There is an in depth article on the Berk Technology 135i Time Attack machine that has been terrorizing the import racers. Since the season is almost over it was time to unveil all of the speed secrets that makes the car so competitive. The car was built using many parts from many of the vendors here on E90post/1addicts. Here are a few shots. Have a look at the article it's a very good read!
http://www.motoiq.com/magazine_artic...onstrator.aspx
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.
KW camber plates have bearings to reduce flex and are easily adjustable for camber.
The KW Competition dampers are independently adjustable for compression as well as rebound damping and have stainless bodies for smooth non-stick operation of the spring perches.
The rear KWs are still adjustable for ride height and corner weight even though they have an independent spring. Having a separate spring takes bind off of the rear shock and makes for a smoother ride and less tire shock. Suspension is critical for any track car and Berk uses KW Competition 2-way adjustable coilovers. The Competition 2 ways have independent adjustments of the compression and rebound damping and are calibrated a little more aggressively than KW's Clubsport or Variant III lines. Velocity Motorsports supplied the adjustable links to adjust rear camber and caster as well as spherical bearing equipped swaybar endlinks. OEM E92 M3 sway bars are used for increased stiffness along with M3 front lower control arms for more negative camber. Polyurethane bushings are used to reduce subframe to chassis compliance. 18X9.5" APEX ARC-8 wheels are used with Hankook's Street Class dominating RS-3 tires to grip the road tenaciously. The track width is adjusted with Macht Schnell spacers and long wheel studs. An OS Gikken super lock 1.5 way differential distributes power to the rear wheels through a shorter 3.46 gear ratio.
Velocity Motorsports make these adjustable links to adjust toe and camber. They have spherical bearings to eliminate squishy rubber.
Machined aluminum subframe bushings eliminate flex and increase the sensitivity to chassis adjustment.
M3 lower arms for the front suspension are longer and allow more negative camber to be adjusted into the suspension.
The choice of Rotora brakes over the excellent stock Brembo's is a head scratcher. Berk is in the process of switching to some uber trick Performance Friction brakes soon.
The brake system on any race car is important. The Berk car relies on Rotora six piston calipers and 355mm rotors for stopping. We cannot figure out why the team would remove the stock car's excellent Brembo six piston OEM calipers for what seems a downgrade but we will be helping them with a set of Performance Friction super brakes which you will see featured here in a few weeks! It should be no problem to match PFC's claim of .2 seconds a lap or your money back guarantee! The brakes are fitted with Carbotech brake pads using XP10 compound on the front and XP8 compound in the rear. Ti Speed brake pad shims are used to reduce heat transfer into the ATE Blue brake fluid. Agency Power braided steel brake lines are used.
The rear two piston stock BMW brakes are pretty good as is.
The front brakes have some serious ductwork going to them, needed for slowing the heavy car from high speeds.
Agency Power braided steel brake lines improve pedal feel.
The L-Con crafted roll cage has perfect craftmanship. Look at how the floor plates wrap around the frame rails.
The upper part of the hoop has sano corner reinforcements and flawless tig welding. A hand-formed aluminum panel replaces the heavy sunroof.
Sparco seats save lots of weight. Sparco harnesses protect the driver and occasional passenger. A quick release steering wheel makes entry and exit of the car easier.
Sparco steering wheel is quite ergonomic!
Berk's race team manager Bee makes sure the car looks as good as it runs before getting back out on track! Louie Contreras of L-Con fabrication built a basic roll cage from DOM tubing for the car. Since this was a street class car, the stock interior had to be retained. It is quite difficult to cleanly integrate an effective cage with a full interior but L-Con did an amazing job. The cage improves safety and greatly improves chassis stiffness and handling. The interior also includes lightweight Sparco seats on Macht Schnell seat rails and 6-point harnesses. Switching to the Sparco seats trimmed 70 lbs from the car's total weight, nearly making up for the weight of the roll cage! A NRG steering wheel quick release and Sparco steering wheel round out the interior mods.
The V-Fiber air dam and the APR splitter make a lot of needed front downforce.
The 135i has good underbody aerodynamics. The car is nearly a flat bottom. This helps the splitter and diffuser's effectiveness. You can see the cool Berk exhaust very well from this underbody shot. The exterior features a bunch of functional and tasteful mods. An APR GTC rear wing and rear diffuser provides downforce in the rear balanced by an APR front splitter. A V-Fiber front airdam and side skirts manage airflow around the car. A vented Seibon carbon hood sheds weight and helps the engine stay cool. A Seibon rear deck lid also trims weight from the car. APR carbon GT3 mirrors cut drag as a large percentage of a modern car's drag is actually caused by the mirrors.
The Seibon carbon hood has generous venting. This greatly helps engine cooling and helps improve the effectiveness of the splitter.
The APR rear wing provides tuneable downforce. After a 2009 development season and with a new veteran driver Mike Bonanni, the Berk 135i entered the 2010 Redline Time Attack season with a roar securing enough points to just about clinch the 2010 season championship at this time. Below is the cars record in the 2010 season to date.
Buttonwillow – 1st Place – 1:58.839 **New Street Tire RWD Record
Las Vegas Motor Speedway – 2nd Place – 1:49.111
Auto Club Speedway – 2nd Place – 1:51.373
Willow Springs – 3rd Place – 1:30.415
The V-Fiber side skirts look good and somewhat help underbody aero by resisting the air's tendency to curl under the car.
The Seibon rear trunk decklid saves weight while the APR rear diffuser helps create downforce. ..and the Laura in the background does her best to distract photographers.
Despite its ontrack prowess, the Berk 135i is still quite streetable and would be a pretty decent street car, mild enough for comfortable daily driving! The car is a true statement that a fully streetable car can still easily be a winner in the hands of the right team.