Building Boost on the Trans Brake
What transbrake do you have in the 4l80e? Is it a Jake's D1 or D3? If it's a D1 (I don't know about the D3), Thadd's method works... with the shifter in 2 and the TB button pressed, it FORCES 3rd gear on the transmission. So while footbraking and laying into the throttle, this helps build boost due to the amount of load. Ease off brake as needed until you're into the 2nd beam... move shifter to 1 while holding TB button and this will engage the transbrake.
I leaned it out a little bit more and tried again with negative results. Leaning it out half a point spool time increased again almost back to where I was before. Didn't have a whole lot of time to experiment. Might play around with it some more later this week. Thanks for all the help guys.
Not disagreeing at all… But if adding timing is the way to go these days, why do all antilag setups I see retard the crap out of the timing to build boost on the line?
For example on 3500rpm 2-step on the brake my antilag settings were at -15* to -17* of timing. THe AEM woudl actually cycle timing very quickly between base timing and -17* or so. This would make 24lbs in 2-3seconds. When TB was released it would it would ramp timing back in very quickly. I launched a JY motor a good 20 times this way and did blow it up on the line on the 2 step at the end of the year. So I’m by no means suggesting this to anyone, just throwing it out there.
For example on 3500rpm 2-step on the brake my antilag settings were at -15* to -17* of timing. THe AEM woudl actually cycle timing very quickly between base timing and -17* or so. This would make 24lbs in 2-3seconds. When TB was released it would it would ramp timing back in very quickly. I launched a JY motor a good 20 times this way and did blow it up on the line on the 2 step at the end of the year. So I’m by no means suggesting this to anyone, just throwing it out there.
I then tried adding timing, it would build 7-8psi super quick in 2-3 seconds, but would then flat line.
I couldn't get it to 60' as quickly as I wanted it to with 7-8psi.
I talked to one of the local turbo racers and he recommended leaving the timing advanced while on the footbrake, but pulling timing once I had the 7-8psi and grabbed the trans brake. Pulling 12* from my 26-28 I had at 7-8psi I was able to go from 7-8psi to 11-12psi in 1 second.
So I used a combination of adding timing and pulling timing.
I feel this is the best way to build boost with a turbo car.
On my old pt88 ls2 drag car i ramped my timing on the brake to 25degrees till about 8lbs and shot for a AFR of 12.5. Then at 8lbs i retarded my timing to 8 degrees and added fuel to 10.8 afr. This is was on e85 also if that matters. But the feeling i had was the car felt perky and spooled up quickly to the 8-9lbs then when the timing was pulled and fuel was added it totally changed exhaust pitch to a low grunt with a fast rpm climb (if that makes sense) which normally made it my 4500rpm 2 step. The moment i felt the 2 step i would let off the transbrake and at that time my boost was at 14lbs launching. Then shot for my normal 11.5 afr. This all happpend in about 3 seconds. This was also on a manual boost controller to the top port of the gate and hptuners, nothing fancy. Also when it bumped the 2 step it would blow a good flew flames out the exhaust.
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Verdad Gallardo On my old pt88 ls2 drag car i ramped my timing on the brake to 25degrees till about 8lbs and shot for a AFR of 12.5. Then at 8lbs i retarded my timing to 8 degrees and added fuel to 10.8 afr. This is was on e85 also if that matters. But the feeling i had was the car felt perky and spooled up quickly to the 8-9lbs then when the timing was pulled and fuel was added it totally changed exhaust pitch to a low grunt with a fast rpm climb (if that makes sense) which normally made it my 4500rpm 2 step. The moment i felt the 2 step i would let off the transbrake and at that time my boost was at 14lbs launching. Then shot for my normal 11.5 afr. This all happpend in about 3 seconds. This was also on a manual boost controller to the top port of the gate and hptuners, nothing fancy. Also when it bumped the 2 step it would blow a good flew flames out the exhaust.
If I just retarded timing it felt slow and sluggish.
If I just added timing it felt sluggish, but built boost fast and flat lined. I know that it doesn't make sense to say is felt sluggish but built boost fast, but I noticed that once it flat lined it just sounded like it had laid over.
When I started using the strategy of adding timing then pulling timing it came up really quick in 2-3 seconds as it would before just adding timing, but as soon as I'd grab the trans brake the sound of the entire motor would change. It literally sounded like a jet engine had come to life under my feet and that at any moment it was going to take off roaring out from under me.
It popped and banged like it had never done before also.
FormerVendor
Joined: Jan 2014
Posts: 323
Likes: 3
9 Second Club
Joined: Jun 2013
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T4 PT88 .96 a/r 370 ci. The converter is a little tighter than I expected it to be on the brake. The car drives nice and I don't think I would like it any looser as far as street driving goes, but it only stalls to ~2600 on the trans brake before getting into boost. Just seems low. Still haven't had a chance to do any testing. I'll try to do something with the car today. 
I hope you get it and best of luck Last edited by turbo6man; Jun 5, 2014 at 04:24 PM. Reason: grammer
^^ I would completely agree that it needs to be loosened up. Look at the way that Zbrowns comes up on RPM as soon as it starts to see boost. There may be some room for improvement but don't spend a ton of time working on it if you are not seeing improvement.
On my old pt88 ls2 drag car i ramped my timing on the brake to 25degrees till about 8lbs and shot for a AFR of 12.5. Then at 8lbs i retarded my timing to 8 degrees and added fuel to 10.8 afr. This is was on e85 also if that matters. But the feeling i had was the car felt perky and spooled up quickly to the 8-9lbs then when the timing was pulled and fuel was added it totally changed exhaust pitch to a low grunt with a fast rpm climb (if that makes sense) which normally made it my 4500rpm 2 step. The moment i felt the 2 step i would let off the transbrake and at that time my boost was at 14lbs launching. Then shot for my normal 11.5 afr. This all happpend in about 3 seconds. This was also on a manual boost controller to the top port of the gate and hptuners, nothing fancy. Also when it bumped the 2 step it would blow a good flew flames out the exhaust.
WOW WOW WOW. That stall is low! Maybe others will chime in but I have been running the same PT88 t4 .96 on my 370 for along time now and have tried a couple local convertor company's and have tried over 6 different convertor stalls with that turbo on the same 370" 9.2:1 compression motor. I have a PTC in it now and car runs about the same as yours(9.2@148). I kept driving thru the convertor until the PTC. What I m trying to say is on the brake if it stalled to 3800 it spooled awesome. At at 3500 it was OK. At 3100 BAD!!! I cannot imagine trying to stall that turbo at 2600!!! I tried messing with the tune and some things would help but it is my opinion that that stall is to low for that turbo/motor/compression. I think you should take circle D up on there offer, Im sure they can loosen it and still be quite streetable and not drive thru it with the power you are making. I am no pro but that is my experience with a very similar build and the exact same turbo. The other thing I did was hit it with a 100 wet shot for just a second or two and it spooled very fast always I hope you get it and best of luck
I hope you get it and best of luck
I'll send you a PM and see what we might be able to work out.^^I think he is on to something ^^
I would completely agree that it needs to be loosened up. Look at the way that Zbrowns comes up on RPM as soon as it starts to see boost. There may be some room for improvement but don't spend a ton of time working on it if you are not seeing improvement.
^^ I would completely agree that it needs to be loosened up. Look at the way that Zbrowns comes up on RPM as soon as it starts to see boost. There may be some room for improvement but don't spend a ton of time working on it if you are not seeing improvement.
Thanks everyone else for your input on this thread. Especially Martin (no offense to anyone else)!
FormerVendor
Joined: Apr 2014
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From: Justin, TX
Things that work for me on gas
A/F should be 12.6-12.8 coming up on boost
wrap all the hot pipes before the turbo
make sure you have no leaks between the connections
advance the cam 4 degrees
get a turbo blanket
do a few tests with 45 minutes cool down time, log A/f and timing
add timing until it stops picking up
Its normal to run considerably more timing in this spot of the map to aid spool up
You can retard timing in an auto setup to build boost but you need to do it once your on the 2 step high and the motor is banging hard.
A/F should be 12.6-12.8 coming up on boost
wrap all the hot pipes before the turbo
make sure you have no leaks between the connections
advance the cam 4 degrees
get a turbo blanket
do a few tests with 45 minutes cool down time, log A/f and timing
add timing until it stops picking up
Its normal to run considerably more timing in this spot of the map to aid spool up
You can retard timing in an auto setup to build boost but you need to do it once your on the 2 step high and the motor is banging hard.
Things that work for me on gas
A/F should be 12.6-12.8 coming up on boost
wrap all the hot pipes before the turbo
make sure you have no leaks between the connections
advance the cam 4 degrees
get a turbo blanket
do a few tests with 45 minutes cool down time, log A/f and timing
add timing until it stops picking up
Its normal to run considerably more timing in this spot of the map to aid spool up
You can retard timing in an auto setup to build boost but you need to do it once your on the 2 step high and the motor is banging hard.
A/F should be 12.6-12.8 coming up on boost
wrap all the hot pipes before the turbo
make sure you have no leaks between the connections
advance the cam 4 degrees
get a turbo blanket
do a few tests with 45 minutes cool down time, log A/f and timing
add timing until it stops picking up
Its normal to run considerably more timing in this spot of the map to aid spool up
You can retard timing in an auto setup to build boost but you need to do it once your on the 2 step high and the motor is banging hard.
I've tried pulling timing on my own personal turbo car. It worked. But it took nearly 6-7 seconds to build 7-8psi and my trans fluid was nearly 220 degrees before I even made it down the track.
I then tried adding timing, it would build 7-8psi super quick in 2-3 seconds, but would then flat line.
I couldn't get it to 60' as quickly as I wanted it to with 7-8psi.
I talked to one of the local turbo racers and he recommended leaving the timing advanced while on the footbrake, but pulling timing once I had the 7-8psi and grabbed the trans brake. Pulling 12* from my 26-28 I had at 7-8psi I was able to go from 7-8psi to 11-12psi in 1 second.
So I used a combination of adding timing and pulling timing.
I feel this is the best way to build boost with a turbo car.
I then tried adding timing, it would build 7-8psi super quick in 2-3 seconds, but would then flat line.
I couldn't get it to 60' as quickly as I wanted it to with 7-8psi.
I talked to one of the local turbo racers and he recommended leaving the timing advanced while on the footbrake, but pulling timing once I had the 7-8psi and grabbed the trans brake. Pulling 12* from my 26-28 I had at 7-8psi I was able to go from 7-8psi to 11-12psi in 1 second.
So I used a combination of adding timing and pulling timing.
I feel this is the best way to build boost with a turbo car.
From what I've seen, most don't retard timing enough. This does add more heat, eventually resulting in the desired launch boost. If you retard timing enough to get a good amount of combustion outside the CC, the turbo lights off quickly. (And violently) I'm sure this is horrible on things... but it works very well.
Pink line is the timing. Where it appears to be a large block thats the ECU cycling -17* and back to base timing very quickly. Blue line is boost. You can see by the ramp rate of the blue line it builds fast! Took me less than 3 seconds once the antilag was popping to hit 24.5psi. Took a lazy 8+ seconds to make 12lbs without antilag on the t-brake/2-step.
Last edited by Forcefed86; Jun 9, 2014 at 02:58 PM.
Don't be afraid to throw lots of timing at it on the brake then immediately take it out off brake then back to normal WOT timing quickly.
See below video that is coordinated with the data log. Shows his timing and boost strategy at launch.
See below video that is coordinated with the data log. Shows his timing and boost strategy at launch.