We set out with the goal of taking the Z4 where it has not been before. To push it to the limits but still retain the ability to drive it every day. And we have achieved that.
We started this one of a kind build at the wheels. Something subtle, but not underwhelming. Something lightweight, but not designed for track use only. To us, the 19” O.Z. Racing Leggera HLTs were a perfect match with their factory look and racing heritage. We also needed tires that would allow the wheels to put all the power down to the pavement whether on or off the track. Michelin Pilot Super Sport tires wrap the anthracite grey Leggeras and provide superb grip for aggressive driving styles.
Most of the work has been put under the hood of this roadster. Being a Dinan Authorized Dealer we have the resources to add some serious power to the already quick Z4. The Dinan Stage 3 Performance Engine Software dramatically increased the engine output.
“The Z4 went from 300 hp to 406 hp at 5700 rpm and peak torque increased from 300 lb-ft to 430 lb-ft at 4300 rpm!”
This however, was not a quick re-flash and drive away situation. These power numbers required supporting mods to get the most out of the tune without damaging the engine. So, we installed a larger intercooler (double the factory capacity) which let the turbos perform more efficiently and provide a cooler charge to the engine.
With more power comes greater wear, unless the proper precautions are taken. High engine temperatures and long track days equate to higher oil temps. The Dinan oil cooler was installed in order to keep the engine oil from overheating causing loss of viscosity, lubrication issues and premature engine wear.
We also addressed suspension and handling since this Z4 was aimed at being a track/daily driver project. The factory suspension was dropped for Bilstein mono-tube, inverted gas pressure shocks and Eibach springs. This combination was road tested and fine-tuned to compliment one another as well as drop the car an over and inch below stock height for a more aggressive appearance. A Turner Motorsport front aluminum strut brace, also know as a "stress bar", was also added to help minimize chassis flex during aggressive cornering. This helps keep the tires planted square on the road and delivers traction when you need it most.
In order to put down all the power to the rear wheels effectively, we decided that the Michelin Pilot Super Sport tires were not going to be able to do all the work themselves. So, we decided to introduce a specially designed WaveTrac LSD (Limited-Slip Differential) to the rear end instead of the factory open differential. This not only increased the acceleration and traction of the Z4 off the line, but it also improved the final drive ratio allowing the car to accelerate faster through the gears.
Since we wanted to build a car that could still be driven every day, we did not want to have an obnoxiously loud exhaust. We knew it wouldn't be pleasant to use on a highway commute. Super Sprint Performance Mufflers, coupled with their X-pipe, provides a low purr at idle while still sounding aggressive at wide open throttle.
To top off the build we added our own little touches to the exterior of the car. The standard silver kidney grills were replaced by high gloss black kidney grills straight from BMW. Mirror caps, roll bar covers, side accents and lower grill vents were all professionally painted in a high gloss black paint. We also removed all the Z4 badging.
BMW does not currently offer an M Model for their Z4 Series. Thanks to combined efforts of our incredible Isringhausen BMW techs and the expert engineers over at Dinan, we think we've created an unofficial 2015 BMW Z4M. Let us know what you think. If you're interested in this car or perhaps having your own car built out, feel free to reach out to us at motorsports@isringhausen.com