acceleration near redline in 996's

After tracking my '02 996 C2 a few times now, I've noticed something that atleast seems interesting to me... It seems that in 2nd gear, I accelerate the fastest when I basically take it all the way to (just before) redline before upshifting to 3rd. However, when going from 3rd to 4th, it seems that acceleration is better when I short shift a bit, shifting at like 6200-6400, rather than 7200. Any experiences that you guys have that confirms or contradicts this? If this "feeling" is reality, what could explain it?

Mathematically speaking, torque defines accelaration which itself defines speed... Therefore you must change to the next gear at the maximum ratio of Torque/rpm of the engine's envelope.. Meaning: if the maximum torque of the engine happens to be at 6,000rpm then you must shift to the next gear in a way that the rpm will read 6,000... therefore you are at your maximum torque, resulting in max instantenous accelaration, resulting in maximum speed increase... ..go figure! Waz *I'm back!*

Ditto with Waz. The Torque band of M96 engine is between 3750-6000. (page 255, 03 Manual) 7200 rpm in 2nd = 5000 rpm in 3rd, (page 257, 03 Manual) 7200 rpm in 3rd = 5750 rpm in 4th, Torque is rapidly running down, 6200 rpm in 3rd = 5000 rpm in 4th, about the same you did from 2nd to 3rd. hope this helps. Cheers!

Yes, but it is important to understand that engine power, not engine torque drives acceleration. People often confuse this, because they think in terms of a=F/m. This is of course correct, but the catch is that the F here is the force (or associated torque) at the wheels, not at the crank. This is what engineers call the TRACTIVE POWER. Therefore: Engine TORQUE defines acceleration in a given GEAR, engine POWER defines acceleration at a given SPEED. Obviously, for best acceleration, we need to make sure that the tractive power at the wheels is as high as possible at all times. The way to find out is to draw a chart called a tractive power chart. Basically, it contains the speed on the x-axis and the tractive power on the y-axis. As the tractive power depends on the gear, there will be 6 graphs for a six speed gear box. This chart is what we use when we define the gear ratios in gearbox, basically we want to make sure that once you have reached maximum revs in one gear that there is comparable tractive power in the next gear. You can also use this chart to find out the best point at which to change into the next gear: If at a given speed the tractive power in a gear is lower than it would be in the next gear up, it's time to upshift. I've calculated a tractive power chart for the M96/01 and you can see that in 1 gear it makes sense to go all the way to the red line, in second to about 7000, and then down to about 6500 in fifth. I know this is a bit hard to explain without showing the actual chart, but if someone has got some webspace to upload the chart, I'd send it per email. Cheers, Uwe