Sat Aug 08, 2015 4:49 pm
In terms of different engines, 325's had "high compression" and "low compression" m20's (all being relative, the high CR isn't really that high). Pre-facelift had high comp, running the older motronic system, facelift had low comp, with better engine management. The better engine management can be fitted to high comp engines for increased performance.
In terms of what is best for modifying for power, nothing really. BMW properly engineered the lumps, so there's no simple bolt ons that will yield decent performance. Looking at the m20, you can do some headwork, cams etc and get a bit more power. You can also build strokers, 2.7's and 2.8's being the most common, but I have seen 3.1's and if memory serves a 3.2 before. The problem is it's very expensive to do so most people looking for power decide to stick something else in.
A common swap is the m5x swaps. An m52 with m50 inlet and a map is around 220hp, and to do properly will cost between £1 and £2k.
m30's are also common and look more period in the bay. But they are old engines and weigh a lot, and have poor specific outputs, but a decent load of torque. Also Rav will start sexting you if you go down that route, something best avoided.
Leaving m3's out of the equation, the most desirable e30 will always be a 325i in 2 door flavour. Sport's being even more desirable. That being said, a clean 2 door is a lovely thing and I prefer the lines to a Tech 2 these days (I own a Tech 2 and and SE)
