And I assume this is why the Grand Am engines all run dry-sumps.

I just saw a few days ago a 370 dyno sheet going to 8100. The car fell flat on its face after 7600 rpm. Seems pointless anyways. I'll try to find the pic.

I know some guys that rev'd their DE oil pump over 9000 on the dyno, and it even made it down the 1/4 twice before it exploded!

Even if the engine power falls off, that doesnt mean the car isnt accelerating better than it would in the next gear up. For this is the purpose of a transmission! You have to work all the torque multiplication math to decide the best shift point after seeing dyno graph.

Most people aren't thinking that though. They're thinking peak numbers, more is better. Sure at the drag strip shifting after peak power will be better since when you re-engage you'll be higher in the power than if you shifted lower. But on the street or track I don't see it being worth it. That 600rpm and 1/10th a second you gained isn't going to turn your lap times into Michael Schumacher territory.

Besides, I'd have to pull logs and count time in this case which I've never done to truly know. If you're at 300hp peak at 7500rpm, shift and drop to 6000rpm and 270hp, how long does it take to get back to 7500? Then find the time it takes to go from 7500 to 8100 where you're losing power. Is that time greater or less vs the time it takes to go from 6000 to 6600? That should tell you no?

youre not considering the big picture of gearing... +/- 25ft-lb on your dyno graph, is nothing compared to the huge gains of being in a lower gear. Simply downshifting can generate several hundreds of ft lb of torque at the wheels, depending on which 2 gears you are comparing.

Your dyno graph would have to fall down *significantly* to not still be putting more power to the wheels than upshifting, especially in the lower gear ratios

but we arent talking about downshifting. thought we were talking about racing, ie. drag and track so acceleration.

my logs show on my wrx from redline to where the rpms fall after a shift then back up (and where i re-engage is peak power), it takes 2.0 seconds to get there. from peak power down to were the rpms falls after a shift it takes 1.4 seconds. so in this cars case it would seem shifting at peak power is better then going beyond it since the time is faster with every shift. this is only 3rd to 4th so its not like shifting at peak will give me 0.6 seconds in every gear, but you see what im saying.

even if it was 0.6 seconds every gear and the car made power to redline or beyond, the time and rpm isnt worth it to me for the cost of a motor.

I dont know what you are talking about anymore really. I thought we were talking about the purpose of keeping a car in a lower gear longer, spinning the engine faster than peak power. This purpose to it is because torque multiplication in a lower gear will generate greater acceleration than higher power in a higher gear. The greater the difference in gear ratios between the shift, the more reason you have to stay in a lower gear past peak power.

Your saying a slower/higher rpm above peak is better in a lower gear than a lower/faster rpm in a higher gear? I'd have to agree. But add up the times and I think you'd be faster over all in the lower/faster rpm range. It just depends on how slow it is I guess.

But it doesn't matter. Unless you can pull some crazy numbers above the normal redline, plus money spent on the fixing the pump, just leave it.

I am confused at the route of our conversation now... In summary, what I am saying is that a 370z in first gear making 180 torque, will accelerate faster than a 370z in 2nd gear making 250 torque.

180 x 14.01 = 2521
250 x 8.58 = 2145

If you were wondering, 14.01 and 8.58 are the torque multiplication factors of a 370z 6MT in first in second gear with stock final drive.

Do not worry about how fast the RPMs climb, worry about how fast the speed climbs. You are totally overlooking the point of a transmission and final drive.

Rpms=speed though. You can't go faster or slower in 3rd at 4000rpm. That rpm will always equal that same speed unless you change gears, tires etc.

All I'm saying is "if" from 4500-5500 it takes me 1.4 seconds and I shift into 4th vs you going from 5500-6500 and that takes you 2.0 seconds, then you shift into 4th, I'll have been in 4th still in the power 2.0 seconds ahead of you. I get what your saying about gear ratios and the math.

I'll plug the numbers in you gave me and see. But again, if you come out on top shifting later to stay in that gear longer (even though your speed is climbing slow because your powers dying, but I get I could be climbing even slower being in a higher gear), it's still not worth the risk or money dropped. I'll gladly take a back seat to your 1 second faster lap time or 1/10th of a second faster at the strip.

Luckily though this car makes power to 7500rpm and not a lot of dry sumps out there so all we're left with is math vs math :)

:facepalm:

Phunk-
http://4.bp.blogspot.com/-tU4RieFQbI...ZdlW4DiD_c.jpg