Quick Links: Engine Power Transmission Handling
Is there any reason to improve an E46 M3? Is it at all possible to make better a design that the M-Power engineers spend tons of money to create? Well, let’s look at it.
Firstly we need to understand the context in which we understand and consider improving the M3. We have to distinguish between design features and design errors.
The design features are the properties as they were meant to be. The design errors are the properties that did not turn out as they were meant to be. Example: The properties (handling) related to the bushings at the rear are (most probably) at intended. Naturally the M-engineers knew how to make the harder PU bushings, but they choose not to use hard(er) bushings. The choice was probably a compromise to suit the average potential M3 buyer. On the other hand the RACP weakness was surely not intended, thus a design error.
To improve on the design errors hardly needs any debate. Refer to M3 Issues.
To improve on the design features is an individual choice – sometimes just to suit personal preferences, at other times to turn a street M3 into a “track tool”.
Design improvements (except Track & Racing):
Engine power
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Transmission
Generally it doesn’t give much sense to improve the gearbox ratios or strength. The physical gearbox works fine and if shorter ratios are needed, this is easier achieved by changing the final drive ratio.
I’m not aware that the clutch has any issues and it seems good enough to handle reasonable engine tuning.
A particular issue is the choice between manual or SMG, where the SMG in reality is the exact same gearbox only operated via hydraulics and electronics. To some extend the choice is a matter of personal preferences, however the trend is that more “Hard Core” M3 owners prefer the manual.
To some an upgrade to CSL software satisfies SMG drivers.
More about SMG conversion to manual se here
For both manual and SMG a shorter ratio final drive will give the car more punch in acceleration. The standard crown / pinion ratio 3.62 may be changed to 3.91 or 4,1.
With the 4.1 (and nothing else changed) the 0 -100 performance will go from 5,1 sec to about 4,5 sec.
Se details: Improving final gear ratio.
It is a bit of a stretch to include Short Shift under the head line Transmission, but here it is: Short Shift
Restoration
Style (visual)
Redish Motorsports have made quite a lot of videos on RACP repairs and restorations - all of them very informative.
Here is one: The world’s BEST restored M3 CSL?
