Taking to modification like a bird takes flight, the 135i has become the BMW of choice among go-fast tuners like Berk Technology.
The 135i isnt just one of the best dual-purpose street and track cars weve built, says Brian Berk, owner of Berk Technology. Its the best.
Berk isnt alone in holding that opinion. In fact, its the prevailing view among aftermarket tuners, for whom the 135i Coupe is quickly becoming the BMW of choice. Not only is the car relatively inexpensive among BMWs, it also takes to modification like a bird takes to flight.
With the 135i, a few well-placed modifications and some suspension setup turn the car into a fierce competitor on the track, Berk says.
Though wed love to find that out for ourselves, we dont have a race track handy. Instead, well have to settle for the next best thing: Mulholland Drive above Malibu, California. About 70 miles north of Berks Santa Ana workshop, twisty Mulholland is remarkably deserted on this overcast weekday morning, and it should be perfect for exploring the capabilities of Berks 135i.
More power at the flick of a switch
Any enthusiast worth his or her salt knows that the 135is twin-turbocharged N54 3.0-liter six-cylinder engine puts out 300 horsepower and 300 lb-ft of torque at the crankshaft, or about 255 of each at the rear wheels. When you combine that kind of power with BMWs traditional chassis excellence, youve got a car that offers serious performance on both road and track.
To a tuner, however, a stock 135i Coupe is merely a great starting point. As capable as the 135i is, it can become much more so once its been modified to undo the compromises made at the factory to ensure road legality and DOT approval.
When we first started doing research and development on the vehicle, we noticed that the stock exhaust was one of the more restrictive pieces on the car, Berk notes. We know that forced induction motors can always benefit from more optimal exhaust flow, so we decided to start there.
First, Berk designed a pair of three-inch downpipes to improve turbo spool and horsepower and torque numbers, and gave them an internal ceramic coating like that normally found on pistons. The race version of this exhaust further locates its two mufflers in the center of the chassis rather than under the rear bumper, thus taking around 30 lbs. off the 135is rear end. By keeping all of the weight low and in the center, we improve weight distribution and lower the center of gravity of the car, Berk explains.
With the exhaust sorted, Berk moved on to the electronics, installing a Burger Motorsports Juice Box 3 device alongside the cars ECU. The Juice Box 3 gives us up to 80 horsepower and 80 lb-ft of torque at the flip of a switch, Berk says. Daily driveability is unaffected, and the device can be removed with no traces.
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According to Burger Motorsports, the JB3 (which works on all BMWs equipped with N54 engines, including those with BMWs latest software) requires no visible modifications such as external power or ground taps, and it wont trigger detection codes within the stock electronics. The latter is no doubt useful to owners whod like to keep their valuable factory warranties intact when they visit the local dealer for an oil change.
Another Burger Motorsports product is at work in this 135i: the Burger Motorsports O<sub>2</sub> sim. This compensates for the removal of the catalytic converters by tricking the ECU into thinking that theyre still in place and thereby keeps the Check Engine light from coming on. As Berk notes, such a devicealong with cat removal itselfis for track use only.
Elsewhere in the engine bay, Berk installed a free-flowing aFe intake and a Spearco Code 3 performance intercooler. The intercooler core is almost twice the size of the stock core. It greatly reduces charge air temperatures and keeps detonation in check, says Berk.
With the modifications complete, the car was tested on the dyno, where Berk says it delivered 308 horsepower and 315 lb-ft of torque at the rear wheels.
And thats on the low-boost setting, he says, referring to the JB3s optional 12-13 psi boost setting, which can be switched to 13-14 psi from the cockpit. We havent felt the need to tap into the high-boost settings yet.
Slide in and push the start button
To find out how the changes work on the road, we slither into the cars one-piece Sparco Pro 2000 racing seat, which isnt as comfortable or as convenient as the stock bucket but holds the driver firmly in place while shedding significant flab.
The factory front seats weigh an astonishing 53 lbs. each, Berk says. The Sparcos, on the other hand, weigh just 18 lbs. eachswap both front seats and a weight savings of approximately 70 lbs. can be realized.
To accompany those racing seats, Berk has installed a set of Sparco harnesses attached to a pair of his own harness bars. Strapping ourselves in, we push the Start button and ignite the N54 engine. It lights up with a raspy bark, which even at idle sounds far more purposeful than stock. Berk wasnt kidding about that exhaust being full race-spec: Once on the move, this car makes plenty of noise.
The extra sound goes with more forceful acceleration: Get on the throttle aggressively anywhere above 2,000 rpm and the little coupe rockets forward enthusiastically.
When we lift for an upshift, the blow-off valve makes an audible sshpit! before we grab the next gear and continue rapidly forward. The whole affair would probably be too loud for full-time street use, but it sounds terrific nonetheless. A lusty, hard-edged howl is present throughout the rev range, with only an annoying resonance at low rpm to interfere with our enjoyment. From the passenger seat, Berk tells us hes still developing the exhaust note.
As well as more noise, the Berk 135i is also making more power, and delivering that to the rear axle is the job of a Quaife limited slip differential. This was sourced from HP Autowerks with a lower final drive ratio of 3:46:1 (3.08:1 is stock), which means the Berk 135i now has the same rear-end ratio as an automatic-transmission 135i.
The diff gives us added acceleration without putting any additional stress on the engine or drivetrain, Berk says. The gearing also allows us to maximize the powerband on the track, where its most important.
It certainly works well during our canyon workout, allowing the 135i to rocket out of corners and making it much easier to keep the engine in the heart of the powerband.
Traction control
To keep the 135i in contact with the asphalt, Berk has chosen a set of Federal 595RS-R Track Sport tires that measure 255/35-18 front and 265/35-18 rear. Though these Taiwanese tires arent particularly well known in the U.S., theyre widely used on race tracks in Japan and Australia. On the Berk 135i, theyre mounted on 18-inch D-Force EmPower rims that save considerable unsprung weight over the OEM wheels: The 8.5-inch front weighs 19.3 lbs., the 9.5-inch rear just 20.9 lbs.
Upstream, four tried-and-true KW Variant 3 coilovers handle the suspension duties. With their stiffer springs and lower ride height, the KWs reduce most of the 135is body roll, keeping the chassis buttoned down without making the ride unduly harsh. Only the occasional pothole or rough patch of asphalt upsets the chassis composure, an impressive feat with full-on coilovers. The setup also reduces the frustrating, speed-robbing understeer that plagues the 135i in stock form, replacing it with neutral handling that can shift toward controllable oversteer with a brush of the throttle pedal.
KW did a great job in designing a suspension setup that is compliant enough for the street but will still go race-car fast on the track with a few quick adjustments, Berk says.
Since the 135i already comes with six-piston Brembo brakes up front, Berk limited the changes in that department to Hawk HT-10 pads and ATE fluid. With that, the brakes are more than up to the task of slowing the 135i on the street, and Berk says they hold up impressively on the track.
Thats true of the 135i itself, as well. With a few well-chosen upgrades, the smallest BMW can be transformed into a track-worthy car that can lap at respectable speeds all day and then drive home in air-conditioned comfort.
The ultimate goal of the project was to build a wolf in sheeps clothing, a street car that could run with the best in a racing environment with nothing more than a few adjustments to the dampers and a brake pad change, Berk explains.
While this car isnt exactly wearing sheeps clothingthe V-Fiber body kit and bold graphics over Alpine White paint make it look like it got lost on the way to a sports car raceeven such obvious modifications cant diminish the versatility that has made the 1 Series so popular.
As Berk says, this 135i is a BMW turned up to 11.
The 135i isnt just one of the best dual-purpose street and track cars weve built, says Brian Berk, owner of Berk Technology. Its the best.
Berk isnt alone in holding that opinion. In fact, its the prevailing view among aftermarket tuners, for whom the 135i Coupe is quickly becoming the BMW of choice. Not only is the car relatively inexpensive among BMWs, it also takes to modification like a bird takes to flight.
With the 135i, a few well-placed modifications and some suspension setup turn the car into a fierce competitor on the track, Berk says.
Though wed love to find that out for ourselves, we dont have a race track handy. Instead, well have to settle for the next best thing: Mulholland Drive above Malibu, California. About 70 miles north of Berks Santa Ana workshop, twisty Mulholland is remarkably deserted on this overcast weekday morning, and it should be perfect for exploring the capabilities of Berks 135i.
More power at the flick of a switch
Any enthusiast worth his or her salt knows that the 135is twin-turbocharged N54 3.0-liter six-cylinder engine puts out 300 horsepower and 300 lb-ft of torque at the crankshaft, or about 255 of each at the rear wheels. When you combine that kind of power with BMWs traditional chassis excellence, youve got a car that offers serious performance on both road and track.
To a tuner, however, a stock 135i Coupe is merely a great starting point. As capable as the 135i is, it can become much more so once its been modified to undo the compromises made at the factory to ensure road legality and DOT approval.
When we first started doing research and development on the vehicle, we noticed that the stock exhaust was one of the more restrictive pieces on the car, Berk notes. We know that forced induction motors can always benefit from more optimal exhaust flow, so we decided to start there.
First, Berk designed a pair of three-inch downpipes to improve turbo spool and horsepower and torque numbers, and gave them an internal ceramic coating like that normally found on pistons. The race version of this exhaust further locates its two mufflers in the center of the chassis rather than under the rear bumper, thus taking around 30 lbs. off the 135is rear end. By keeping all of the weight low and in the center, we improve weight distribution and lower the center of gravity of the car, Berk explains.
With the exhaust sorted, Berk moved on to the electronics, installing a Burger Motorsports Juice Box 3 device alongside the cars ECU. The Juice Box 3 gives us up to 80 horsepower and 80 lb-ft of torque at the flip of a switch, Berk says. Daily driveability is unaffected, and the device can be removed with no traces.
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According to Burger Motorsports, the JB3 (which works on all BMWs equipped with N54 engines, including those with BMWs latest software) requires no visible modifications such as external power or ground taps, and it wont trigger detection codes within the stock electronics. The latter is no doubt useful to owners whod like to keep their valuable factory warranties intact when they visit the local dealer for an oil change.
Another Burger Motorsports product is at work in this 135i: the Burger Motorsports O<sub>2</sub> sim. This compensates for the removal of the catalytic converters by tricking the ECU into thinking that theyre still in place and thereby keeps the Check Engine light from coming on. As Berk notes, such a devicealong with cat removal itselfis for track use only.
Elsewhere in the engine bay, Berk installed a free-flowing aFe intake and a Spearco Code 3 performance intercooler. The intercooler core is almost twice the size of the stock core. It greatly reduces charge air temperatures and keeps detonation in check, says Berk.
With the modifications complete, the car was tested on the dyno, where Berk says it delivered 308 horsepower and 315 lb-ft of torque at the rear wheels.
And thats on the low-boost setting, he says, referring to the JB3s optional 12-13 psi boost setting, which can be switched to 13-14 psi from the cockpit. We havent felt the need to tap into the high-boost settings yet.
Slide in and push the start button
To find out how the changes work on the road, we slither into the cars one-piece Sparco Pro 2000 racing seat, which isnt as comfortable or as convenient as the stock bucket but holds the driver firmly in place while shedding significant flab.
The factory front seats weigh an astonishing 53 lbs. each, Berk says. The Sparcos, on the other hand, weigh just 18 lbs. eachswap both front seats and a weight savings of approximately 70 lbs. can be realized.
To accompany those racing seats, Berk has installed a set of Sparco harnesses attached to a pair of his own harness bars. Strapping ourselves in, we push the Start button and ignite the N54 engine. It lights up with a raspy bark, which even at idle sounds far more purposeful than stock. Berk wasnt kidding about that exhaust being full race-spec: Once on the move, this car makes plenty of noise.
The extra sound goes with more forceful acceleration: Get on the throttle aggressively anywhere above 2,000 rpm and the little coupe rockets forward enthusiastically.
When we lift for an upshift, the blow-off valve makes an audible sshpit! before we grab the next gear and continue rapidly forward. The whole affair would probably be too loud for full-time street use, but it sounds terrific nonetheless. A lusty, hard-edged howl is present throughout the rev range, with only an annoying resonance at low rpm to interfere with our enjoyment. From the passenger seat, Berk tells us hes still developing the exhaust note.
As well as more noise, the Berk 135i is also making more power, and delivering that to the rear axle is the job of a Quaife limited slip differential. This was sourced from HP Autowerks with a lower final drive ratio of 3:46:1 (3.08:1 is stock), which means the Berk 135i now has the same rear-end ratio as an automatic-transmission 135i.
The diff gives us added acceleration without putting any additional stress on the engine or drivetrain, Berk says. The gearing also allows us to maximize the powerband on the track, where its most important.
It certainly works well during our canyon workout, allowing the 135i to rocket out of corners and making it much easier to keep the engine in the heart of the powerband.
Traction control
To keep the 135i in contact with the asphalt, Berk has chosen a set of Federal 595RS-R Track Sport tires that measure 255/35-18 front and 265/35-18 rear. Though these Taiwanese tires arent particularly well known in the U.S., theyre widely used on race tracks in Japan and Australia. On the Berk 135i, theyre mounted on 18-inch D-Force EmPower rims that save considerable unsprung weight over the OEM wheels: The 8.5-inch front weighs 19.3 lbs., the 9.5-inch rear just 20.9 lbs.
Upstream, four tried-and-true KW Variant 3 coilovers handle the suspension duties. With their stiffer springs and lower ride height, the KWs reduce most of the 135is body roll, keeping the chassis buttoned down without making the ride unduly harsh. Only the occasional pothole or rough patch of asphalt upsets the chassis composure, an impressive feat with full-on coilovers. The setup also reduces the frustrating, speed-robbing understeer that plagues the 135i in stock form, replacing it with neutral handling that can shift toward controllable oversteer with a brush of the throttle pedal.
KW did a great job in designing a suspension setup that is compliant enough for the street but will still go race-car fast on the track with a few quick adjustments, Berk says.
Since the 135i already comes with six-piston Brembo brakes up front, Berk limited the changes in that department to Hawk HT-10 pads and ATE fluid. With that, the brakes are more than up to the task of slowing the 135i on the street, and Berk says they hold up impressively on the track.
Thats true of the 135i itself, as well. With a few well-chosen upgrades, the smallest BMW can be transformed into a track-worthy car that can lap at respectable speeds all day and then drive home in air-conditioned comfort.
The ultimate goal of the project was to build a wolf in sheeps clothing, a street car that could run with the best in a racing environment with nothing more than a few adjustments to the dampers and a brake pad change, Berk explains.
While this car isnt exactly wearing sheeps clothingthe V-Fiber body kit and bold graphics over Alpine White paint make it look like it got lost on the way to a sports car raceeven such obvious modifications cant diminish the versatility that has made the 1 Series so popular.
As Berk says, this 135i is a BMW turned up to 11.
