Tuning for launch control...

[kc95sc400]

So I am still attempting to break the 12 second barrier with my car LOL. For anyone following along I've managed a best of 12.04.

I have run a few times (1/8 mile) since putting in an Adaptronic ECU but have had a few issues, I think I finally have it all sorted out and would like to give launch control a try since launch consistency is usually my biggest issue.

Here is how I plan to set it up, please if anyone has any input, let me know.

I plan to cut fuel to control the RPM. Will attempt to have it set for 3000rpm since this is my stall speed. The problem I will have is that at 3000rpm the brakes will not hold the power and the car will surge forward everytime the power is on. So in an attempt to hold the RPM and reduce the power a little I was thinking about using an alternate timing map when launch control is activated. I was thinking about using 15 degrees across this alternate map then when the car moves and launch control is disabled by speed it will revert to my normal and far more advanced ignition map.

I have already set this up in the software and it appears that it will work I'm just not sure on the safety of it all.

Again, any input welcome!

Thanks,

KC

 

[stevechumo]

Good luck, Khris! Seem like you always progress with something.

 

[kc95sc400]

Good luck, Khris! Seem like you always progress with something.

Thanks Steve. I'm still waiting for you to run your car!

Although I'd like to be the one to break into the 11's, LOL.

KC

 

[stevieg]

I plan on doing the same thing in my megasquirt but it's not a good idea to fuel cut, as it will cause a lean condition. The way the megasquirt does is spark cut and timing retard to spool the turbo

Steve

 

[kc95sc400]

I plan on doing the same thing in my megasquirt but it's not a good idea to fuel cut, as it will cause a lean condition. The way the megasquirt does is spark cut and timing retard to spool the turbo

Steve

You can't run lean if there is no combustion event and there won't be a combustion event if no fuel is injected.

I think it is more dangerous to spray fuel into a combustion chamber that is heating up due to retarded timing / cut ignition / high EGT's than sparking in a chamber that has no fuel in it. No fuel means no boom. Spray fuel into an overheated chamber could mean unplanned boom.

I'm hardly an expert but I think both methods have there use if done correctly.

KC

 

[kc95sc400]

Also (sorry to double post) from what i've seen, fuel cut is a very safe way to cut power.

When I still had the factory ECU / Maftpro combo and before I had my transmission controller I used to hit the rev limit fuel cut all the time on WOT 1st to 2nd gear shifts.

I could probably find a few logs of my car at 6500rpm 180kpa of boost and 20 to 1 AFR. Nothing bad ever happened.

KC

 

[XR8tt]

If its an auto / turbo you advance timing to get motor up on converter.. then use 2 step [lower rev limiter] to hold it there...
If turbo ?? The excess fuel is burnt in the turbine.. This spools turbo very quick..
It helps to have a trans brake .. But I assume you haven't got one ??

On manual the timing is generally retarded on 2 step while fuel is dumped to spool turbo.. Don't hold too long at this .. It's hard on turbo..
If you see the quick cars on YouTube.. You'll notice flames coming out exhaust .. Usually blue as they are running alcohol or E85 these days..

A 2 step could be in ECU as part of launch control [another name for it]
Or they are in ignition box's such as MSD2 etc...
You have to experiment somewhat as all combo's are different...
On a s/c .. Just the 2 step is used at launch RPM..
Due to being almost NO load on engine there's no effect on engine durability ...