Well, I don't know much about the e21, but with any turbo the answer is that it depends how much boost you're going to run. If it's a small turbo and you're not running that high (~10 psi is pretty low), then you probably won't need to change anything. Also remember that it depends on what compression ratio you're running right now. I know that in the past there was a tuner who had a race car with a turbo M10 or M20. I only know a little about your engine, but it seems it has the highest compression ratio of all the e21 engines available. If it's easy and cheap, it might even be a good idea to go to the 323i's engine, as there are more people who've put a turbo on that.
I think you should ask someone who has a lot of experience with BMWs, especially the e21. |