Berk Technology's BMW 135i Time Attack Demonstrator
Text and photos by Jeff Naeyaert
When Berk Technology set out to build a time attack car, their intent was not to build some sort of exotic open class killer; it was more to build a rolling test bed for their exhaust products and something that their high performance street customers could relate to. Thus it was decided that their efforts would evolve around building a car to compete in Redline Time Attack's Rear Wheel Drive Street Class. Street Class is something that Berk's customer base could identify with and would be a more powerful marketing statement.
An Alpine White 2008 BMW 135i with a 6-speed manual transmission was selected as a base vehicle as a large amount of Berk customers are owners of this car. The One Series' compact size, relatively light weight and twin-turbo six cylinder engine lend itself well to simple modifications and are easy to build into a competitive car.
 |
The engine on the Berk 135i remains very stock with only simple bolt-ons. It delivers 379 whp and 402 lb/ft of torque over a wide powerband with all day reliability.
|
 |
| The Berk stainless exhaust trims an amazing 40 plus lbs off of the BMW's total weight as well as unlocks a bunch of power over the restrictive stock exhaust. Even the race version of the exhaust isn't that loud and lets the delicious sound of the 120 degree firing I-6 engine come through. |
The 135's engine remains relatively stock. The restrictive stock exhaust has been totally replaced with a Berk system. Berk thinwall stainless 3″ downpipes replace the heavy stock parts. The downpipes reduce backpressure to improve turbo spool and HP/TQ numbers. They feature a heat insulating internal ceramic coating normally found on piston crowns to keep exhaust velocity up and underhood temps in check. Berk midpipes and race series exhaust system are also used. The race version features two mufflers that are center mounted on the chassis. By keeping all of the weight low and in the center of the car the weight distribution is improved and the CG (center of gravity) of the car is lowered. The race system has no muffler behind the rear axle which again improves weight distribution and handling by eliminating the 30lb muffler that would otherwise be hanging out near the rear of the car.
 |
The AFE cold air intake system frees up a bunch of power over the restrictive stock intake that was designed to quiet the intake roar.
|
 |
The AR Design oil cooler is essential for any track driven turbo 1 series. 1 series BMWs run really high oil temps on the track and go into limp mode when the oil temp gets past a certain threshold. The AR design cooler uses quality AN fittings and hose.
|
 |
| The oil cooler lives in the driver's side bumper duct. It works in parallel with the OEM cooler on the other side. |
The restrictive factory airbox was replaced by an AFE cold air intake using twin cone type filters. A Code 3 intercooler with a Spearco bar and plate core replaced the stock intercooler. The Code 3 part is much more effective being twice the size of the stock intercooler. It has better cooling and less pressure drop across the core. Engine management is handled using a stock factory ECU tuned with GIAC software. Fuel, spark and boost maps have been recalibrated for more power. An AEM water/methanol injection system is used to suppress detonation and to keep combustion temperatures in check. The One is notorious for super high oil temperatures sending it into limp mode. On the Berk car, oil temperatures are kept in check with a big AR Design oil cooler. A stock radiator was found to be adequate even under strenuous racing conditions. The engine pumps out 379 RWHP and 402 lb/ft of torque with conservative tuning and boost levels.
 |
An AEM Water Methanol injection system is used to suppress any chances of detonation and to hold engine temps down. We have used the AEM system with a great deal of success on our own project cars and highly recommend it for any forced induction use to control detonation and temperature. The AEM nozzle is shown here, it is critical for the system's operation as it atomizes the fluid into a fine mist.
|
 |
| An HKS blow off valve and Evolution Racewerks charge pipe help protect from compressor surge on overrun. |
