does the ability of an engine to rev (say 0-8k in 1 sec and in another 0-8k in 3 sec) relate in anyway to the energy within the exhaust? or is it relatively the same? I really don't know but im thinking the lower time would be more energetic (have higher velocity?) simply because it has to be forced out in a 1/3 of the time. Anyone know?

 

The ability of the engine to breathe related to exhaust would be based on volume of gas able to be expelled. thus bigger = better. Velocity only comes into the picture because high velocity creates a vaccum that sucks a bit more of the burnt air out of the cylinders. Plus higher velocity moves the gasses faster which keeps the temp up, higher temp = faster moving air, thus promoting better breathing. The motor thats pushing the air out faster will have a higher velocity than the slower one assuming both have the same dimeter exhaust. I'm not exactly sure what you were asking but maybe that helped you figure it out.

 

I could be wrong, but are you trying to figure out if you will have faster revs with a bigger exhaust ? If so, then exhaust size will not really play a role in how fast your revs move.

 

flywheel and centrifugal forces contribute to slow revs

 

im looking into a turboed k20 motor. Its gunna be full race application so im just exploring all aspects of the build up. Im thinking about upping the r.s ratio to around 2:1 in which case it would a rev happy critter, and assuming all things equal on a k20 except one with the 2:1 and another with the 1.62:1 (or whatever it is) if the exhaust is holding more energy with the 2:1 i'd be inclined to use that engine to spool the turbo. Of course the higher ratio would affect torque, but I assume the turbo would more than make up for that.