BMW e90 335i Track Development Car
After years of racing NA BMWs in series such as SCCA, BMWCCA, NASA, World Challenge, and Grand Am (now IMSA), 3DM has embarked on a new mission to develop E9X 335i track and race products.
Visit any BMW DE or club race and you will be hard pressed to find a forced induction (FI) powered car, the normally aspirated (NA) e36s and e46s rule the roost at these events. With both of these chassis ending production well over a decade ago, what is next for a dedicated track toy? Typically, the subsequent BMW chassis model’s standard 3 series was essentially as capable as it’s predecessor’s M3. For example, the e36 325i closely matched the capabilities of the e30 m3 and the e46 330i closely matched the capabilities of the e36 M3. Unfortunately, this was not the case when the e90 came into production, the e90 330i simply cannot match the e46 M3 on the track. With E9X M3 prices hovering above $20k, it is hard to swallow that entry point to a dedicated track car. Enter the E90 335i N54 turbo cars…
Stay tuned in as the development process progresses. We hope you enjoy following this journey and hopefully it will help your e9X track car project as well.
We actually aren’t new to the e9X and N54 platforms. We campaigned an E90 328i in Grand Am (now IMSA) and have run a 335i and 1M in the TireRack One Lap of America as well as many other track events. Our Project E89 Z4 3.5i is N54 powered as well.
Our benchmark for power output is the e46 M3. A well prepped s54 from an e46 M3 will make roughly 350 reliable WHP. To go beyond that requires an extensive internal build and if the motor goes boom, it can quickly become a wallet breaker. This is where we believe the N54 will shine as a target of 450-500 WHP will easily be accomplished with bolt on parts. In this case, if the engine goes boom it’s not a wallet breaker to replace the long block and get back on track. Having said that, the most difficult pieces of the project puzzle will be to achieve drivabilty and longevity. Reducing lag and linear power curves are paramount for drivability on a road course. Keeping the motor cool and the accessory components running well within their operating threshold will be essential.
The suspension on the e9X chassis is very complicated and the goal is to explore the suspension in detail. The front suspension is unlike its 3 series predecessors, it's actually an iteration of a design BMW has been using for decades on the 5 and 7 series. The front control arm and tension arm are separate which allows for a dynamic steering axis, separate roll center, and anti dive control. The rear suspension was a new development from BMW. It is actually designed to have multiple toe curves depending on the load applied which is accomplished by rubber bushings. In fact, if you replace every bushing with a solid ball joint, the suspension will be locked into place and will not articulate.
The OEM MK60 e5 ABS is fantastic on these cars, however our experience has shown us the bias is heavy to the rear. This works well on street cars but is not optimal on a track car. We will be digging in to the ABS coding to remove some of the “nannies” and change other parameters.
Drivetrain: Our friends at diffsonline have spent years perfecting differentials and transmissions for track use and we have used them on every car we have ever raced. In addition, those who drag race these cars have also proven the transmission syncros and gears can handle the shifting and power respectively.
Aero: The goal is to keep this car streetable to where it could still be driven to work. Therefore an Msport bumper and maybe a trunklid spoiler will be it for aero development. Wings and splitters would be a little gaudy in our opinion.
Safety: Since there will be significant track testing some safety equipment will be required. A simple 4 point cage, race seats and harnesses will be installed. This is not ideal for a street car but safety is paramount.