One way to "ball park" it a little is to figure out when the engine feels like it is "coming on cam".
So you start out at 1500 RPM in 2nd gear and smoothly give it full throttle. When does it start to run cleanly? When does it really start to PULL with a capital "P" (peak torque engine speed)?
My experience is that for the stock Porsche cams, the answers would be about as follows:
Cam.....Pulls cleanly.....PULLS!
T...........1500...............4200 RPM
E...........2000...............4500
S...........2500...............5200
SC.........????................4200
Now of course this will all depend on the level of tune of the engine, the configuration of the motor (if it has been rebuilt) and such, but it should put you in the ball park.
Basically, if you can potter away at 1000 RPM cleanly -- you don't have "S" cams!
