Timing and fuel at the starting line?
Teching In
Joined: Mar 2014
Posts: 8
Likes: 0
From: Chicago area
The whole thing about pulling timing and adding fuel to build boost faster is pretty much a refugee from days past. The controls and knowledge where not as advanced as today.
Unless you are trying to use anti lag, the engine will make more torque= build more boost faster if it is tuned as an na car would be up until you are making a certain level of boost where you obviously need to pull back the timing and add fuel for safety.
Another trick you can use(foot brake cars) is that once you get to your target launch boost or as high as your brakes will hold- Then you pull timing which will decrease torque and keep the car still but the boost will remain, then once you let off the brake the car will jump to a different cell on the map and timing will be restored to what it should be and the car will leave.
All of the above is obviously for fuel injected cars.
Mike Reichen
Unless you are trying to use anti lag, the engine will make more torque= build more boost faster if it is tuned as an na car would be up until you are making a certain level of boost where you obviously need to pull back the timing and add fuel for safety.
Another trick you can use(foot brake cars) is that once you get to your target launch boost or as high as your brakes will hold- Then you pull timing which will decrease torque and keep the car still but the boost will remain, then once you let off the brake the car will jump to a different cell on the map and timing will be restored to what it should be and the car will leave.
All of the above is obviously for fuel injected cars.
Mike Reichen
I guess that makes sense. I mean the 2 step is kind of acting like an anti lag though by dumping fuel into the exhaust (when spark cuts) which is then igniting in the exhaust pipes. This is kind of the same theory that anti-lag uses. They just typically inject additional air into the exhaust to help ignite the fuel. Once I get my new flex plate put on I will have to play around with pulling some timing in those load areas.
One interesting side note, I had my idle messed up and the computer was pulling timing down to like 6* to try to get the motor to idle lower than 1000 rpms. Exhaust was getting cherry red from the high EGTs, but one thing I DID notice was the turbo would spool off idle! I could hear it spooling at like 1200 rpms, lol.
One interesting side note, I had my idle messed up and the computer was pulling timing down to like 6* to try to get the motor to idle lower than 1000 rpms. Exhaust was getting cherry red from the high EGTs, but one thing I DID notice was the turbo would spool off idle! I could hear it spooling at like 1200 rpms, lol.
This thread is confusing. Are you guys running really low timing on the 2 step or high timing. In this thread, someone said he was running -17* and that race car running 7.5 seconds was running 40+* on the two step.
Retarding the timing (if retarded enough) is lighting off the mixture outside the combustion chamber causing explosions in your hotside. Most don't retard timing enough IMO and that just adds heat which will eventually spool a turbo but it's a slower process. This is why some say bring it up initially with lots of timing and lean AFR, then once boost is being made drop timing ad add tons of fuel.
9 Second Club
Joined: Dec 2010
Posts: 147
Likes: 0
From: Michigan
I just got my 2 step hooked back up this morning. I changed the timing to 38 degrees and 14.5 AFR.
E85/6.0/S480 combo with a Th400. I was only able to build about 3.5 PSI using the "Soft" feature with the Holley system. I didnt try just spark or fuel cut.
I'd like to test the "anti lag" way as well. Any recommendations for timing and commanded AFR's?
E85/6.0/S480 combo with a Th400. I was only able to build about 3.5 PSI using the "Soft" feature with the Holley system. I didnt try just spark or fuel cut.
I'd like to test the "anti lag" way as well. Any recommendations for timing and commanded AFR's?
I just got my 2 step hooked back up this morning. I changed the timing to 38 degrees and 14.5 AFR.
E85/6.0/S480 combo with a Th400. I was only able to build about 3.5 PSI using the "Soft" feature with the Holley system. I didnt try just spark or fuel cut.
I'd like to test the "anti lag" way as well. Any recommendations for timing and commanded AFR's?
E85/6.0/S480 combo with a Th400. I was only able to build about 3.5 PSI using the "Soft" feature with the Holley system. I didnt try just spark or fuel cut.
I'd like to test the "anti lag" way as well. Any recommendations for timing and commanded AFR's?
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
Well, mixed but positive success with adding timing on the foot brake.
I tried 33 degrees up from 24. Through 3200 which is the max rpm I can achieve before the brakes give up.
I can only get to 90KPA.
I also ramped this down from 33 to 24 degrees through 5psi, where previously I went straight to 16 degrees.
It does get into boost much quicker. From 0 to 12psi happens a solid .5 sec quicker.
Which leads to tire spin, .5 sec quicker!
Our track sucks so hard I can't believe it......
Time from the hit to 12 psi is now 1 second......prev was 1.6 seconds.
If the track would hold, I might actually see a 60ft time.
Thanks, this is good progress.
Now about those head gaskets........
Ron
I tried 33 degrees up from 24. Through 3200 which is the max rpm I can achieve before the brakes give up.
I can only get to 90KPA.
I also ramped this down from 33 to 24 degrees through 5psi, where previously I went straight to 16 degrees.
It does get into boost much quicker. From 0 to 12psi happens a solid .5 sec quicker.
Which leads to tire spin, .5 sec quicker!
Our track sucks so hard I can't believe it......
Time from the hit to 12 psi is now 1 second......prev was 1.6 seconds.
If the track would hold, I might actually see a 60ft time.
Thanks, this is good progress.
Now about those head gaskets........
Ron
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I wonder if the 2 step/timing retards/anti-lag etc etc just beats the **** out of the engines. Its gotta be like detonation. I just happen to have the hood open while I was experimenting and after I saw how that engine was jumping around I was like "holy ****".
The brake (wheel) or t-brake ideas are starting to look better.
The brake (wheel) or t-brake ideas are starting to look better.
I just wanted to look at your timing table since you made the adjustments. I also wanted to see the PE/BE tables. I like to look...maybe learn something, I understand if you dont want to share.
9 Second Club
Joined: Dec 2010
Posts: 147
Likes: 0
From: Michigan
Just got in from some 2 step testing myself.
3500 rpm step, spark only.
My timing at 3500 is normally 36 degrees. On the foot brake above 100kpa to 125kpa I set timing to 38-40 degrees and target AFR to 14-14.2.
This is on E85 as well, with my 1.32 AR 96mm hotside I was able to build 6.5 psi (145 kpa) on the foot brake.
Previously I had 36 degrees and target of 13.8 AFR which resulted in 125 kpa
3500 rpm step, spark only.
My timing at 3500 is normally 36 degrees. On the foot brake above 100kpa to 125kpa I set timing to 38-40 degrees and target AFR to 14-14.2.
This is on E85 as well, with my 1.32 AR 96mm hotside I was able to build 6.5 psi (145 kpa) on the foot brake.
Previously I had 36 degrees and target of 13.8 AFR which resulted in 125 kpa
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
Hmmm. Started removing things for the head gasket replacement. Saw an area on the bottom of the pass side exh manifold that had been dribbling water from my weld. Like a pinhole I missed. Closer inspection revealed an inch long crack in my weld. Oops!
I'll be fixing that.....
Not sure how much exh leak it takes to mess up boost. But it will help.
I wonder what the drivers side looks like?
I'll be fixing that.....
Not sure how much exh leak it takes to mess up boost. But it will help.
I wonder what the drivers side looks like?
