How to get the best launch?

[Koppel]

Yesterday I practiced some starts and was wondering what is the best way to do this?
According to physics the best acceleration occurs when the wheels are just about to spin.

I revved the engine up to 4500rpm, disengaged the clutch instantaneously and floored the throttle.
On different surfaces the revs that gave me the best launch differed.

So my question is what combination of throttle & clutch I have to use?
Lifting off the clutch more smoothly so I don't have a yank that could produce wheelspin. Not flooring the throttle immediately and wait before the speed matches the revs. ( more throttle could increase wheelspin perhaps? )

EDIT: It was on a RWD car!

[andyhui01]

it depends alot on the car and what sort of layout it has... for example, for AWD Subaru's with 50:50 diff's, get it up till about 4.5k rev and drop the clutch, because its 4wd, it would have minimal wheelspin, it varies alot from cars to cars...

[Hazardous]

Depends a bit on what sort of car you drive as well. Butwhatever the car is like, you shouldn't let the revs drop so low that your start will be slow because of lack of power. I'd use clutch on the start to keep the engine on the high revs without (too much) wheelspin. And I wouldn't get completely off the clutch before the car would be going at reasonable amount of revs without it.

But I'm not the best possible guide here, since I've only done quick starts on ice with spike tyres, which is slightly different than on asphalt.

[Redliner]

That´s hard to answer...each car is different, if it´s AWD, FWD, RWD, the weight, the torque...
I think it´s more a case of "feeling" the car. And I would say that modulating the clutch instead of just releasing it might give a better result. Anyone feel free to correct me.

[patrick10]

Originally Posted by andyhui01

it depends alot on the car and what sort of layout it has... for example, for AWD Subaru's with 50:50 diff's, get it up till about 4.5k rev and drop the clutch, because its 4wd, it would have minimal wheelspin, it varies alot from cars to cars...

you never want to dump the clutch on awd because you will bog like none other, you should slip it a little keeping your revs up.

for rwd if you have sticky tires, dump it but i have a feeling you dont so oyour going to have to slip it a little to prevent wheelspin. just always remember when you are sliping to do it rather fast while still keeping your revs up.

[Z Draci]

Dump the clutch on an AWD car and you will destroy your clutch. Instead, you need to feather the clutch and slip it a bit. Keeping the rpms in the maximum power range is key to keep the car accelerating at its fastest.

Since the powerband is different for all cars, the technique will be different.

[Koppel]

Originally Posted by Z Draci

Dump the clutch on an AWD car and you will destroy your clutch. Instead, you need to feather the clutch and slip it a bit. Keeping the rpms in the maximum power range is key to keep the car accelerating at its fastest.

Since the powerband is different for all cars, the technique will be different.

What if half the power is allready enaugh to spin the wheels? Then there is absolutely no benefit on keeping the revs higher, it would just produce more wheelspin.
The rpm should be without a doubt on the point when the wheels are just about to spin.

(And the best acceleration occurs on the rpm that has max torque not power - tip for allready driving not for the launch)

Put something (car keys for instance) on a piece of paper and pull the paper. The best acceleration of the keys occur when they are just about to slip.

[flyingfridge]

No, rpm should not be on the point where the wheels are about to spin. For the fastest possible launch, you do need to get some wheelspin. Not heaps, not none. it is a balancing act and only practice makes perfect.

[Z Draci]

Originally Posted by Koppel

What if half the power is allready enaugh to spin the wheels? Then there is absolutely no benefit on keeping the revs higher, it would just produce more wheelspin.
The rpm should be without a doubt on the point when the wheels are just about to spin.

(And the best acceleration occurs on the rpm that has max torque not power - tip for allready driving not for the launch)

Put something (car keys for instance) on a piece of paper and pull the paper. The best acceleration of the keys occur when they are just about to slip.

Flyingfridge said it right. You need wheelspin on launch to get the engine rpm to its powerband as quickly as possible. Otherwise, the engine will be bogged down with too much grip.

If the car has too much power (like an F1 car), you need to slip the clutch to control the power output to the tires--whilst keeping the car in its powerband. The launch control program on the Ferrari F430 and BMW M5 also does this automatically. This is why using the launch button on either car too much will lead to premature clutch failure.