gear head would but they’re not the target buyer. The OR reader is the one with the modified car, bursting at the seams, asking for every nuance of grip that it can muster.

The OR reader is the one that will win time attack championships, club races and autocross national titles. These are the things that can help boost a brand’s reputation, reaching down to even the commuter level. When it comes to competition, everybody’s out to win.

The NT05 is Nitto’s latest maximum performance offering. With a low UTQG rating of 200, it’s matched up against the usual SCCA Street Touring standouts like the Falken RT-615, Yokohama Advan Neova, Toyo R1R, Hankook RS-3 and Dunlop Direzza Sport Z1. UTQG wear ratings are arbitrarily determined by each tire manufacturer so they are not true yardsticks with which to measure how soft or sticky a competitor tire really is.

The first striking thing you’ll notice about the NT05’s design is the tread compound. The outer edges feature huge blocks of rubber with a few sipes for water evacuation. The center features what Nitto calls a “continuous center rib design”. This equates to a thick strip of rubber right through the middle and two large channels on each side. These channels will help with wet weather grip, although the NT05 is not recommended for snow use.

Surely taking a few cues from their NT01 r-compound racing tire, Nitto has created a very fast street tire that is capable on track as well. We sampled the 255/40/17 NT05 size at Spring Mountain Motorsports Park in Pahrump, NV during the Redline Time Attack weekend. The test car was our full weight, registered and daily driven Project Evo IX. The NT05s were not heat cycled or shaved before they hit the track.

Right off the bat, the NT05s displayed their high level of grip. Entering into the medium-speed Turn One off of the front straight,Project Evo IX averaged a lateral load of 1.01g and a peak spike of 1.61g. Through Segment 4, a tight hairpin left, the NT05s scored a peak lateral load of 1.22g. Perhaps most telling though is the high 66-68mph average speed maintained through Segments 7 and 8, which are undulating mixtures of hills and turns.

The NT05s also displayed good heat resistance, with no chunking or tearing appearing at all after they had gone on track. The tires also showed very little graining or overheating across the surface, its lack of tread squirm no doubt helped by its large tread blocks and relatively shallow molding depth.

The key thing to remember is that Nitto had the intention of creating a tire that was to be used on the street first and the track second. They were not in the market to create an all-out performance street tire like the Yokohama Advan Neova AD08, instead focusing on a balance of wear life, grip, price and noise. The NT05 doesn’t quite have the steering precision of the Neova tire but it’s still one of the fastest street tires on the market today and comes in at a much lower price than Yokohama as well.

If you’re looking for a decently priced street tire for your project car, you can’t lose with the NT05. You’ll have more dry grip than you can legally use on the street and hitting the track on the weekend won’t require a tire swap. That’s what we’re always looking for in a performance street tire.

Source
Nitto Tire
www.nittotire.com

In our past Tire Tech – How To Read A Tire Sidewall article we covered UTQG ratings, tire sizing and load/speed ratings. Those are the basic requirements for understanding what kind of tire you’re holding in your hands. But, before you head out and laugh in the face of the tire shop help, there’s more. Much less publicized is the manufacturing date stamped on to the sidewall of every tire.

Imagine this scenario – with all sorts of numbers and letters bouncing around in your head, you head out to buy some new tires for your rubber roaster. You know what size, brand and, thanks to us (no applause necessary, really – Ed.), model you want. It’s got the right stickiness, low treadwear rating and high speed/load index. Now it just comes down to price.

Going Out Of Business Tire Shop (GOOB) has the tire for $100/each. Everything Must Go Tire Shop (EMG) has the tire for $90/each. Since they’re the same spec, you’d just get whatever was cheapest, right? You shouldn’t.

What if we told you that EMG’s tire was actually three years older than GOOB’s? Doesn’t sound like such a good deal any more, huh? That $10 savings means using a tire that has sat on a rack gathering dust and hardening. It’s even worse if they’re r-compound racing tires. We’ve seen pro racing teams lose more than a second per lap from using race tires that are a little over a year old. When it comes to going fast, fresh rubber counts.

The way to check that you’re getting the freshest tires is to check the manufacturing date. Many tires shops won’t mention this to you. Hell, some don’t even know themselves. It’s actually quite simple. Printed on the sidewall of almost every tire is a four-digit code inside an ellipse. The first two digits are the production week of the tire; the second two digits are the production year of the tire.

Example: Kumho V710 racing slick tire

Manufacture code: 3705 = September 2005

37th (week) = September

05 (year) = 2005

In our example, we use a Kumho V710 racing tire with a code of 3705. This means that the tire was made in the 37th week (September) of 2005. Similarly, a code of 0310 would mean that the tire was made in the 3rd week (January) of 2010. With 52 weeks in a year, figuring out the tire’s manufacture date is easy.

And yes, our Kumho is a very old tire by today’s standards. If you remember correctly, we blew one of these up at the track on Project Evo IX.

Next time you go buy a set of tires, arm yourself with OR knowledge. Ask for the tire manufacture date and aim to buy performance tires that are at least less than half a year old. If the shop doesn’t know the manufacture date or how to check, take a look for yourself. Wait for a different shipment if it comes down to it and you have the time. And, if your shop doesn’t move enough of the tire you want and can’t get anything new enough, maybe try buying elsewhere.

Tires are simple to understand, right? They’re all black, round and made of rubber. As long as they fit around the wheel, they should be good. Not really. As an OR reader, you wouldn’t go into the local Pep Boys and sling four of the best Chinese remanufactured specials (on sale for $80! – Ed.) on to your car. You want the best for your dollars and learning how to read a tire is the first step.

Printed on the face of every tire’s side, called the sidewall, is a series of numbers and letters. With these, you can figure out the tire’s general traction capabilities, age and size. Combine these specs with the price you’re willing to pay and you should be able to figure out the right tire for you.

Tire Size

The most important thing to pay attention to is tire size, printed in a format that will read something like “225/45R17”. Some tires will also begin with a letter, such as “P225/45R17”, where the “P” means that the tire is meant for passenger vehicles. Other letters include “LT” (light truck) and “T” (temporary spare).

The first number is the width of the tire’s face from sidewall to sidewall, measured in mm. The above example is 225mm across the face. The second number is the aspect ratio, also commonly referred to as the profile. This number is the height of the sidewall and is read as a percentage of the tire width. In our example, the sidewall height is 45% of 225mm, 101.25mm. The letter “R” means that the tire is a radial tire, the most common currently in production. It’s unlikely that you’ll run into any other letter in that spot. The third number is the wheel diameter.

Tire sizing is important because it directly affects tire fitment (i.e. rubbing), gearing and your speedometer. Your car’s speedometer is calibrated to the factory tire size and the tire’s circumference, i.e. distance around its face. Since tires are your car’s only connection to the ground, tire circumference is used as a function of rotation per time to figure out vehicle speed.

By using too large or too small of a tire, your speedometer will think you’re going a different speed than you really are. You can also use this to your advantage during autocross runs or at the track by using a thinner tire for a smaller overall diameter, shortening the gear ratio.

UTQG

UTQG, which stands for Uniform Tire Quality Grades, is a general system for judging overall tire characteristics. The ratings are broken down into three parts: treadwear, traction and temperature.

Treadwear

The UTQG treadwear rating ranks overall wear rate and softness. In general, the lower the number the higher the dry grip of the tire. Commonly found passenger car tires rank in the low 300s, ultra high-performance street tires in the low 200s to mid/high 100s and racing tires are usually 100 and below.

Traction

UTQG traction rates a tire’s braking grip over a wet surface under a controlled National Highway Traffic Safety Administration (NHTSA) test. Grades given are AA, A, B and C, with AA being the highest. This grade is only partially relevant for OR readers since the NHTSA doesn’t test for dry grip or cornering on a wet skidpad.

Temperature

UTQG temperature grades include A, B and C, with A being the highest. Grades are tested and given out by running a tire against a roller in a controlled test. This test is important because high-speed operation causes heat to build up in a tire. A higher temperature resistance will survive high-speed operation for longer periods of time.

Load/Speed

A tire’s load and speed rating is usually given in a format similar to “95V” and will follow the tire size, read completely as something similar to “225/45R17 95V”. The numbers are the tire’s load rating and matches to a general ability to carry weight. The letter is the speed rating and different letters (below) are used to designate a tire’s maximum speed rating.

Seemingly one of the most successful, cash-infused tire companies at the moment, Continental Tire went balls to the wall for the launch event of the Extreme Contact DW (Dry Wet) and DWS (Dry Wet Snow) tires. California Speedway, now Auto Club Speedway, played host to the event with the oval, infield, go-kart track and parking lot rented out for testing. On hand in the parking lot were a wet skidpad, wet braking test and two tight autocross courses (dry and wet).

Continental Tire’s test fleet of BMWs and Mustang GTs were on hand for journalist abuse and we delivered. The BMW 3-Series proved to be an easy low-speed drift machine on the wet autocross course, while the Mustang GT left us pining for a competent limited-slip differential (LSD) to be installed in the rear axle.

Muscling the Ford pony car around the wet skidpad became an exercise in understeer and throttle management as the V8’s torque refused to properly overcome both of the rear Continental DWS tires with power-on oversteer. Luckily, the DWS tires provided enough traction and wet surface feel that balancing the Mustang around the wet asphalt was no problem.

Still, the star of the day was the Extreme Contact DW tire. We’ve driven on Continental’s previous ContiSportContact 3 performance offering and found it to be very consistent and with a pretty good level of grip. The DW was our main focus for the day and it did quite well for an all-season tire (all season in CA at least, we only get dry and some wet – Ed.).

The DW doesn’t provide the outright dry grip of uber-top tier rubber, like Yokohama’s Advan AD08 Neova tire, but, then again, Neova’s cost an arm and a leg and will wear out faster than you can say burnout. For the average real world driver, the Continental ExtremeContact DW provides a better balance between cost and performance and will provide more than enough grip for the street and, occasionally, the track.

We pushed the DW on the autocross course, on CA Speedway’s massive oval (in an ex-Toyota Pro/Celebrity Celica racecar) and in a timed “time attack” session on the infield course. Even tith the launch event full of club racers and karting enthusiasts, we took the 3rd place trophy. The DW tire proved to be very responsive and had an easy to find limit of grip, making learning both easier and faster.

While out on course, the DWs delivered. They were very consistent over the driving period and delivered more grip than we had originally anticipated. The current generation of street tires have progressed with amazing leaps and bounds, almost matching racing tires for consistency and grip.

The Continental DW and DWS tires are quiet, comfortable, consistent and have a decent amount of grip. These weren’t designed as one-shot wonder Street Touring autocross tires but If you’re looking for a grippy tire that you can slap on to your street car all year round, the Continental DW and DWS are very good choices.

Update (Nov. 2009):

Our very own Mitsubishi Lancer Evolution track car test bed, Project Evo IX, recieved an invite to the annual Evo vs. STI Shootout. The time trial competition is run on a spec tire, the Continental ExtremeContact DW tire, meaning all competitors would be on the same exact tire. This evened out the playing field, making for closer competition.

After a day on track, Project Evo IX emerged as the fastest car of the day, beating full racecars. Equipped with an aftermarket KW suspension, 400hp and 265/35/18 Continental ExtremeContact DW tires, we set a laptime on track faster than both the Porsche 911 Turbo and the Chevy Corvette Z06. Our car is registered, driven regularly and is full weight.

Source

Continental Tire

www.continentaltire.com

If you’re anything like us, your hands sweat like fat sausages when you drive fast. On track, our palms get so sweaty that the steering wheel and shift knob can become slippery. Being too slow to catch a tank-slapper or missing a shift because of grip, well, sucks.

That was our first reason for banning the use of smooth metal shift knobs. Driver comfort while on track is very important to being able to focus and drive fast and that’s one of the biggest reasons to wear driving gloves during a track day.

Racers all wear the latest safety gear – neck restraint, suit, gloves, shoes – because they bang doors and run the risk of serious damage during competition. Since HPDEs, driver’s schools and track days are not run wheel-to-wheel, there isn’t so much a risk of balling up your car and catching on fire.

Although driving gloves aren’t required during casual events, we always prefer to wear a pair to maintain proper grip throughout the entire session. It’s a safety bonus that, by wearing fireproof gloves instead of leather gloves, your hands will be able to open any number of hot surfaces should your car catch on fire.

5Zigen’s ARD racing gear division recently released their ARD-272 driving glove, a FIA-approved glove that appeals to both racers and weekend drivers. In compliance with FIA standard 8856-2000, the ARD-272 glove comes in four different colors and four different sizes.

The ARD-272 glove is externally stitched to prevent irritation or itchiness to the hand inside. Every pair of gloves does come with a distinctive, almost tribal, logo pattern on the outside of the hand and a textured surface covering the palm and finger wear areas.

The secondary textured layer is almost like treated leather in terms of feel but is soft and pliable. FIA standards regulate that gloves only use leather or leather-like materials across the tactile surfaces of the hand, since leather shrinks when exposed to fire. By only putting the textured layer across the wear areas, ARD was able to combine the ARD-272 glove’s elastic flexibility with the outside layer’s grip and strength.

The resulting combination provides a glove that fits easily and tightly, the material will stretch slightly across your hand, and isn’t stiff at all during hand movement. Although it feels slightly thinner, we’d say that this glove provides greater tactile feedback and movement than the Sparco Profi gloves that we also have.

FIA standard 8856-2000 mandates that during testing a glove’s finger seams be exposed to flame for 15-seconds. Four different gloves of the same type, in total, will be tested under fire and the threads should not “melt, show after-flaming or break”. The FIA also requires that no flaming or molten debris be present and that the gloves don’t split under the stress. Fully compliant with the FIA standard, the ARD-272 gloves should be good to allow for a speedy escape from a car on fire.

One plus of the external textured layer is its ability to be used with non-suede steering wheels, i.e. leather wheels and most stock steering wheels. Suede-palmed racing gloves provide excellent grip when combined with suede wheels but often don’t grip as well on leather or vinyl surfaces. If you’re using your car for autocross or track use and haven’t switched out to a suede wheel, the ARD-272 gloves will be right up your alley.

The ARD-272’s external leather-like layer provides just the right amount of friction to maximize handgrip across other leather and vinyl-type surfaces. In simpler terms, the ARD-272 gloves work great with stock and leather aftermarket steering wheels and will provide better grip than a comparable suede glove. We realize that these gloves aren’t the cheapest on the market but their combination of safety, grip, looks and flexibility will surely appeal to many enthusiast drivers. Just be sure to air out the sweat from the insides to avoid any unnecessary glove funk.

Item #ARD272
MSRP: $200 ($179.95 below at 5Zigen store)
Sizes: S, M, L, XL
Colors: Blue, Black, Gray, Red

Sources
5Zigen USA
www.5zigenusa.com
www.5zigenusastore.com/arragl.html

Size tested: 285/30/18
Type: Ultra-high performance tire
UTQG: 180 AA A
Test car: Project Evo IX
Test track: Willow Springs

Features:
· Serrated groove walls
· Heat releasing dimples
· Optimum groove position
· Rounded tread block design
· Unique casing shape
· Micro silica compound

The Yokohama PR catalog can talk all day about silica construction, block casings, and environmental designs but, when it comes to performance, tires speak for themselves. As anyone in the street tire autocross scene can tell you, the Yokohama Advan Neova tire is the best street tire on the market today.

With its high price tag and limited availability, the Neova tire scares away many potential buyers. But those owners of high performance or competition cars would be missing out if they let their wallets make their decisions. Yokohama is one of the most well known Japanese tire manufacturers, with offerings in club racing and the ALMS, and the Neova is their best.

First off, the Neova tires is difficult to track down. Not a high volume seller, the tire is, in fact, often out of stock at Yokohama Tire HQ itself. Trying to find a last minute 18-inch Neova at your local Discount Tire is going to be next to impossible. Your best bet is to shop at racing or performance shops and still factor in a wait time.

The Advan Neova is Yokohama’s current flagship tire and sports all the features that they could pack into a street tire. We tested the Neova tire on Project Evo 9, on both the street and the track. Our first impressions of the Neova tire came on the 2-hour drive from our headquarters to Willow Springs Raceway.

The Yokohama Advan Neova sports all the comforts of a true street car tire. There is more road noise transferred into the cabin than from an all-season touring tire, but very little when compared to a racing tire or event some other high-performance street tires, such as the Toyo R1R.

The Advan Neova did however provide outstanding stability, grip, and steering feedback. Through freeway sweepers, lane changes, and off-ramps, the Neova gave more driving feedback than any other tire we’ve driven on.

The Advan Neova is even above average in the wet, as we found later during a rainy stretch. Some ultra-high performance tires get their dry grip by sacrificing wet weather stability and capability but the Neova managed to retain its feedback and feel.

We also took the opportunity to test the Advan Neova tire at Willow Springs Raceway, the “fastest track in the west”. With Willow’s daunting Turn 8 and 9 complex capable of propelling Project Evo 9 over 120mph through turns, many street tires have given up the ghost during testing.

Once on track, Project Evo 9 began to push the limits of the sticker-fresh, full tread depth Yokohama tires. We didn’t do any heat cycling, shaving, or preparation. Especially in the summer, Willow Springs’ high speed and high load turns have a tendency to punish front tires.

Putting Project Evo 9 on the track in 15-minute sessions, we switched on our datalogger and flipped open our notebook. Our test driver returned with similar feedback to our street drive. The Yokohama Advan Neova tire displayed high grip and sharp steering feedback on track, especially through the very quick Turn 2 (average 87 mph) and Turn 8 (average 119 mph) areas. With consistently high grip marks (at or above 1 lateral-g in almost all corners), the Neova tire could in fact match the pace of racing tires from just a few years ago.

Like any street tire, the Neova didn’t display as much heat capacity as a true racing tire, although it was consistent throughout the entire session, not completely dropping off into complete slipperiness like other street tires after a few laps. We found our lap spread to be within 1-second throughout the session.

Our final impression of the Yokohama Advan Neova is one of surprise. It’s not very often that we run across a tire that combines the wet weather capability and noise of a street tire with the grip and feedback of a racing tire. We had heard good things about this tire but its performance truly is excellent. The Neova’s only downside is its pricetag, almost $320/tire in this size, which matches or exceeds racing tire prices.

But, remember, your tires’ contact patch is the only thing holding you to the ground. If you have a high-performance car, such as a Porsche, BMW, Corvette, or Viper, that demands the best in grip and performance, you’ve found it.

Size tested: 255/35/18
Type: Extreme performance tire
UTQG: 140 AA A
Test car: Project Evo IX
Test track: Willow Springs (Redline Time Attack)

Features:
· Silica-reinforced, high-grip tread compound
· Unidirectional “arrowhead” tread design
· Tapered center block edge
· Multi-width EVAC channels
· Stability control slits
· Modified radial construction casing

Before we get too far into this review, let’s just lay it out there – the Toyo R1R tire is not for everybody. It’s not a tire for getting groceries, driving to Granny’s or zoning out in stop-and-go traffic. Toyo sells other tires for those purposes that are both quieter and longer lasting.

The R1R is an r-compound racing tire disguised as a DOT street tire. But if you’re interested in putting every last bit of power down to the ground or autocross in the SCCA’s Street Touring class, then please read on.

Why should the R1R be used by only the most hardcore enthusiasts and drivers? Compromise, really. Every single thing that you change or modify on your car will compromise it in some way. Your car can become stiffer, louder or lighter with a few changes. But luxury and comfort often get thrown out the window.

The Toyo R1R is designed first and foremost as a performance tire. It comes packing many design cues that can also be found in the Toyo R888 r-compound racing tire. Design cues that may bother your average Corolla S commuter.

The R1R’s sidewalls are stiff to give a crisp turn-in response and have a reinforced casing to avoid deflection under hard cornering. Driving on the R1R is not uncomfortable by any means but the stiffness does make the R1R ride hard when compared to your standard off-the-shelf all-season touring tire. The “arrowhead” tread design is supposed to aid with wet traction, which is good since the R1R has such huge tread blocks for dry grip, but it also increases the road noise transmitted into the cabin.

Wear and longevity are also an issue. With a soft, grippy compound and a low 140 UTQG wear rating, the Toyo R1R will not last as long as a El Cheapo touring tire. But, then again, the R1R will demolish any all-season or touring tire in terms of outright grip. In its comfort zone, at the track or in performance driving, the R1R shines.

We tested the 255/35/18 Toyo R1R on Project Evo IX during the Redline Time Attack Willow Springs event (full tread depth, no break-in or heat cycling). With a 255-width and a 140 UTQG treadwear rating, the R1R is at the extent of the limits and is one of the tires to have for the Street Class. The UTQG rating also bumps it up against the rules ceiling in the SCCA’s Street Touring (STX, STU, STR, etc) class.

The R1R was clearly designed to dominate in these street-based performance environments. Once on track, we knew the R1R was not your average street tire. At a hot track in the blazing heat of a Southern California summer, the tire did drop off quite quickly but during the first couple initial hot laps, the grip was commendable. We nailed our fastest lap (good for 3rd in Street AWD) on our second hot lap and spiked 1.32 lateral-g in Willow’s on-camber high-speed Turn 9.

We did wish that the R1R had a more responsive turn-in and steering response, the proper slip angle for the tire is difficult to find at times, but the high grip level is hard to beat. The tire also exhibited zero chunking or tearing (always the bane of a street tire driven on track) during our track testing. Ken Motonoshi, SCCA autocross national champion, also advised us that the tire would get faster as it wore down.

We’re hoping that as the tire begins to wear away and the tread blocks get shorter, there will be less tread squirm and the turn-in response will pick up. If the tire gets even faster, fantastic. Although, it’s hard to believe just how fast this street tire really is already.

Source
Toyo Tires
West Coast: 800-442-8696 (6:30am to 5:00pm Pacific Time)
East Coast: 888-444-8696 (9:30am to 8:00pm Eastern Time)
www.toyotires.com

The stiffer a chassis is, the less it will flex when forces are applied to it, i.e. through the suspension. This means that forces from the road surface will be contained and absorbed by the suspension rather than being allowed to beat up the body shell. As the chassis is stiffened, ride quality will improve and stiffer springs can be used before the chassis throws a fit. Hell, even OEMs use the methods outlined here on such cars as the Acura TL and the Mazda RX-8 R3.

Our thought process behind this urethane foam method is – when it comes to making your car stiffer and stronger, sometimes you just don’t want a full roll cage. Tying together the chassis with a custom welded cage would increase chassis stiffness by a large amount but if your car sees more street time than track time, cracking your skull open on a metal tube doesn’t exactly sound like a great Friday night.

This leaves you with the options of stitch welding, bolt-on chassis bracing bars, a simple four-point roll bar or urethane foam. Bolt-on braces and bars often have little effect or gain on chassis stiffness and they often cost a pretty penny. Doing something for dirt-cheap in your own garage sounds pretty tempting, huh?

Keep in mind though that the foam you want to put into your car isn’t the cheap spray insulation that you can buy at your local Home Depot. Many of those foams have a density in the range of 0.5 lb per cubic foot. We were after the 2 lb per cubic foot injectable kits for use in upper A/B/C pillars (made by Handi-Foam) and the 8 lb per cubic foot stuff for the rockers and frame rails.

Foams in the 8 lb per cubic foot density are commonly used in marine applications and we’ve never come across one that was an easy to use two part injectable kit. You’ll have to mix and pour these tougher foam types. Our expanding urethane foam pour kit was sourced from US Composites and came in two unassuming metal cans. The liquid in the two cans is mixed in a 1:1 ratio and has a claimed 45-second pour time. In actual use, the pour time (the time you have to pour it into your car before it bubbles over and turns into a solid) seems to be closer to half that.

We mixed up about 20-ounces at a time and a paint mixer/power drill combo came in handy as we zapped the mixture for 15-seconds before beginning the pour into our rocker panels. Any longer and the foam would begin to harden in the funnel as we poured, clogging any more of the mixture from entering our tester Nissan chassis. If you want to avoid ruining and wasting any foam, funnels or supplies, you’ll have to be quick with your hands.

The pourable urethane foam expands to eight times its liquid volume, meaning the 16 lb net weight size kit is more than enough to handle most any car’s rocker panels/side rails. Buy more than one kit if you intend to fill up a subframe or tubular control arm. Handling the foam itself isn’t difficult at all but proper prep is a must. The foam is pretty much impossible to clean off once hardened and hardens very quickly.

Before mixing and pouring began, we covered our 1989 240SX’s interior completely with a plastic drop cloth, placed newspapers underneath the car (foam will drip out of the rails on to the floor), wore disposable work clothes (no tuxedos here) and pre-cut bits of duct tape were placed next to every orifice that we pouring into. This was so that the holes could be covered after pouring and the expanding foam could be captured inside, instead of bubbling out. We also made sure to tape up the backside of the lower seat belt holes in the rockers, so that the foam didn’t fill up the threads for the mounting bolts.

The injectable 2 lb per cubic foot foam was by far much easier to use. A kid could literally figure out how to use the kit. Not recommended though as any kid on Earth would probably try to eat some of this stuff. Nasty. The Handi-Foam kit comes pre-assembled with two cans in an injector setup. You pop open the two cans, release the nozzle and you’re ready to go. Stick the injector tip into you’re A/B/C pillar holes and let the stuff loose. Be sure to use the duct tape trick again to seal the foam inside as it hardens.

Although we don’t have any exact chassis stiffness increase percentages, a simple garage measurement yielded a stiffer chassis with a 1/4-inch front and 1/8-inch rear increase in frame to ground height as the car was jacked up at the front left, with a floor jack saddle height of 10.75-inches. Road testing the car also provided a noticeable difference, with less creaks going up driveways and a noticeably smoother ride over broken pavement. For one afternoon’s work in the garage, and less than $80, why wouldn’t you try it?

Source
US Composites
www.uscomposites.com

Handi-Foam
www.fomo.com

Beyond possible suspension travel and alignment issues, some of the biggest concerns when it comes to lowering a car should be the effects on the roll center and on bumpsteer. Looking at a car head on, the roll center is quite literally the point around which the vehicle rolls when cornering.

It’s determined by drawing a straight line from the instant center to the middle of the opposite tire’s contact patch. Do that for both sides and the point at which the lines intersect is your roll center point. For front strut cars, like the E36 M3, WRX and Evo, the front instant center point is the intersection of a line parallel to the strut top and a line intersecting the lower control arm.

The problem with lowering your car excessively is that the roll center is always lower than the center of gravity and will actually fall more than the center of gravity with a decrease in ride height. As your front roll center approaches the ground, your car will actually begin to roll over more because of the increased torque leverage from the larger roll couple. This is bad for steering response, handling and basically ruins the entire point of buying a lower, stiffer suspension. This also means that you’ll need overly stiff swaybars or springs in order to compensate.

Excessive lowering also amplifies bumpsteer, which is where your toe settings will actually change based on suspension travel. Imagine you’re flying through a sweeper, cornering steady state, you come up on a slight undulation in the road and bam, your car darts even though you didn’t turn the wheel and you didn’t bottom out.

Thanks to excessive bumpsteer, your wheels just self-adjusted their toe setting. It’s caused by the increased difference in arc travel between the lower control arm and outer tie-rod end, and it only gets worse after changing ride height. It’s bad too, for obvious predictability and control reasons.

Curing roll center and bumpsteer problems has generally been a race-only proposal, but drop-in products do exist for garage mechanics to get their fix. Ideally, the best way to perfectly cure roll center problems is to create new control arms, alter the control arm mounting points or raise the front subframe.

Conversely, bumpsteer should be adjusted by using heim-jointed tie-rod ends and specially measured stacks of spacers to drop the connection of the steering arm to the spindle. These solutions, however, require careful race shop measurements and custom fabricated parts.

Size tested: 235/45/17
Type: Ultra-high performance tire
UTQG: 240 AA A
Test car: Project Evo IX

Features:
·    Lower sidewalls reinforced with DuPont Kevlar material
·    Jointless Band Technology to help maintain shape and performance at highway speeds
·    Max Flange Shield to protect rims from curb damage
·    Asymmetric design for easy mounting and tire rotation
·    Motorsport-inspired tread compound that promises dry and wet grip
·    Multi-Radius-Tread Technology that promises to distribute contact patch pressure smoothly during cornering
·    Unique bead fit system helps with tire and wheel mounting pressure

At the moment, it seems most tire companies just want to go to war in the performance street tire market. With outright handling records and SCCA Street Touring autocross national championships on the line, numerous tires have been released with 180 or lower UTQG ratings.

These premiere street offerings provide race tire-level grip but they also come with race-level pricing and incredibly quick tire wear. Not everybody can afford a new set of tires every six months. Luckily, Dunlop has released an ultra-high performance tire for real world street enthusiasts, the SP Sport Maxx TT.

As a summer tire, the SP Sport Maxx TT isn’t designed to be driven through snow or ice. It is, however, designed to provide optimal dry and wet weather grip. Think of it as a year-round Southern California tire (sorry Alaska). Dunlop’s recipe for the tire begins with the construction, which uses Kevlar reinforcement and Polyamide cord reinforced twin steel belts.

The tire tread itself is an asymmetric design that blends large tread blocks, for dry grip, with multiple water evacuation channels, for wet conditions. The SP Sport Maxx TT also features a curb protecting design that bulges slightly to protect wheels from scraping against curbs when parking.

“The SP Sport Maxx TT helps deliver great road feel, which is important for those who really love to drive.  The timely feedback from these tires allows the driver to react to turns and contours in the road,” said Razvan Bosomoiu, Dunlop general manager. By the time you read this, the SP Sport Maxx TT will be available in thirty-five sizes, ranging from 16-22-inch diameters.

On the streets of the real world, the SP Sport Maxx TT is a perfect fit. We tested these tires in a stock size fitment of 235/45R17 (on stock wheels) on Project Lancer Evo IX, which is equipped with stiff springs and spherical upper suspension mounts. Even with hard metal suspension bearings, the tire transmitted very little road noise into the cabin and, with 45-series sidewalls, absorbed bumps and shocks with ease.

Vibration through the steering wheel and directional hunting across the road was almost non-existent as well, which is more than we can say for some edgier performance street tires. With a UTQG rating of 240, the Dunlop SP Sport Maxx TT should also provide plenty of tire life before wearing out.