Timing and fuel at the starting line?
Even in an automatic without a trans brake a 2 step will help spool the turbo because it will allow you to got WOT without pushing thru your brakes on the line. When you are footbraking it up until your max rpm before pushing begins your T/B obviously isn't at 100% tps. So you would set the 2 step to allow a WOT launch from just below whatever RPM the car starts to push through the brakes. The engine load from the 2 step and being at WOT will spool the turbo much faster than footbraking it at say 70% throttle.
In short if your car starts to push at 3200 rpms then set the 2 step to 3000 hold it WOT and let off the brakes and 2 step simultaneously on green.
I have done this on my current car with good luck and I'm even launching at an RPM well below where my turbo really starts to spool. But it really makes a big difference by being WOT when releasing the brake vs applying only enough throttle to not roll out of the beam
In short if your car starts to push at 3200 rpms then set the 2 step to 3000 hold it WOT and let off the brakes and 2 step simultaneously on green.
I have done this on my current car with good luck and I'm even launching at an RPM well below where my turbo really starts to spool. But it really makes a big difference by being WOT when releasing the brake vs applying only enough throttle to not roll out of the beam
Thread Starter
Joined: Aug 2011
Posts: 4,732
Likes: 815
From: Portland, OR
My converter is a 9" ATI. Spec'd for my 496 on a small shot.
EMS is the factory PCM. I'm the tuner.
The converter is actually quite tight. There isn't much torque in the 5.3 out of boost compared to the rat.
My 3600 Yank in my vette is much looser by comparison.
It's not getting a converter. Unless I get a job. So I have to work with what I have for now.
EMS is the factory PCM. I'm the tuner.
The converter is actually quite tight. There isn't much torque in the 5.3 out of boost compared to the rat.
My 3600 Yank in my vette is much looser by comparison.
It's not getting a converter. Unless I get a job. So I have to work with what I have for now.
Even in an automatic without a trans brake a 2 step will help spool the turbo because it will allow you to got WOT without pushing thru your brakes on the line. When you are footbraking it up until your max rpm before pushing begins your T/B obviously isn't at 100% tps. So you would set the 2 step to allow a WOT launch from just below whatever RPM the car starts to push through the brakes. The engine load from the 2 step and being at WOT will spool the turbo much faster than footbraking it at say 70% throttle.
In short if your car starts to push at 3200 rpms then set the 2 step to 3000 hold it WOT and let off the brakes and 2 step simultaneously on green.
I have done this on my current car with good luck and I'm even launching at an RPM well below where my turbo really starts to spool. But it really makes a big difference by being WOT when releasing the brake vs applying only enough throttle to not roll out of the beam
In short if your car starts to push at 3200 rpms then set the 2 step to 3000 hold it WOT and let off the brakes and 2 step simultaneously on green.
I have done this on my current car with good luck and I'm even launching at an RPM well below where my turbo really starts to spool. But it really makes a big difference by being WOT when releasing the brake vs applying only enough throttle to not roll out of the beam
9 Second Club
Joined: Dec 2010
Posts: 147
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From: Michigan
Add more timing. I'm at 35 degrees and I believe 13.5 AFR but I just leaned it out some more. I was only building 3 psi on the footbrake with a 1.32 AR 96mm on a 6.0. I hooked up my 2 step and it helped bump boost up even more but for whatever reason the damn thing quit working on me or else I'd have a better answer for you.
Whats your 60'?
Whats your 60'?
Add more timing. I'm at 35 degrees and I believe 13.5 AFR but I just leaned it out some more. I was only building 3 psi on the footbrake with a 1.32 AR 96mm on a 6.0. I hooked up my 2 step and it helped bump boost up even more but for whatever reason the damn thing quit working on me or else I'd have a better answer for you.
Whats your 60'?
Whats your 60'?
So far the best 60' I've ever gotten with this car is 1.6s on the footbrake. I would LOVE to see some 1.4s without having to monkey around with my converter again. I can hold the car on the footbrake right around 3k but I'm still not building boost. I assume it's because the throttle blade isn't opened enough. Anything more than about 3000-3200 the car begins to push. So if I can figure out the best way to set my tune up while on the 2 step that would be great!!
I’ve yet to see an LS setup car use this method and it plain works. Was able to launch at 30+lbs with this method on a import build.
Last edited by Forcefed86; Jul 11, 2014 at 03:04 PM.
Beef up your brakes. Hard aftermarket brake pads do a poor job of holding a wheel static, esp with little to no heat in them. Get some soft cheap pads on the rear, extend your brake pedal and plumb an electric vacuum pump on your brake booster. Put some serious foot pressure on that pedal as well. Should hold some serious power this way without a T-brake. (drum brakes work even better than discs)
I’ve yet to see an LS setup car use this method and it plain works. Was able to launch at 30+lbs with this method on a import build.
I’ve yet to see an LS setup car use this method and it plain works. Was able to launch at 30+lbs with this method on a import build.
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Verdad Gallardo Thread Starter
Joined: Aug 2011
Posts: 4,732
Likes: 815
From: Portland, OR
Turbo Buick guys went even further by putting two long shoes on each side, changing to a bigger wheel cylinder and reinforcing the backing plates.
As well as biasing the braking to the rear wheels.
Have to be careful though, because it sort of takes the front brakes out of the equation when stopping after a pass.
I put soft semi metallic rear shoes on, biased my brakes to the rear. It is interesting slowing after a run.....
I also give the drums and shoes a scuff and adj the shoes throughout the season.
As well as biasing the braking to the rear wheels.
Have to be careful though, because it sort of takes the front brakes out of the equation when stopping after a pass.
I put soft semi metallic rear shoes on, biased my brakes to the rear. It is interesting slowing after a run.....
I also give the drums and shoes a scuff and adj the shoes throughout the season.
Not to steal from Ron...
But, is simply installing a rev limit/2 step a sure-fire way to build boost? Be easier to do that than redo the brake system.
The Holley efi I'm running has 3 rev limiters so I already have something to work with.
But, is simply installing a rev limit/2 step a sure-fire way to build boost? Be easier to do that than redo the brake system.
The Holley efi I'm running has 3 rev limiters so I already have something to work with.
The Holley allows fuel, spark, fuel/spark cut-offs during the rev limits. Theres also a "soft" function? Anybody care to suggest which setting would give best results? Of course I'll try all but looking for the Cliffs Notes here.
so with an auto and no trans brake if i put a two step in and tune it just below my foot brake push through rpm but retard the timing like i would on a manual it will build boost and allow full throttle launch. i have a 6l80 so no trans brake available and have tried foot braking but i always push through the brakes far before i start building boost so my best 60 foot has been a 1.80 with my 2012 camaro. im just suprised because everyone i know told me unless i had a trans brake a two step was a waste of time. if this works i might actually quit being embarassed about my car quarter mile times.
9 Second Club
Joined: Dec 2010
Posts: 147
Likes: 0
From: Michigan
Theres been discussion on other boards that with an auto trans you would add timing and lean it out on the 2 step. I'm not 100% sure as I havent had enough testing time myself but I was just putting it out there. Hopefully someone else can chime in.
Thread Starter
Joined: Aug 2011
Posts: 4,732
Likes: 815
From: Portland, OR
Sarg,
Perhaps it has to with the fact that a manual puts no load on the engine? Trying to wrap my head around it as well.
I'll mess with mine after the current heat wave subsides. F'n around with the car in triple digit heat is just not my idea if fun.
Car doesn't like it either I'm sure.
Perhaps it has to with the fact that a manual puts no load on the engine? Trying to wrap my head around it as well.
I'll mess with mine after the current heat wave subsides. F'n around with the car in triple digit heat is just not my idea if fun.
Car doesn't like it either I'm sure.
Last edited by RonSSNova; Jul 12, 2014 at 02:05 AM.
You can do that with an auto as well, it's known as "anti-lag". I didn't want to do that since I've read that it is much harder on parts
Well, that is not a true anti-lag, haha. That usually involves air injection and such and you are right is pretty nasty on the turbine if held for too long. I got to play around with it on a Subaru I tuned. Kind of scary the first time you do it! But I think just pulling a little timing and fattening it up could work too provided you are able to lean it out fast enough when the button is released. On the Subaru I tuned it was just one or two cells on the ignition map and the VE map that were not really hit in normal driving so it worked out pretty well.