pettybird

the S still had higher compression--the highest of the 924/944/968 range.

mine is great around town--the extra gearing in the transmission helps out a lot.

67King

Which is exactly what I said:

Honda will actuate 4 valves with one cam, and often adds VCT to the DOHC motors. As we are effectively talking about 2V versus 4V chambers, the Ford example (of the NA versus S) are much more appropriate.

The problem with just throwing out numbers is that you are taking extrapolation to an extreme. An 80mm valve compared to a pair of 34mm valves is like comparing a 20,000RPM engine to a 5,000RPM one, rather than a 7500RPM engine to a 6000RPM one. Yeah, at such an extreme, it will make a big difference, as other things can't make up for it. But within the band we are talking, other things do.

Think about this. What do cam events look like at lower RPM relative to higher RPM? They are more advanced. That will work to slow down the velocity of the air (relative to a retarded cam). I don't disagree with you that velocity is always important. But again, when you are looking at the size difference we are talking here, the other things are much more dominant. The biggest impact (within reason, here) on the torque curve will be the L/D of the primary runner in the intake manifold. At lower RPM, you increase torque by tuning, thus making the air charge more dense. At higher RPM, tuning is less prominent, and you increase your torque by getting the velocities up there to a point where the ram affect (i.e. the air's momentum will keep it filling the cylinder, even after the piston moves past BDC) takes place. Yes, it all takes place across the board.

Anyway, I'm done.