oi...
Robin - you thinking up changing cams? Let's break it down a bit.
- Schrick cam, new billet we believe or welded lobes. Good reports up to a 284 with stock compression. JoeS reports that the torque curve seems to be pretty broad from about 3k RPM on. Lobe centers unknown but likely similar to stock due to torque curve. JoeS has a ported head and 3.76 rear end and a e28 (22lb) flywheel if I recall. MAF conversion.
- IE "284" cam. Grind off the stock cam. Martin has this one and it seems to run well on a non-ported head. Torque curve seems to pickup at 2.5 to 2.8k +. Lobe centers must be about the same as stock as it's a grind with no weld. Martin's running a non-ported head and 3.64 rear end with a 15 lb flywheel. MAF conversion.
- Metric Mechanic "Rally Cam" - welded lobe and ground cam to Jim R. spec. Designed mostly for his 3.7 sport motor which is overbored and with 10:1 compression. Lobe centers likely increased beyond stock as torque curve has moved higher. In a stock compression motor with 4 degrees advance, car is peaky and comes on-cam hard about 4k RPM, very noticable. Off cam performance is driveable but you miss the midrange torque of the IE 284. I'm running a ported head, 3.46 rear end and 22lb flywheel. MAF conversion. Likley not the best choice unless you plan to up the engine compression.
The Schrick and MM cams are likely about the same price. The IE 284 cam is the cheapest. I seem to recall the BavAuto engine having either a 272 or 276 cam. Stock is like 268.
Jeff
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy