Another launch control thread....

[Andy P]

Sorry about this guys but I'm trying to get my car to build boost when stationary. I've read the other threads and had a browse through the wiki without too much luck.

Ok lets start from the beginning...


Launch control max rpm Self explanitory I want a 4000 rpm launch.

Control range Assuming this is the rpm "window" allowed??

Fuel based launch control rpm limit To be honest, I've no idea what number should be in here....

Fuel enrichment I assume this is relitive to the fuel table???

Ignition retard I know this is relitive to ignition table.

Now the question is, what sort of numbers should I be putting in as a starting point???

I've been told I'll need ignition set to about 0deg. As this is relitive, do i have 0 deg at 4000rpm/desired kpa? or idle kpa? 

How much fuel do I need?? I've played about with numbers from 0% to 100% with no luck.

I'm not getting any ignition in the manifold. The rev limit works fine but I'm having trouble getting boost to build. The best I've had is about 130kpa @ 4k.

Any help???

Thanks Andy

[rob@vems.co.uk]

As launch and Anti-lag are two separate things I'm a bit confused as to why they'd be on the same screen there.
What I'd try to do is try and set them up independently - get the Launch working first (which you seem to have done) make a note of what your settings are , then get into the Anti-lag set-up and get that working, and bring the two functions back together...

[Andy P]

It shouldn't really be called antilag on that screen in my opinion because that confuses the subject. Its not antilag as such but its a method of building boost without load (but full throttle). Antilag reduces boost lost with the throttle plate closed. "Real" antilag requires a method of allowing air into the cylinders via another valve (much like IAC but larger) for combustion to take place.

Launch control at full throttle should limit the rpms and at the same time retard ignition and dump more fuel to spool the turbo. This combined with a clutch switch allows full throttle shifting whilst retaining boost (dip clutch with WOT, revs drop to required rpm whilst still creating boost, lift throttle after gearchange and you've got instant boost...)

From another forum...

Originally Posted by Tire Shredder 
what's it like? are you able to get some consistent launches, can you tell you're retaining boost between shifts?

pink is boost. upper yellow is rpm's. notice i didn't keep in the throttle from 1st to 2nd, or 3rd to 4th, but 2nd to 3rd was all in. boost dropped down to 10psi, but normally drops to way below zero (vacuum).

for some reason my TP did slightly dip

http://www.youtube.com/watch?v=dHuUfSPbhko

http://www.youtube.com/watch?v=zY__WTKXgYc&feature=related

http://www.youtube.com/watch?v=WUPoNRCMdAA

Andy

(edited to correct links!!)

[rob@vems.co.uk]

Looking at the code behind the screens
vemsv3.ini shows the fields:
Fuel enrichment relates to launch_enrich
Ignition Retard relates to launch_retard

And correspondingly global.h
launch_enrich;   // launch, fuel enrichment [0.4%]
launch_retard;  // launch, fixed ign. retard [1/4 crankdeg]

What does this mean?  Well I have no idea because I can't see how they're used in the firmware, but I do know that they've got NOTHING to do with the ALS stuff.
  uint8_t als_deact_rpm;      // als,switchoff rpm [100 rpm]
  uint8_t als_deact_time;      // als,switchoff time [sec]
  uint8_t als_deact_egt;      // als,switchoff egt [5 deg celsius]
  uint8_t als_retard;         // als,max ign. retard [1/2 crankdeg]
  uint8_t als_rev_limit;        // Rev limit when ALS active [100 rpm]

Also there seems to be nothing in the ini file that sets:
    uint8_t launch_out_delay;     // time delay for this function after' release of launch control button (100mS scale, 0-25.5 seconds)
    uint8_t launch_out_pwmlow;    // start pwm ramp from this setting (% dutycycle) can share config byte with launch_out_pwmhigh if we are out of space
    uint8_t launch_out_pwmhigh;   // end pwm ramp at this setting (% dutycycle) can share config byte with launch_out_pwmhigh if we are out of space
    uint8_t launch_out_pwmramp;   // time for pwm duty to ramp between pwmlow and pwmhigh (100mS scale)
    uint8_t launch_out_ontime; 

[Andy P]

Hmmn... strange. I agree there should be no relation because they're two seperate things. Inputting different values does make a difference though - If I put "0" in for retardation it makes no difference to the spark angle on the launch limiter when other values alter angle accordingly.

If I stick more fuel in I can smell the unburt fuel.

I think its just a case of me playing some more until i get the timimg right for that big bang....

Will update as soon as I'm spitting flames....

Andy

[Denmark]

Is that on the video setup using a clutch switch, or how do you activate it?

there is nice flames on the video, but isnt that yours?


/Skassa

[Andy P]

Is that on the video setup using a clutch switch, or how do you activate it?

there is nice flames on the video, but isnt that yours?


/Skassa

Skassa,

Edited the links above because they were all the same!! oops!

The mx6 in the video is not my car - just one i found on youtube to demonstrate what I was after.

Yes, it's activated by a clutch switch. I'll just use a brake light switch mounted on the clutch on an adjustable braket somehow - so I can adjust it depending on the bite of the clutch.

Andy

[lugnuts]

Set your control range down to 25 or 50 RPM. This will make the rev limit more accurate.
You are pulling 30 degrees timing out with the launch. this is usually enough to make a lot of boost. But your launch RPM of 3400-4000 might be too low. What turbo do you have?

Finally, adding fuel is not really necessary to build boost. People only add fuel to keep the EGT down while using the launch control and when rally cars use antilag. Perform your own test using the Launch Control while watching the EGT to see if any added fuel is even necessary.

[Andy P]

Lugnuts,

The turbo is a GT2876R.

The problem is that it dosen't seem to be igniting at all... no pops or bangs.

Andy