Timing and fuel at the starting line?
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
Timing and fuel at the starting line? Hey all.
Now that I have some seat time in the car, I'd like to work on the tune to at least improve the 60ft.
I can get right to 3000 hard on the footbrake. Logs show this is still short of even 100kpa.
Timing there is 20 degrees and AF 14.7 (E85 gas scale)
I go right to 10.8 AFR and 16 deg timing when I mash the gas.
It's taking just about 1.8 seconds to get to 13-14 psi.
It's my understanding that I should have more timing on the brakes. As well as not adding fuel until 4 psi or so?
Just looking for some guidance from those who have successfully done this.
I'm not ready for a converter or a T-brake. I'd like to see how fast I can go w/o. I would consider a two step if that works with the stock ECU.
Ron
Now that I have some seat time in the car, I'd like to work on the tune to at least improve the 60ft.
I can get right to 3000 hard on the footbrake. Logs show this is still short of even 100kpa.
Timing there is 20 degrees and AF 14.7 (E85 gas scale)
I go right to 10.8 AFR and 16 deg timing when I mash the gas.
It's taking just about 1.8 seconds to get to 13-14 psi.
It's my understanding that I should have more timing on the brakes. As well as not adding fuel until 4 psi or so?
Just looking for some guidance from those who have successfully done this.
I'm not ready for a converter or a T-brake. I'd like to see how fast I can go w/o. I would consider a two step if that works with the stock ECU.
Ron
You should have more timing in it and less fuel at WOT out to atleast 5lbs even on a sbe. Is your motor forged? Trying to footbrake only for me was a loosing battle and a waste of passes. It's much more fun leaving off the brake/2step. DO IT!
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
Not forged.
A TB will have to be a winter project. I do my own trans work and I'm slow. I'd miss the rest of the season doing one now. I need gears/spool/axles too.....
A TB will have to be a winter project. I do my own trans work and I'm slow. I'd miss the rest of the season doing one now. I need gears/spool/axles too.....
Last edited by RonSSNova; Jul 9, 2014 at 11:22 AM.
Yeah I am not sure. I have used them on manual cars, but it is kind of a different game. In theory by cutting out cylinders and dumping in fuel it should get some explosions going in the exhaust and get the turbo spooled, but I have not tried it on an automatic.
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Verdad Gallardo It will definitely make more boost faster, but then you have more power and can't hold the tires.
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
Thanks for the PM!
With a 150 shot out of the hole with the rat motor, my car has been on the bumper.
When it wanders off the line now, and the boost hits, the tires aren't planted and don't have a chance. Unless the track is very good.
This ought to be interesting.
With a 150 shot out of the hole with the rat motor, my car has been on the bumper.
When it wanders off the line now, and the boost hits, the tires aren't planted and don't have a chance. Unless the track is very good.
This ought to be interesting.
I don't know, I would think with it cutting cylinders and retarding timing it would not make as much power regardless of what the turbo is doing. But again, I have never tried it on a auto car. We had a Subaru that would spin all 4 wheels coming off the 2 step though, lol.
There's an idea. Hit it with some nitrous out of the hole.
TECH Enthusiast
Joined: Mar 2010
Posts: 519
Likes: 2
Just hooked my msd 2 step back up yesterday. I was a 6 speed and the msd was set to 3500 I could build 10psi in about 3-4 sec with a stock cammed ls1, 3 inch hot pipe, rear mounted 7685 t6 .96 a/r garrett from a bus.
Now with the front mount tc7875 and th400 my 3500 circle d wouldn't let me foot brake past 3k rpm and no boost.
Tested the 2 step out yesterday and I can get to 3k rpm and once the 2-step kicks in I can floor it and the car goes no where. Builds 5lbs in just a few seconds.
Afr on the wideband was showing 12.50s....sure it isn't right since cylinders are being cut on and off repeatedly
Now with the front mount tc7875 and th400 my 3500 circle d wouldn't let me foot brake past 3k rpm and no boost.
Tested the 2 step out yesterday and I can get to 3k rpm and once the 2-step kicks in I can floor it and the car goes no where. Builds 5lbs in just a few seconds.
Afr on the wideband was showing 12.50s....sure it isn't right since cylinders are being cut on and off repeatedly
Just hooked my msd 2 step back up yesterday. I was a 6 speed and the msd was set to 3500 I could build 10psi in about 3-4 sec with a stock cammed ls1, 3 inch hot pipe, rear mounted 7685 t6 .96 a/r garrett from a bus.
Now with the front mount tc7875 and th400 my 3500 circle d wouldn't let me foot brake past 3k rpm and no boost.
Tested the 2 step out yesterday and I can get to 3k rpm and once the 2-step kicks in I can floor it and the car goes no where. Builds 5lbs in just a few seconds.
Afr on the wideband was showing 12.50s....sure it isn't right since cylinders are being cut on and off repeatedly
Now with the front mount tc7875 and th400 my 3500 circle d wouldn't let me foot brake past 3k rpm and no boost.
Tested the 2 step out yesterday and I can get to 3k rpm and once the 2-step kicks in I can floor it and the car goes no where. Builds 5lbs in just a few seconds.
Afr on the wideband was showing 12.50s....sure it isn't right since cylinders are being cut on and off repeatedly
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
That's good to know. 5lbs would get my car moving nicely. And I'd imagine full boost will happen quicker too.
I will check into it!
Ron
I will check into it!
Ron
Last edited by RonSSNova; Jul 10, 2014 at 11:53 AM.
On The Tree
Joined: May 2012
Posts: 175
Likes: 0
20degrees before boost seems kind of low. What's your timing at cruise and at idle? Also i have a t-brake in my car, if I leave with no boost it builds up quickly and spins, if I leave at 5lbs it plants the tire hard and won't spin at all.
Thread Starter
Joined: Aug 2011
Posts: 4,729
Likes: 814
From: Portland, OR
Idles nice at 24 degrees. Cruise is typical 38+.
I think I may have set that pre boost timing low in early tuning when I was seeing some KR in that range. Not sure
I think I may have set that pre boost timing low in early tuning when I was seeing some KR in that range. Not sure
What converter are you using? Sounds like your in the same boat as me. IMO you shouldn’t have to make 13-14psi off the line to 60’ well. My 9.5” PTC doesn’t couple for shyt off the line. I can launch the thing at 24lbs off the brake and dead hook. Only good for mid 1.3x 60’s. Yet we have guys leaving at 3-5psi off the foot brake netting the same 60’s. On a moderate street/strip car like yours I think you need a converter that couples harder on the launch. Then beef up the brake system to hold that boost on the line.
That said theres a few strategies to build boost more quickly. What EMS are you using?
If you have a 2-step with programmable timing control you can pull a ton of timing down low on a switch. From what I see when most retard timing to build boost they don’t pull enough. My AEM 2-step would target -17* resulting in shotgun like explosions coming from my pipes and I could build 25lbs nutty fast. The motor also let go while doing this on the starting line. But to be fair I was using an autozone cam gear and chain on an the old original crank gear with a ton of slop. I hear the 2-steps hammer the crap out of the timing sets.
Here is the more popular method I’ve seen. Probably easier on parts as well. Need to watch in HD to see his data log numbers clearly.
40* to 25psi 13-14AFR. Once the guy releases the brake watch how low the timing goes initially though I’m not sure how to program that in. And 40* at 13-14AFR would make me nervous as hell!
http://www.youtube.com/watch?v=Ur6JFk5Old0#t=21
That said theres a few strategies to build boost more quickly. What EMS are you using?
If you have a 2-step with programmable timing control you can pull a ton of timing down low on a switch. From what I see when most retard timing to build boost they don’t pull enough. My AEM 2-step would target -17* resulting in shotgun like explosions coming from my pipes and I could build 25lbs nutty fast. The motor also let go while doing this on the starting line. But to be fair I was using an autozone cam gear and chain on an the old original crank gear with a ton of slop. I hear the 2-steps hammer the crap out of the timing sets.
Here is the more popular method I’ve seen. Probably easier on parts as well. Need to watch in HD to see his data log numbers clearly.
40* to 25psi 13-14AFR. Once the guy releases the brake watch how low the timing goes initially though I’m not sure how to program that in. And 40* at 13-14AFR would make me nervous as hell!
http://www.youtube.com/watch?v=Ur6JFk5Old0#t=21