You would be suprised what you can do by taking a week or two and stripping the whole motor down. I bought an 86 325e with a blown motor, and got another motor with the car. When we stripped the motor we just did little things to it.
Planed the head about 30 thousandths to boost compression to 9 1/2 : 1 from 9:1(i think that is the stock number.)
Re-honed the the cylinders with a 45 degree crosshatch
Shaved the intake edges to match the gasgets
Shaved teh trottle body door for better flow
shaved the exhuast manifolds to match the gaskets and open them up
Kept the same exhuast design because appearently with the e models exhuast was as good as it could get aside from the muffler. We replaced the cat converter with a flowmaster muffler then back to a ractive high flow muffler with a 4" opening.
now the motor that did 0-60 in just under 10 sec is now doing it in just under 8. Thats with no uprades all motor. Now the headers will make a differance, a chip will make a huge difference and cool air intake will be greatly effective. I really beg to differ that the e models can be performers.
i got and extra 700 or so RPMs out of it decent performance and still get 500km to a tank of gas
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