Launch control for Motronic

[prj]

Based on the fact that boost will be similarly low to that of a launch on a stock ECU, IME, you cannot just dump the clutch, even at 5000rpm, you need to bring the clutch up quickly but also allow a little boost to build at the same time, such that the engine does not bog down and you achieve a little chirp of the tyres. This system makes holding the RPM simple but it will still require some finesse on the left foot. To get the wheels to spin, you'll need to be very rough with it for sure!

You are wrong here.
You assume that no boost is built, but there is. It is nothing like playing with the gas, because you are WOT and turbo is spooling up.

I get 0.7 bar boost just pushing down the pedal and holding it with the current implementation.
Your turbo is already spooled up and when you dump the clutch it instantly boosts, there is no bogging down whatsoever.
This is for stock turbo.

A larger turbo will not build as much boost, but as long as fuel cut rate can be adjusted, it's possible to build boost without dumping unburned fuel into the exhaust manifold.

I posted videos, here is a video of my car on dry tarmac. All I do is hold down the gas and dump the clutch. My 1.7 tonne UrS6 Avant easily spins it's wheels and keeps spinning:

http://www.youtube.com/watch?v=SgQPEpS25as&hd=1

[Rusty]

That's not what I said; I said that the boost will be low, not that htere will be no boost. It will be interesting to try this and see how it operates.

[prj]

That's not what I said; I said that the boost will be low, not that htere will be no boost. It will be interesting to try this and see how it operates.

0.7 bar is not low on launch with a K24. Also, there is no way you are going to get this much boost without launching off the revlimiter, which is murder for the drivetrain.
It's enough for wheelspin. I don't think playing with the clutch is a good idea, as you might just burn it and not start at all.

Maybe if you fit drag slicks, the 0.7 bar will not be enough.
I mean, I showed you the video. You can clearly see I get wheelspin.
On a S2, which weighs way less than my S6 the effect will be even more pronounced.
Paul's car spun wheels at only 4000 rpm on dry tarmac and winter tyres. With bone stock ECU, no tuning except the launch control.

[S2central.net]

I'd love to see the drivetrain and tyres that could sustain a launch above 1bar boost on a regular basis. I was impressed with the quick test I had yesterday. Hopefully some gtech data will backup my neck muscles !

[Costash]

Can I sign in for the second kit?

[Rocco]

Dmitri, with bigger turbos like k24 7200 or k26/27 ,how many boost will produce in the launch control??

[prj]

Dmitri, with bigger turbos like k24 7200 or k26/27 ,how many boost will produce in the launch control??

It will be less. Need to try.

[Rocco]

It will be less. Need to try.

ok try with mine

[A1quattro]

my rally car is only 1166kg so launch control should be pretty impessive ftom inside the car. even if it only saves me 1 second off the start line ,most rallys have 8-10 stages [the blackpool rally has25+] so 8 secnds + could get me that extra place at the finish ramp on the last event 3wks ago we were 7th o/a out of 91 cars only 6 seconds from being 6th ,the 6 cars in front were 1 wrc subaru,1 wrc focus,1 evo 9, 2 darrian [kit cars700kg ],and a bloody 1400cc/190bhp nova[700kg]we were in beating , 15 cars in our class, but i went off on stage 3 sorry its off topic [just fying the audi flag]

[mouse]

Yes - this isn't just a case of wiring up any old pot to an unused ECU pin... There are some internal mods required on the ECU to make the unused input active and to get the voltage levels correctly balanced for operation across the revs - with boundaries that we have in the code to behave correctly if the pot is unplugged and when a clutch switch is detected in the future.

I intend to offer the Variable Launch Control (VLC) as an upgrade to any 20VT ECU that includes the internal mods with a nicely connectorised loom that can be user installed for the pot location.... this will also be plug and play forwards compatible for features with the clutch switch to come in the future....

So if Launch Control is installed would the ECU have to be sent in to add FFS in the future? Or just chips?

[prj]

Just chips and a switch under the clutch.
Or to be more correct - one chip.

[Rusty]

How would the FFS kit affect throttle blipping during downshift, either during heel and toe or just rev matching? Would the clutch pedal need to be fully home to enable the engine to rev?

[prj]

FFS would only be enabled if your TPS is over 90 or 95%.
I don't think you press the throttle that much when blipping.

[Rusty]

OK, cheers

[Ruffiano]

It will be less. Need to try.

you should try with a k24 7400...