[jluetjen]

Hi BK; it's great to hear from you again. Starting at the bottom...

1) a 2.7E with 36 mm ports and MFI. Another poster on this BBS built an engine like this for autocrossing and it was stronger than a 2.4E from 2100 RPM up to about 5700 RPM. After that it ran out of steam quickly. Compared to the S cam, the E cam has lower lift, which made for higher gas flows at lower revs. But once the engine speed picked up, the lift limited the absolute gas flow, resulting in the torque dropping like a stone after that. Compared to the same engine with S cams (ie. a 2.7RS), the 2.7RS won't start to be generating that kind of torque until at least 4000 RPM.

2) As far as a 2.4E with 2.2E or 2.2S pistons -- I think that you need to look at the static CR of each case to make sure that you'll be able to get gas for it. Unfortunately I can't find the spreadsheet that I did, but if I remember it correctly the key points look like this...

- The T, E and S engines end up having comparable static CR's. This is because even though the S has the highest CR pistons, the high-lift/long duration cam closes the intake valve later than the E cam. If you calculate the CR from when the intake valve closes, you'll find that in each case the CR is about the same. Now if the factory engine runs on 91 octane, and you switch to the next higher CR piston without changing the cam -- I'd expect that you'll need to jump a grade is gas. If you go two steps (such as E cam with 2.2S pistons) you may find it hard to keep all of the ponies inside the cylinder given the CR. You could back off on the ignition timing some, but that will increase your engine temperatures. You could move the cam timing later, but that may cause other issues with clearances. The best solution to this would be to twin-plug -- but that takes more $.

- All of the previous points are true, but our engines are dynamic - not static and will often operate at different RPM levels. Because of the intake and exhaust harmonics there will be an engine speed where the intake charge will get compacted into the cylinder resulting in the cylinder pressures increasing. This will happen at the peak torque engine speed. Now imagine what will happen to your 2.4E with 2.2S pistons in it running on street fuel when this happens. Short of having a fully mapped ignition, it would most likely be difficult to adjust the ignition timing to avoid detonation that that point, while not being over-retarded elsewhere in the RPM range. I would think that going one step will be fine if you switch to 93 (or better yet 94 or 95 octane if you can find it), but going further than that will require very specific tuning.

Ultimately it depends on where you want to put the peak torque. E cams will make the engine pull from 2100 to 5200. S cams will make it pull strongest from about 3700 to 6100. One option might be to use something like the MOD-E cam which has more lift and duration than the factory E cams, but not as much as the factory S cams. That should put the torque curve right in between those two options.

That's my $0.02 for now.