00civicman

can someone explain launch control to me

sircrx

Launch control is something you can add to a tunable ECU (Or I think msd makes an add on piece that will do it) that acts almost the same as the rev limiter of your car but much lower so it won't harm the motor.

That way you can just floor the gas pedal and the launch control takes over and won't let it rev past your desired RPM. That way you launch pretty much the same every time.

Ex- If you set your launch control to 4000rpm and you get in your car and the car is not moving (sitting at the starting line) and you get ready to go you just floor the gas. The car will rev to 4000rpm and stop so all you have to worry about is watching the light and letting go of the clutch. As soon as the car starts moving the computer senses it and turns off the launch control and lets you shift at redline or wherever you want.

Hope that helps

Fabrik8

There are different types of launch control, the kind mentioned above is called a 2-Step rev limit, and isn't really technically launch control at all. Launch control works very similar to traction control, which does an ignition retard (or lowers spark energy, or closes a drive-by-wire throttle) to cut engine power in order to fight wheel spin. So basically you plant your right foot and it takes care of controlling the wheelspin for you. This is not usually done on common street cars because there isn't usually any way to feed individual wheelspeed inputs into the ECU to do speed/power feedback. Usually each driven wheel speed is both compared to one or more of the undriven wheels speeds, and there is some feedback involved. There are crude forms though, which are more common and just compare vehicle speed (transmission output speed) vs. RPM, and adjust accordingly. This can be done in a lot of the aftermarket tuning software for stock ECUs, along with the 2-Step rev limit. The speed sensor input usually goes into the ECU anyway, so not that hard to do a simple version.

You can think of it this way: Launch control helps you launch effectively, and a 2-step rev limiter helps you launch consistently.

sircrx

^^^^^^ Very true. Yes I did explain the 2spet portion of launch control. Never thought about true launch control since I assumed this would be for a honda setup since that is what most questions are for on this forum.


Thanks for clarifying that for him/me.

Fabrik8

You can do launch control on a Honda, it just takes some better than average tuning software.. Launch control PID algorithms aren't very easy to add into stock ECU code..
Launch control and traction control both make you realize that the more you know about them, the more you realize the insane complexity involved in making them work well.