Originally Posted by Mark II
Excellent write-up Tony
I think your estimate of a 20% loss through the transmission to be about right - so that's a VERY healthy increase in power and torque for a petrol motor and a great looking graph - good usable power.
BTW: Which urethane bushes did you use?
I think 20% is about right, as the ZF technical guys told me a few weeks ago that the 6HP19TU automatic gearbox suffers an approximate 18.1% drivetrain loss within itself. Couple that with the rest of the vehicle's drivetrain, that would equate to about 20% total...
The urethane bushes are actually built into the M3 suspension components. The front tension struts on the 335 use hydraulic bushes, which have a lot of play within them. The M3 variants use a solid poly bush and are a direct fit replacement - takes all of ten minutes to install once the car is up on a ramp.
The lower wishbones / control arms are much the same thing - instead of a sloppy rubber bush, it uses a big solid poly bush. However, the M3 control arms a couple of mm longer than normal, because they are designed to give 0.75degrees MORE negative camber than the 335i. They were an easy replacement too, although the car does need to be camber adjusted again after installation.