mark kibort

No, you are right. no argument either way. as long as you maximize HP over all, you are maximizing potential acceleration capability. there can be no disputing this. In the graphs, you clearly lose acceleration by shifting at 6500rpm, because shifting at 7000rpm,even though the HP and torque are falling off, becuase you dont maximize HP over time. HP-seconds!

So, with the 7000rpm shift, it seems you are maximizing thrust and therefor acceleration by shifting at that point in every gear.

Yep, thats pretty much it.. there can be some variations of this, based on HP curve shape, but generally, this is the best way to maximize acceleration, regardless of what the torque in any gear "feels like" or "seems like" based on a falling HP or torque curve.

because, at any vehicle speed, if you have more HP available at tha speed, you will accelerate at a faster rate. ths goes for comparing acceleration of your own car in different gears, or another same car you are racing against with an entrely different engine. (e.g. the Viper vs GT3 example i often show, both with 450hp, but one with 2x the engine torque of the other, accelerating at the same rate at any spot/speed, on the track!)

Veloce Raptor

Hahahahahahaaaa!

spare tire

The original question is from a "never been tracking a car" type of guy. The correct answer is " You will almost allways experience more acceleration by staying in ther lower gear longer even though the torque curve is past it's peak." This is due to the mechanical advantage of the lower gear. While many exceptions exist, the exceptions are negledgable for a beginner.

mark kibort

Yep, its good for beginners to understand the concepts/theories from the start. the thought of someone thinking peak torque has any relivance in racing makes me cringe. Now, it pays to short shift and sacrafice optimal acceleration while you are learning as you save the equipment. shaving off fractions of seconds while learining the car and track is expensive in the form of equipment wear, so why bother. However, Im only talking about 500 rpm shy of redline. I think its still great practice to shift at the higher RPM to get smooth and precise at it.
When you start racing, its always redline (max rpm possible for your comfort zone), unless you are doing it in a part of the track that would not benefit by it.
anyone that thinks that short shifting before redline, is better because the engine is just making "noise" at that falling part of the torque curve, is providing incorrect information. as you say, almost always, staying in a gear to mechanical limits will maximize HP-seconds and acceleration overall.

Yargk

Simple question, simple answer.

Look up a dyno chart for your car, you want hp vs. rpm (not torque).

Shift at the point such that the hp at that point equals the hp you'd have at the rpm in the next gear. If this doesn't happen before redline, shift at redline.

You can't argue with math.

J richard

...not so fast...

IcemanG17

one huge factor I forgot to mention is how reliable the engine will be near redline....most modern engines are fine...but spending lots of time near redline WILL reduce its service life......especially in engines designed for street cars..... Of course a properly built race engine solves most of these issues.....but generally speaking when you turn UP the rpm....the lifespan on the engine goes down....

I can't remember what the rebuild interval is got 997 Cup cars.....20 hours?

mark kibort

Too bad even after 10 years of this knowledge being available and discussed, there are those that still argue with torque curves, ratios, when the easiest way is to just do what you just stated.



you are touching the redline, not hanging out there! so, for some fickle engines, that redline might want to be set a few hundred rpm lower, but stilll its usually past max HP. what ever you are doing, just do it to maximize HP-seconds!

HJK

50 hours I thought, thats a lot of miles.