Berk Technology's BMW 135I Time Attack Demonstrator

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.Berk Technology's BMW 135I Time Attack Demonstrator

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.

Berk Technology's BMW 135I Time Attack Demonstrator

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. 

Berk Technology's BMW 135I Time Attack Demonstrator

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.

Berk Technology's BMW 135I Time Attack Demonstrator

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.


Berk Technology's BMW 135I Time Attack Demonstrator
An HKS blow off valve and Evolution Racewerks charge pipe help protect from compressor surge on overrun.


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Thursday, August 26, 2010 11:01 PM
Jeff ----- That sounds alot more like it. I would love to see one running an less conservative tune simply because of the AEM water/methanol injection should curb the chances of detonation. One question I have is does direct injection leave less power on the table because of the already high compression ratio? I think it would be sweet to have a tech article explaining how direct injection- turbo motors are at tuning compared to port injection that is more common... Pros and Cons of each....
Mike Kojima
Mike Kojimalink
Thursday, August 26, 2010 11:47 PM
The disadvantages of DI are the lack of upgrade path for reasonable amounts of money and valve deposits.
Friday, August 27, 2010 12:18 AM
Thanks Mike!
Friday, August 27, 2010 1:11 AM
Best article ever! Of course, I may be a little biased...
OMG Its Weasel
OMG Its Weasellink
Friday, August 27, 2010 2:33 AM
BMW always amazes me with the complexity of their suspension and steering componenets.

what is the deal with that pushrod attached to the shock body on the front shocks? is that for the sway bar?
Friday, August 27, 2010 3:59 AM
I'm wondering about what that electronic rotary sensor looking thingy is that is attached to the control arm.

Gotta love the OEM flatbottom, good for gas mileage.
Friday, August 27, 2010 4:57 AM
Hmm seems like the HP is very conservative abit I have heard of people doing just reflashes on the 335i's and putting 330 hp down. But this car still sounds sweet. And I would love to know what all the weight they have stripped out brings the porker down too. Oh well Awesome right up as per usual..
Friday, August 27, 2010 5:08 AM
I'm confused. In RTA terms, full interior means dash, center console, front door cards?
Dusty Duster
Dusty Dusterlink
Friday, August 27, 2010 6:22 AM
Thanks for doing this feature. I'm purchasing a new vehicle in the spring, and the 135i is one I'm considering. I was concerned, though, that there was no aftermarket support for it, until now.
Mike Kojima
Mike Kojimalink
Friday, August 27, 2010 7:47 AM
Jeff2, it has to have all the glass as well, no lexan.
Jeff Naeyaert
Jeff Naeyaertlink
Friday, August 27, 2010 8:47 AM
rsmotors--thanks for the catch! Those power numbers were a little stale. Mike Bonanni just emailed me the current figures which i've updated in the article. On a conservative version of GIAC's Stage 2 tune thee car makes 379whp and 402lbs/ft torque on GIAC's Mustang dyno.
Monday, August 30, 2010 2:59 AM
Steve, I totally agree with you.
These days cars are packed with tons of accessories in the engine bay. Drop a dime in the engine bay, and it won't drop onto the floor.

All plastic covers help to "soffocate" the engine keeping it hot, very smart.

I have always believed that a cooler engine last longer and produces a bit more power. What's up with that?
Producing useless plastic covers only cost more to the companies.
It takes longer to access to the engine's vitals = more time consuming, so that you, or your mechanic will spend more time and money, and like I said, it traps heat in the engine bay.
What are those smart engineers thinking?

A side note: the BMW 135i weights about 3450 lbs. I don't see where the "relatively light" comes from.
Other than that, I do like the 135i. I wish it was 500 lbs lighter.
Monday, August 30, 2010 6:13 AM
Man am I glad I don't have to work around an engine bay this packed, it's reminiscent of a Z32. Nice intake design in theory but the placement on top (hot?) of the motor seems like an act of desperation to find *any* location to put the filters. Have to love those PAW-proof OEM BMW Exhaust Systems. They are so overbuilt I see 15 year old E36's with their original exhausts here in CT, and they're probably driven through Winter. The muffler wall thickness alone I have no problem believing 30 lb weight reduction.
Laura Heng
Laura Henglink
Wednesday, September 01, 2010 9:51 AM
Rsmotors - Direct Injection or DI for short is the next generation for fuel delivery in modern internal combustion engines IMO. It allows for very precise fuel delivery with extremely accurate timing of the fuel event compared to port injection. As Mike already mentioned one of the major drawbacks is that there is virtually no aftermarket stand alone ECU that has the ability to drive DI fuel systems. Motec has their M1 series of ECU's on the horizon that can control DI engines but we're still waiting on them to finish up the development.

OMG It's Weasel - The pushrod you see is an adjustable sway bar end link from Velocity Motorcars. The adjustable end link allows you to correct the sway bar geometry to remove any preload from the sway bar.

Spdracernut - that rotary electronic thingy is nothing more than a potentiometer for the headlights. Many cars with OEM HID's will have adaptive headlights that turn slightly as you turn the steering wheel, or aim themselves down as the car hits a bump so that you don't blind the drivers in front of you. There is a headlight sensor on the front of the car (left and right movement), and one in the rear (up and down movement).

Steve - I agree with you on the intake location. We plan on fabricating a new intake system that utilizes the stock intake box. **gasp**

JDMized - Fresh off the showroom floor the 135i weighed in ~3300lbs. This is a stripped down 135i without any factory options. The 135i is approximately 200lbs lighter than the 335i with the same option package. You get the same twin turbo motor and suspension in a smaller, lighter package. It is fairly easy to get a 135i under 3000lbs without cutting a single thing out of the car.

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