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RPM=best performance

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according to alot of dyno charts I have seen for the early model NSX's, they start to lose hP after about 7200 RPM. so would that be the best place to shift or would going all the way to redline be better for 1/4 mile times? why?
 

sjs

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Having measured and charted actual acceleration G's numerous times, I can say definitively that with a stock 5-speed you are far better off holding it to the rev limit in each gear. The loss in acceleration due to the next taller gear ratio is much greater than the loss in acceleration as the HP falls off.

The difference may be less with short gears and/or closer ratios and/or 6-speed, but I have no doubt that holding to the rev limit is still fastest.
 
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sjs is right.

A while ago, someone calculated the optimal shift points for maximum acceleration. As I recall, they were at redline for the 1-2 and 2-3 upshifts. For the others, they were short of redline, but so close (7800 or 7900) that for all practical purposes you may as well try to shift at redline there too.
 

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Originally posted by nsxtasy:
sjs is right.

A while ago, someone calculated the optimal shift points for maximum acceleration. As I recall, they were at redline for the 1-2 and 2-3 upshifts. For the others, they were short of redline, but so close (7800 or 7900) that for all practical purposes you may as well try to shift at redline there too.


Trusting direct measurement over calculations (it's always tough to include all factors) I went back and checked my data. The typical drop in acceleration on a stock '93 was as follows:

1-2 ____ -34%
2-3 ____ -21%
3-4 _____ -7%
4-5 ____ -15%

So even the 3-4 shift is significant in terms of percent particularly since you are in the higher gears for much longer than the lower gears, therefore compounding the effective gain/loss.

Woops! Just remembered that the 4-5 shifts were not always at redline, so the average drop for that shift is high.


[This message has been edited by sjs (edited 02 October 2001).]
 
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Originally posted by sjs:
Having measured and charted actual acceleration G's numerous times, I can say definitively that with a stock 5-speed you are far better off holding it to the rev limit in each gear. The loss in acceleration due to the next taller gear ratio is much greater than the loss in acceleration as the HP falls off.

The difference may be less with short gears and/or closer ratios and/or 6-speed, but I have no doubt that holding to the rev limit is still fastest.

ok, I have the short gears and 4.23 R&P in my 92, would it still be the same? I also have I/H/E and use a 16/17 wheel combo, how much does that effect things?
 
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ok, I have the short gears and 4.23 R&P in my 92, would it still be the same?

Yes.

I also have I/H/E and use a 16/17 wheel combo, how much does that effect things?

Not at all.

More drastic mods MAY affect the torque curve enough to change the shifting pattern, depending on the mods; but many mods extend the power at the upper end of the revband, which just reinforces the need to shift at redline.
 
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a humourous response:

Obviously u want to know 1/4 mile times coz you've just seen the movie "The Fast and the Furious" and you wanna streetrace your NSX?

Cool!
wink.gif
let me know where and when! =)

tip: fit your NSX with nitro... no more RPM restrictions then!
smile.gif


------------------
If the Matrix is real, an NSX is just the figment of your imagination. Damn.

[This message has been edited by NeoNSX (edited 02 October 2001).]
 
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