Feature – Berk Technology BMW 135i

The Berk Technology BMW 135i - simple and street legal

BMWs have long been renowned as both luxurious and as drivers’ cars. The former is because they hail from the land of Bavarian delights, infused with leather, climate controls and solid materials. The latter is because BMW has stuck to its guns over the years, retaining rear-wheel drive across most of its line and using manual or semi-manual transmissions exclusively in its popular M models (the M SUVs don’t count – Ed.).

But simply denying the addition of a torque converter doesn’t inherently make a great car. BMWs have been blessed for years with superb driver control, feedback and handling. It comes as no surprise that the German manufacturer can be seen in road racing, rally racing (we daydream every time that we see an E30 M3 rally video), drag racing, drifting and even motorcycle racing. In the US time attack scene, it’s Berk Technology’s BMW 135i that is keeping the flame alive.

With most of the modifications hidden from view, there's not too much to see in the stealthy engine bay

Just a couple years ago, BMW announced the development and release of their new twin-turbocharged inline-six gasoline engine. In the US, the engine debuted in the BMW 335i and 135i models and pushed just a hair over 300hp in stock trim. With the turbo engine in place, both cars were nearly as capable as the M3 but at a lower price. The ability to simply raise the boost and up the power made the turbo setup even more tempting. Nearly identical in many mechanical respects, the 135i’s squat body gave it a couple hundred pound advantage over the larger 3-series car.

On track at Buttonwillow Raceway during the Super Lap Battle finals - photo by Duane Uyeda

Most of the factory interior remains, aside from the Sparco seats and gutted rear

In their third year of time attack racing, Berk Technology decided to tackle the turbo BMW platform, entering this BMW 135i. Having previously campaigned a turbocharged Toyota MR2 and a Honda S2000, Berk Technology was no stranger to the track. As a manufacturer of exhaust and intake parts, Berk was also no stranger to modifying a performance car. But the BMW 135i brought its own issues.

The car was fresh and new, a great platform with which to reach new buyers and market the company. But the BMW was also untested and unproven, requiring patience and R&D. The choice was made early on to keep the BMW build simple and relatable. The Berk 135i was soon built for and campaigned in the Redline Time Attack Street Class.

The factory twin-turbocharged Berk Technology BMW 135i remains one of the few BMWs in US time attack competition

Lightweight carbon fiber shows its face in the hood, trunk, splitter and rear wing

This BMW 135i remains street legal with the stereo, climate control and most of the interior still intact. The race exhaust and graphics scheme are a bit much for a daily driver but this car is used mostly for time attack competition, taken to and from events without a trailer. With the Dunlop Direzza Sport Z1 street tires mounted up, this BMW is fully capable of driving to the track, setting records and then heading home in comfort.

A semi-gutted backseat and trunk combine with a small Braille Auto racing battery to shed weight

Precious pounds have been shed with the removal of the rear trim and backseat, addition of a smaller battery and switch to Seibon carbon fiber on the hood and trunk. The APR Performance aero additions are also carbon fiber, covering the rear wing and front wind splitter.

With the addition of Berk downpipes and exhaust, AFE intake and Code3 intercooler, power output has jumped past the 300whp mark. A Quaife limited-slip differential has been added but the six-speed drivetrain otherwise remains stock. The fixed caliper BMW/Brembo brakes in the rear have been retained but the front has seen a swap to a six-piston Rotora big brake kit, complete with two-piece rotors.

The APR front wind splitter rests just below the VFiber front lip

The suspension system is (relatively) mildly modified, outfit with a set of KW Variant 3 coilovers. The KW V3 coilovers are based around double adjustable twin-tube dampers, which Berk Technology has fit with custom spring rates. Final fine-tuning of the 135i’s balance can be done with the H&R swaybars. Vorshlag camber plates are used up front to properly dial in the correct alignment settings.

A Rotora big brake kit is used up front, the rear remains factory BMW

Despite its limited modifications, the Berk Technology BMW 135i has scored multiple top five finishes in the Redline Time Attack series Street Rear-Wheel Drive Class against competitors with lighter and more powerful cars. The driver for the coming 2010 season is Mike Bonanni, a Porsche Club of America driving instructor and regular time attack competitor. Bonanni’s experience from here will help aid in the development of one of the few time attack BMWs in the US.