3DM E90/N54 Track Car Build

[email protected]

Platinum Vendor
Jun 4, 2018
I actually have two build threads to create about e90/N54 track cars. An HPDE/Time Trail car, which this thread is about, and a dedicated racecar. I will create another thread about the racecar when the appropriate time comes.

I hear it all the time, if you want a reliable and affordable BMW track car you have to go e36/e46. Well, those cars won't last forever. I’ve been building and racing BMWs for over 20 years including e30s, e36s, and e46s and decided it was time to move on. After assisting others with their N54 based track cars over the years, I decided to take the plunge to develop my own n54 based track car, a 2007 e90 335i.

This goal of this build thread is twofold, to showcase the capability of an N54 powered E9X on a track and to utilize the fantastic collective knowledge of the Spoolstreet N54 community. Hopefully we can solve some of the problems that will allow the N54 to shine as a track going BMW motor!

I'll start with some high level build thoughts...

Must remain streetable: This is being built as a dual-purpose car, to drive around town for fun and at the track. This also allows for testing of parts at any time, not just at the track.

Target 450 WHP: We know the N54 can make big power, it has been proven over and over. The goal of this build is not big power, it’s a RELIABLE 450 WHP. If reliability can be solved, we have a winner. Jumping ship from an E36 or E46 M3 track car is a no brainer at that point because no amount of money will allow those cars to obtain 450 WHP and the torque to match.

Must use pump gas only: E85 is scarce at race tracks and carrying fuel to the track is a major pain in large quantities.

KISS: Keep it simple stupid… No aftermarket or piggy back DMEs. Keep as many things as possible bolt on, however some fabrication is OK.

Cooling: This is the first and foremost problem with the N54 in terms of track use. Yes, there are aftermarket radiators, auxiliary radiators, and altered target temp settings but they simply don’t keep the motor cool enough for track use. The solution to the cooling problem is a two step process. First, the DME software needs to be altered which will allow for the second process of designing proper cooling system hardware. Unfortunately, my expertise does not lie in the software side of the equation which is where I hope the Spoolstreet community can help. In fact, a lot of this has been covered in a thread I started about the cooling system here: N54 Cooling – Temp Control Logic

With the fantastic help of @RSL we concluded that the pump is running 100% to try to target a coolant temp. We can’t change the thermostat or water pump as the DME will throw codes and go into reduced power mode. If anyone knows a way to remove this so that we can try other aftermarket water pumps and thermostats that would be fantastic!

Turbos: Definitely staying with a twin setup. One major factor of track driving is the drivability of the car itself. While most of my experience is driving/racing NA motors I do have some experience driving both single and twin turbo N54 setups on the track. This topic is of course highly debatable but my experience is that twins are the way to go. There is simply too much lag with a single turbo and it makes driving at 10/10ths very difficult.

Suspension: Dampers are a modified Ohlins Road and Track setup. I’ve been using Ohlins dampers for over 10 years on various other BMWs, well before the current Road and Track system was released. In fact, I made my own “Road and Track” setup for the e46 M3 using the previous Ohlins Sportline that I modified (threaded perch and re-valved) in conjunction with an Ohlins STJ motorsport damper.

Example 335i Setup:

To me, Ohlins are preferred because of their motorsport heritage and attention to quality and design. Things like the inverted front strut, Dual Flow Valve, and temperature compensation bleed valve make them the perfect solution for a dual-purpose road and track car. I have been testing and developing two E9X Ohlins kits over the past few months and Ohlins will be shaker rig testing the results in a few weeks. One is a 335i specific revised Road and Track kit and the other a “Dedicated Track” kit with both M and Non M fitments. I will explain these in more detail in another thread to come. Below is an e46 M3 in action on the shaker rig.

In addition to developing the Shock/Spring packages, I’ve been working on the rear suspension kinematics. I’ve bench top mocked up both the 335i and the M3 suspensions for an in depth comparison of the camber and toe curves and other pieces of the puzzle. Again, more to come in another thread about all of this in detail very soon.

Data: I have been using AIM for many years and I chose the AIM Evo 5 for this car. The Evo 5 is a small logger that uses an additional add on dash called the GS-Dash. Keeping the logger separate from the dash allows me to collect data while on the street without having the dash in front of the OEM instrument cluster all the time. When at the track I put the dash in front of the OE cluster so I have warning and shift lights.

In addition to the normal analog sensor inputs, GPS data, and X Y Z axis accelerometers, the AIM also has CAN inputs to allow logging many parameters already being collected by the car itself via PT CAN such as brake pressures, steering angles, etc. Unfortunately, since it only logs parameters broadcast over CAN, this means detailed engine parameters like WGDC can’t be logged. This is of course where MHD comes into play. Now the issue is having two loggers to deal with which is a topic that I intend bring up in another thread.

Differential: The differential is major part of the equation for an E9X track car. I will be swapping out the open diff for a true limited slip. I have been using Dan at diffsonline for 20 years and he knows his stuff. He does it all day every day and knows how to setup a diff for track use.

E-diff side note: I don’t believe my car has the E-diff but whether it does or not I wouldn’t want it as it uses the braking components to accomplish its task. Fine for a street car but on a track car the LAST thing you want is the brakes doing something other than, well… braking.

Aero: Other than an M Sport bumper upgrade the aero will be left alone. It’s a street car. I might put a trunk lip spoiler on, we’ll see. The M sport bumper is part of the cooling equation, the stock 335i bumper air inlets have too small of a surface area for proper cooling.

Safety: A non-intrusive 4 point cage will be installed with 6 point harnesses for the driver and passenger. I have a pure race seat with halo that I intend to swap in and out when I go to the track. It’s a lot of work to swap in and out but I don’t want to be sliding around in a stock seat, it’s just not safe.

Anyways... much more to come. I hope you enjoy this thread and hope it helps with any of your E90/N54 adventures. I'm looking forward to the knowledge that I gain from this community and I especially want to thank @doublespaces for providing us with Spoolstreet.com!

@[email protected]
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Jun 27, 2017
Sweet, I'm really looking forward to seeing this all come together. I had a lot of the same stuff in mind for my own car.
Dec 1, 2016
New York
In for updates.

See here for a users technical breakdown of Ohlin R&T (fe1rx ): https://www.1addicts.com/forums/showthread.php?t=956039

Might save you some time when you come across various issues... Like, front spring length, rear strut length, etc.. Curious as to what spring rates you'll end up choosing based on your suspension and shaker rig testing.
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Jan 28, 2018
Barry installed Ohlins R&T on my much-tracked 1M and has made many other improvements to it. He really knows what he's doing!


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