Another thread seeking advice and tips on learning how to shift got me wondering what the various theories were of board members on performance shifting. Some suggest shifting at redline, while other approaches tend to advocate trying to shift at the point when HP after peak is approximately equal to HP before peak (i.e., after shift). I tend to subscribe to the second theory, but you have to know the cars performance curve and even then, it may not be possible depending on the shape of the curve.

What are everyone else's thoughts and approaches?

 

Forget horsepower peak or other mumbo-jumbo. You should shift slightly after you feel the car's forward progress is lagging. Not before and not much after.

 

DrPJM, the car's forward progress starts lagging as soon as you pass peak HP, so you routinely shift at 6K RPM, give or take? The "mumbo jumbo" as you call it is pretty important and while you might drive by feel, there are technically optimal shift points. Ask any automotive test driver or professional racer.

As for the engine being easier to power in lower gear, that is absolutely true, but it doesn't mean you should stay in a lower gear just for that reason. Ideally, you are trying to stay in the range where the car is accelerating at its fastest, which may be in a higher gear, yet lower engine speed.

 

MrElussive, the G's redline is at 6600 rpm, and the rev limiter is at 7000. For 05's, the redline is 7000 but I don't know where the limiter is. Anyone want to test their 05 out and report back?

 

Its a bell curve...no point in going 100-200 into redline. At redline should be absolute dead point of when to shift or else your just loosing power.

 

not on all cars, on my old '00 celica GTS it made all the power up top and had a redline of 7800 but cut off was at 8243 (SAFC gave exact number) and it was beneficial for our cars to get to as close as possible to that cut off point without hitting it. Dyno's showed for the GTS that power increased all the way up, but Im not sure about the g35

 

Shift early on the g35c when the torque starts to lag. No use reving up to
redline. Even Gan-san (Bestmotoring) said so regarding this motor.

 

isnt it better to shift less than to shift more... isnt it better to end a race .. say near redline in third... than to be 5-6k in 4th?

 

from my drag racing experiences being it was in hondas, usually the best point to shift was about 800 rpms past peek.

Now the motor and tranny may be much different on the G compared to what I'm used to driving, but you want to make sure that your hp point when you start the new gear is not lower then where you were at on the previous gear too.

 

You don't necessarily wanna shift at the peak RPM. The point is putting yourself in the optimal RPM range right after you have shifted into the next gear. For example with a Honda you wanna stay in the V-tec range (above 5900RPM?) and with a BMW you wanna stay in the VANOS range (above 3500rpm) as soon as you get into the next gear.

 

Uther: Yes, there are technically optimal shift points. But is it really necessary to do so in the streets when you can easily do it by feel? You could dyno your car at several gears and then extrapolate to find those precious shift points OR you could do it by feel. I thought it would be easier my way.