MoTeC Global Forum

hello,

is it posible to use launch control without traction control (without speed sensors).

we are driving rallycross division 1 and there is no traction controll allowed.

the car works good, but the starts are terrible.

thx.

regards

Hello,

You could install a push button on the steering wheel or at the top of the handbrake lever, to one of the inputs and configure "dual rpm limit". Its work perfcetly

Hello,

Here is useuful setup
Dig4 function 4
Logic polarity 0
Low RPM limit 4500
RPM rise rate 3000
Ignition retard 17,0

Hello Fetzi,
Can you give me more details on what the car is? Engine, drive train, etc. There are much better ways to do launch control in the current M800 software than Dual RPM Limit (sorry guys). Give me some more details and we can discuss better ways.

hello mark,

engine: ford coswoth 2000ccm, 450 HP, 2,4bar boost (45mm restrictor)
4-wheel drive, quaife 5-speed gearbox and diffs, short gear ratios, vmax 170km/h.
blocked 100% between front and rear.

sensors on the wheels are not allowed. is it possible to write a launch program?
i used the dual rpm limit, but it is very difficult to avoid wheel slip and to produce optimal boost on start line.

thx.
regards

If you put a clutch pedal in you would be able to do something like set off a timer when the clutch is released. The trick with the launch control is that you want to start with too much wheel spin and brin this down quickly to where you need it and then ramp it up as the car accelerates, see diagram. You cannot do this with dual RPM.

You also have problems with 4WD becasue you have no ground speed, you can't use wheel speed sensors by the sounds of it anyway, hence using a timer.

Using the clutch switch you set up a timer (Adjust-General Setup-Timers) and use the timer as an axis on the Launch RPM table. Remember to stop the table axis at the time you want to finish the Launch phase (I assume a second or two), where the table axis stops is where the Launch function stops. You could add a second axis for gear so that the function does not work accidentally around the track.

hi mark,

thank you very much for your information. now it is clear for me. thx.

one last question before i start adjusting:
wouldn't there be the same effect if i adjust the "rpm-rising rate" in the dual rpm parameters?

nice weekend
regards

Not really as good because you are starting from a set RPM Limit and going up from there you cannot have the RPM drop you need as shown in the diagram.

hi,

i tried launch control like mark told me. after some problems with the clutch switch it works well.
but i have following problem:

when i use gear in the y-axis there is a short time before the second gear is detected and the ecu limits to
start rpm (i have no gear shift ignition cut).

so i had the idea to use a second timer on the y-axis which counts when the clutch switch is active and the table for launch rpm only limits when this value is bigger than 2 or 3 seconds.
on the track the clutch is normally pressed not longer than 0.4 seconds but for safety i also want to use gear as a third parameter for launch control (the first gear is only used for launch). is this possible? can i activate a z-axis?

thx.
regards.

Hello

Wire a switch for launch control on/off. Use a hold button on the steering wheel. Then you are 100 % sure that launch control only is in active at start.
You should also try a load cell for quick shift. Much faster gear shift and no wrong gearing.

Regards
Arve Flaat