| Sorry to chime in so late!
Couple things.. well first of all, the Euro E36 M3 is actually more akin to the S14 with 2 more cylinders than the S54 motor. The S54 is a whole new era of design. The Euro motor is actually more old-school than the US in some respects..
As far as tuning the US motor - there is great power potential without breaking the bank. There is a very definite point where you are simply trading reliability for that few extra horses. For example, narrow stem race valves will get much hotter than standard which can lead to problems. As well as items like titanium retainers- especially on a 4-valve head where the retainer is very small. We won't even install those on a street motor.
A setup like mine? Well that cost depends completely on what you're starting with. If you've already got a 3.2 then that's a bonus, but then you need an OBDI swap. Of course a 3.0 would require a new crankshaft..
The powerband with stock cams is really quite nice. It pulls hard down low, and the top end is certainly sufficient. I'm planning on doing cams down the road regardless of what long-block i'm running just because i've had the car with stock cams for so long and because i will be tracking the car more.
The 250whp/221wtq i'm putting down at present is not even all she's got. My AFR's are pretty choppy and there are several peaks/troughs. My revised AA software should fix it. In addition, my motor could use some headers.. and maybe a big-bore throttle body and pullies.
The ultimate street motor that retains reliability would be, in my opinion, a 3.2L bottom end with 11:1 custom pistons. Full headwork with oversize intake valves. Schrick 264/256 camshafts with the requisite injectors. An extrude honed Schrick aluminum manifold with 3.5 MAF and CAI. And whichever header works well with the powerband you're looking for.. 12lb flywheel, Sachs clutch/plate. Fan delete, pullies, etc. And some DYNO TUNING! That should be good for 270+whp and 235+wtq. Granted it would be pretty pricey.
I'd be happy to quote any configuration if you like..
Bottom line:
US S50 is a terrific motor. The Euro counterpart is very hot, but you certainly pay for that in parts prices and tuning options. The Euro motor is also about 20lbs heavier.  |