6kLaunch

I have spent some time trying to effect a good launching technique, finding the right RPM to launch without smoking the tires. I have found that it is very difficult to get the engine to settle at the desired target RPM. It takes me sometimes 5 seconds playing with the throttle to get the tach where I want it, settled on a speciific RPM.

Lets say I wanted to leave at 2200 rpm. I get the car in 1st gear, with clutch depressed and with my right foot, manipulate the throttle to settle on 2200 rpm. What I experience is that the RPM floats around above and below the target and takes too much time to settle. There is not a direct foot to RPM responce thus I end up overshooting and undershooting corrections.

This can be a little embarassing sitting at the tree as the lights sequence to launch and I am still targeting the RPM.

Does this happen to your cars??? Or do I have an electrical problem with the fly by wire throttle? ?

Is there a product availabe where you can electronically dial in an RPM???

6kLaunch

Bump.

Let me try this again. When you are preparing to launch your car, and you want to target the tach at a specific RPM, how long does it take you to get the RPM to settle on the desired RPM?

While preparing for a launch, I find the RPM takes too long to settle down to the targeted RPM before releasing the clutch.

Did you have this experience?

fdao

Yup, same here. I minimize this by staging quickly before the other guy. I then spent the precious remaining time adjusting to the desired RPM. I usually get to the desired RPM by the 3rd yellow, just in time for launching

6kLaunch

Wouldn't it be great if we had a system that you can preset to a desired RPM. Hit the button while staging and the system automatically takes the engine to the preset RPM. Hit the gas at launch, the preset is released as you launch.

Seems like a good mod! I know they use something like this in Pro Stock cars.. There must be something available for us.

ares

iTrader: (2)

eh, never been a problem, but then again Im not that good that I shoot for an exact RPM, ~2000 is good enough, up or down by 100 or so wont hurt, not me anyway, Im just not that precise.

spn350z

Way before ABS, when you changed tires because of flat spots caused by trying to learn stops w/o lockups (and not because of feathering)

You would "listen" to the engine and tried to time the launch as your RPMs were building up

so if you wanted to launch at 2200 RPM, you would time it so that you released the clutch going from 2100 passing thru 2200 rather than coming down from 2250 to 2200 or at a constant 2200.

Some guy, way before my time and who's last name sounds like a cookie, did some work along these lines....something about an objects resitance to change......

That is you want to release the clutch so that RPMs continue to build up as the clutch engages. Then the other number, besides horsepower, starts to help launch the car....

The better your clutch is able to handle the stress, the higher up the torque curve you can launch.... yeah, let us not forget traction

Just an old fr*t having a senior moment....
rrrmm...rrrmmm....rrrrmmm...rrrmm...rrrrmm

fdao

spn350z,

Hahaha, I am glad you brought that piece of info up! I've been experimenting with my launch techniques, and I noticed that if the clutch grabs while on the upswing, the car launches really well and quickly out of the hole.

6kLaunch

Well that normally how I launch, however I am having a hard time getting the RPM to settle first. Try it on your car. Sit there at idle and time yourself how long it takes to settle in at 2000 RPM. It takes too long. Consequently, when you let out the clutch, the RPM could be anywhere on a short light.

spn350z

Again trick is not to have RPM settle but to launch on the up swing. Try difference sequences of short (very short) burst of rev'ing the engine...1600 to 1800, 1700 to 1900 and final burst 1800 thru 2200

It practice, practice ....

See if you can learn the difference in sound between a burst from 1600 to 1800 v 1700 to 1900 (or whatever range you feel comfortable with 1600 to 1900 v 1750 to 2000 etc)

Launch should be in the up tick somewhere near the launch point you have picked (2200). If you are going from 1900 past 2300 and launch at 2150 or 2250 or 2220 etc does't matter as much as the fact that the engine was rev'ing up PAST your launch target of 2200 RPM.

spn350z

Again trick is not to have RPM settle but to launch on the up swing. Try difference sequences of short (very short) burst of rev'ing the engine...1600 to 1800, 1700 to 1900 and final burst 1800 thru 2200

It practice, practice ....

See if you can learn the difference in sound between a burst from 1600 to 1800 v 1700 to 1900 (or whatever range you feel comfortable with 1600 to 1900 v 1750 to 2000 etc)

Launch should be in the up tick somewhere near the launch point you have picked (2200). If you are going from 1900 past 2300 and launch at 2150 or 2250 or 2220 etc does't matter as much as the fact that the engine was rev'ing up PAST your launch target of 2200 RPM.