You’ll find here a list of things for the bmw 3 series (body e30) M42 engine, mainly for your vehicle, and the best part is – it will not burn a hole in your pocket. Certainly you want your BMW to really fly on the street, these are the things you need to do:
» Computer chip – most easy, basic and inexpensive modification for your auto. It usually run about $200-$300 and are very easy to install. A chip for m42 will bump the horsepower from 135 to 145 hp. The low-end torque is increased too. The chip widely increases the powerband of the engine, from 4600-6000 to 4500-6700.
» Flywheel – a big problem with the m42 engine was that it had BMW’s ‘dual-mass’ flywheel; yes, it weighs almost twice as much as a 325i flywheel (as the name would suggest). This is a big problem of m42. Do you understand why your 318iS’s 0-60 was so slow? Well, the flywheel is the answer. There are 2 options to fix this: replace with 325i flywheel/clutch or find an aluminum flywheel (about $700 but is very light, and requires no modification). The 325i flywheel requires a few other modifications with 318iS: 325i flywheel, 325i clutch, 325i pressure plate, 325i drive-pinion for the starter motor, and a ’78-’83 323 throw-out bearing. Replace all these with the 318iS parts and it bolts right together. After all is said and done, your 318iS will have a lot better acceleration in the first few gears, and deceleration will take place much quicker.
» Rear end gear – The 318iS is equipped with a 4.10 limited slip in a base complete set, but you can do better. The desired gears out there are the 4.27 (in E30 318i convertible 5 speed’s) and and the 4.45 (318i e36). The 4.45 is a wicked, wicked street gear but will stick your RPM way up there on the highway. The 4.27 is a better choice of performance and everyday use.
» Intake system – The 318iS stock air box works well, but a cone filter setup works better, but only if you have a well-built heat shield! Get a large K&N setup with the AFM adapter and all. While you are working on the intake, get the secondary plate of your throttle-body bored out 3mm to 57mm. This will make a difference.
Summary: You will find that with both a little time and a little cash, you can tune your 318iS to really perform. With these mods listed, you may find yourself taking out 325i’s in a straight line.
Read more at: old BMW cars blog – all about BMW cars.