What would make more power in a nitrous car with stock L92's being spun to 7,000rpm?
We've done back to back testing on an engine dyno of a sheetmetal, single plane and FAST 90 on a 422 LSX w/ TFS 245's at 13.5:1 compression. The FAST crushed the sheetmetal and beat the single plain until it peaked around 6600. The single plain and the FAST hung close for another 200 rpm or so IIRC, and then kept on pulling to peak in the 7600 area. Sheetmetal just seemed to keep wanting more RPM. I would think that the 102 would have performed better on this big inch motor but at the time, it din't exist.To 7K, I'd take the FAST any day of the week. It'll make more power everywhere to about 6700.
Supercharged stuff can do the opposite because your cam timing may be sufficient enough to fill the cylinder to a xxx rpm, but with the manifold pressure it may be able to successfully fill the cylinder till a later rpm. Exh will take more to blow down also, but most supercharged plain jane stuff already crutches the exh lobe, and the change in cyl filling outpaces it. Alot of plain jane nitrous guys take their NA setups and strap a kit on it so it will be more pronounced as the exh end hurting it, if cammed correctly, it wouldnt change at all. Do what you need to do with the valve timing so the motor is happy where the intake manifold and cylinder head are best suited and its all irrelevantIf you take an NA engine that peaks at say 7000 rpm, and the exh lobe system etc is sufficient enough to blown down its 700 hp in the time given, stuff another 250 hp worth of combustibles in the chamber, what happens to the mass of spent gases? It goes up quite a bit, and you have same time to empty mo chit. Pumping losses go up.
There are alot more knowledgeable guy's on this forum than I on this subject but I believe the reason nitrous 'seems' to lower the powerband is because of the cylinder pressures enduced at lower RPM. Think about a 250 shot. It's adding enough oxygen to generate an extra 250hp. So at lower RPM there is more nitrous entering each cycle/second than at a higher RPM because your still spraying in the same amount of nitrous no matter what RPM your at. That added nitrous per cycle creates much much higher cylinder pressures. This is why nitrous car's generate such high TQ numbers lower in the RPM.I'd like to ask a slightly generalized question. So I've seen where a blower added to a combo can shift up the power band 500 rpms and more. I remember one time about 7 years ago talking to Jay Billingsley about nitrous and he said something about how nitrous can bring the power band down... Can anyone take my comments and react (constructively of course). I mean I know you'll want to spin a Briggs max N20 engine up there because those 4xx cid engines are SR and built to run at 8500 rpms etc, rpm makes power for NA. How does nitrous change the power band?