Duke Togo

To build a good street car you have to tune for the 80/90% - I have seen so many cars destroyed either chasing cornering or power output limits I can't count them all. With racing it's different your priorities can change. In the Skunk2 Megapower thread Blacktrax has posted some dyno plots for ap2 tuning. There peak power is at around 8400 which is probably all you want to do with your mods.

https://www.s2ki.com/s2000/topic/896...r/page__st__50

s2kMyth

You dont need 8500 redline. Power peak is at 7100 in an ap2 even tuned.. ive been professionally tuned, and i shift at 7100 when running my car. its the sweet shift spot. my redline is 8672 or something like that and vtec is 4190..

JUSTINTHECOASTIE

No way that's completely wrong, a tuned ap2's peak power isn't 7100...search it heck look at mine in my sig....


@Duke 8.4k is about where I shift usually, except at auto-x events then I drag it out to about 8.6k. I'm sure cams will help with the power uptop, idk if I'm ready for that step yet. I haven't experienced any problems yet, knock on wood. I'm hitting another dyno(Realstreetperformace's) next Saturday, so I can get up to date pulls

nos4you

Please don't fill this thread with incorrect data. Just got back from my dyno and AP2's keep making power past 8K stock redline as shown in my graph. Not much more than stock but is certainly not losing power. So I have my Redline set at 8400 RPMs for the time being.

Duke Togo

In response to the other poster, every car is different and everyone has there mods and reasons when tuning. Vtec on my car is set at 4500 - I could set it lower and make a small bump in power but the oil pressure at low rpm's makes this a gamble. And yet some people will anyway, they will show how much more power there making and will end up with a much shorter engine life expectancy for it. And tell everyone that doesnt agree with them the dyno sheet is the gospel, the ability to live with the results is the main thing.

Today one of my friends offered me his car for a test drive, it's something like 500hp from an over boosted kraftwerks kit that he has been using for 3 years now. And as tempted as I was I remember track days watching boosted s2000's all over the place. Many of those people went N/A lost a bunch of power and were faster for it. So you have to do what's smart for you.

Duke Togo

In response to the other poster, every car is different and everyone has there mods and reasons when tuning. Vtec on my car is set at 4500 - I could set it lower and make a small bump in power but the oil pressure at low rpm's makes this a gamble. And yet some people will anyway, they will show how much more power there making and will end up with a much shorter engine life expectancy for it. And tell everyone that doesnt agree with them the dyno sheet is the gospel, the ability to live with the results is the main thing.

Today one of my friends offered me his car for a test drive, it's something like 500hp from an over boosted kraftwerks kit that he has been using for 3 years now. And as tempted as I was I remember track days watching boosted s2000's all over the place. Many of those people went N/A lost a bunch of power and were faster for it. One of them was something like 500whp and went down to 271 and raped everything gt3 on up on the banks at cali speedway. So you have to do what's smart for you.

ZDan

There *IS* value to being able to rev quite a bit beyond peak power rpm. It's already been touched on, but if you upshift at peak power rpm, you are losing way more than necessary in the next gear. Better acceleration in the lower gear revving beyond peak power rpm than in the next gear up. Upshifting from 2nd to 3rd at 8500rpm instead of 8200rpm (a mere 300rpm higher) would not only keep you pulling at very close to maximum horsepower for a longer time, it would also land you about 10hp higher up on the power curve when you do upshift.

Basically, you want to shift at a point where upshifting doesn't cost you power to the wheels, or at least minimizes the power lost. In an S2000, that pretty much means shifting at the redline/rev limit every time (i.e., you can't rev high enough to end up at the same power level in the next gear up). ~500rpm higher rev limit will definitely improve AP2 acceleration. And it's worth noting that peak piston acceleration is the same in an AP2 at 8500-8600 as it is in an AP1 at 9000.

nos4you

^^ Good stuff. Question is how much can our engines handle up in the R's. With a tune, I now have a lot more power in the 5-6k rpms. It is not as bad as factory where I had to be above 6k to be moving along pretty good.

Gernby

You're confusing power with torque. Peak torque is at about 7K for NA S2000's, but peak HP is about 8K unless something is wrong with the engine. If you work through the math (kinetics), you'll eventually prove that you need to shift AFTER peak HP in the RPM range to maximize accelleration across the whole speed range, unless you have a continuously variable transmission. If you do the same math for a CVT, you'll see that the CVT would need to change ratios as the engine maintained its RPMs right at the point where peak HP occurs.

As others have mentioned, when you have a full tune, then the benefit of increased midrange reduces the benefit of a higher redline. However, if you autocross or track the car, then the ability to occasionally stretch out a gear to avoid another upshift / downshift, then it can be very beneficial. I don't rev past 8200 often, but there are times when I might shift at 8250, and would be irritated by the rev limitter kicking in. I don't look at my tachometer while driving, and my ears aren't well-tuned enough that I can magically hit a 8199 shift point every time.

b.r.i.a.n.

i always rev beyond where peak hp is made. heck look at the stock ap1. peak power is made just after 8k rpm on a bone stock ap1 but the limiter is set well past that. the ap2 has the larger stroke hence the lowered rev limit but you can still rev them out. i usually rev them out to 8700 rpm.