WTF! Still no boost of the line!
WTF! Still no boost of the line! Ok, I finally finished installing my Jakes Performance built 4L80E with Jakes transbrake. The Trans is working perfectly, the brake is working perfectly, the convertor is a multi disk Circle D 258mm stalling as advertised. I figured the transbrake would help me build boost. I was wrong. It holds perfectly, and maybe, maybe the car is building 1psi or a little less boost. I need it to build between 5-10psi. I guess the rear mounted GT-88 is not going to work. It makes all the boost I need once I roll out, but it takes about 150 feet before it comes up. The 408 is a dog off the line (No boost), it launched like a stock 346. I have changed cams, I took the GMPP carb style intake off thinking the elbow was the problem and installed a stock LS3 intake, I double checked the cam timing on the old cam and the new one. I have played with the fueling and timing, but nothing seams to make a difference. I do not know what the problem is. I have checked for leaks on the exhaust and intake side. The only thing I can think of is the LS3 Headed 408 is just not making the power it should NA. It was supposed to make 550 to 600hp on its own, but I think its lucky to be making 400hp. I can try a two step for the boost, and I plan to scrap the rear mount setup and move everything up front after Elk season is over. But still, this thing should leave hard even without the boost off the line. WTF! Any help will be greatly excepted.
Its stalling to 2600 or 2700 right now. I did not play with the tune with the 4L80 yet. So it is still set up for the 4L60 with the 4400 stall. It started raining. I will look at putting alot more timing in it down low, and I need to watch the WB and see were the fuel is down there. I know it is not tuned to be loaded at that low rpm because I the tuning was done with the larger stall. Maybe that will help. I guess the next thing to try would be a 2 step.
Its stalling to 2600 or 2700 right now. I did not play with the tune with the 4L80 yet. So it is still set up for the 4L60 with the 4400 stall. It started raining. I will look at putting alot more timing in it down low, and I need to watch the WB and see were the fuel is down there. I know it is not tuned to be loaded at that low rpm because I the tuning was done with the larger stall. Maybe that will help. I guess the next thing to try would be a 2 step.
Ok, I finally finished installing my Jakes Performance built 4L80E with Jakes transbrake. The Trans is working perfectly, the brake is working perfectly, the convertor is a multi disk Circle D 258mm stalling as advertised. I figured the transbrake would help me build boost. I was wrong. It holds perfectly, and maybe, maybe the car is building 1psi or a little less boost. I need it to build between 5-10psi.
I guess the rear mounted GT-88 is not going to work. It makes all the boost I need once I roll out, but it takes about 150 feet before it comes up. The 408 is a dog off the line (No boost), it launched like a stock 346. I have changed cams, I took the GMPP carb style intake off thinking the elbow was the problem and installed a stock LS3 intake, I double checked the cam timing on the old cam and the new one. I have played with the fueling and timing, but nothing seams to make a difference. I do not know what the problem is.
I have checked for leaks on the exhaust and intake side. The only thing I can think of is the LS3 Headed 408 is just not making the power it should NA. It was supposed to make 550 to 600hp on its own, but I think its lucky to be making 400hp. I can try a two step for the boost, and I plan to scrap the rear mount setup and move everything up front after Elk season is over. But still, this thing should leave hard even without the boost off the line. WTF! Any help will be greatly excepted.
I guess the rear mounted GT-88 is not going to work. It makes all the boost I need once I roll out, but it takes about 150 feet before it comes up. The 408 is a dog off the line (No boost), it launched like a stock 346. I have changed cams, I took the GMPP carb style intake off thinking the elbow was the problem and installed a stock LS3 intake, I double checked the cam timing on the old cam and the new one. I have played with the fueling and timing, but nothing seams to make a difference. I do not know what the problem is.
I have checked for leaks on the exhaust and intake side. The only thing I can think of is the LS3 Headed 408 is just not making the power it should NA. It was supposed to make 550 to 600hp on its own, but I think its lucky to be making 400hp. I can try a two step for the boost, and I plan to scrap the rear mount setup and move everything up front after Elk season is over. But still, this thing should leave hard even without the boost off the line. WTF! Any help will be greatly excepted.
2) What are your cam specs
3) You need to move your turbo up front, there is a reason why almost every rear mount turbo car burns up the transmission
4) You need to get a 2/3 step
5) How much static compression does the engine have?
6) Do you have an adjustable timing set?
7) How much timing are you running when your trying to get the motor up on boost?
8) What air fuel ratio are you running when your staging the car?
9) What RPM does the car see in the stage beams, are you WOT?
10) What ECU are you running?
11) What turbine housing are you using, header size and crossover size?
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Its stalling to 2600 or 2700 right now. I did not play with the tune with the 4L80 yet. So it is still set up for the 4L60 with the 4400 stall. It started raining. I will look at putting alot more timing in it down low, and I need to watch the WB and see were the fuel is down there. I know it is not tuned to be loaded at that low rpm because I the tuning was done with the larger stall. Maybe that will help. I guess the next thing to try would be a 2 step.
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Yeah sounds like a rear mount thing and you have big single turbo also. As said you might need to stall to more like 4000 to really build some boost .
I can build boost no problem to 7 or so thats where my gate spring is and no boost controller controlling yet just monitoring.
I have 408. Its super powerful down low. My cam is gt7, my gears are 3.54 , my heads are afr 225. My compression is 9.5 . My stall is 3400 pro yank extreme made for turbos.
My intake is fast 90 with 90 tb. I have zero complaints for down low off boost power.
My turbos are front mount and bet they full spool at 3000. I am expecting the lg turbos when install them to spool 200 to 300 higher maybe.
I have no experience with rear mounts though so what was said in above posts is likely good advice. But for sure a two step should help big time.It builds good boost in all my turbo cars both talons and my 99TT.
Anitlag is also used in stick cars to good effect. And as was said a 50 or 75 shot of nitrous can usually do really good things too.
I can build boost no problem to 7 or so thats where my gate spring is and no boost controller controlling yet just monitoring.
I have 408. Its super powerful down low. My cam is gt7, my gears are 3.54 , my heads are afr 225. My compression is 9.5 . My stall is 3400 pro yank extreme made for turbos.
My intake is fast 90 with 90 tb. I have zero complaints for down low off boost power.
My turbos are front mount and bet they full spool at 3000. I am expecting the lg turbos when install them to spool 200 to 300 higher maybe.
I have no experience with rear mounts though so what was said in above posts is likely good advice. But for sure a two step should help big time.It builds good boost in all my turbo cars both talons and my 99TT.
Anitlag is also used in stick cars to good effect. And as was said a 50 or 75 shot of nitrous can usually do really good things too.
well... So this one Time at band Camp There was this Guy... He had a 408 in a truck with a 80E transmission ... He used every type of Converter known to man to Spool on his Rear Mounted Truck...Since he Started with a S85,S88 and PT94mm G Trim turbos and now 101+mm turbo... I have sent u my phone number a few PMs and made post in your Threads with offers to help and you have allways sorta Brushed me off as some guy with a Truck 
.... So once again Can i offer to help you yet AGAIN ??? FIRST OF ALL ... Fix the tune... with the wrong OS it could be Starting off in 2nd gear........
.... So once again Can i offer to help you yet AGAIN ??? FIRST OF ALL ... Fix the tune... with the wrong OS it could be Starting off in 2nd gear........ 1) What is your cranking compression
2) What are your cam specs
3) You need to move your turbo up front, there is a reason why almost every rear mount turbo car burns up the transmission
4) You need to get a 2/3 step
5) How much static compression does the engine have?
6) Do you have an adjustable timing set?
7) How much timing are you running when your trying to get the motor up on boost?
8) What air fuel ratio are you running when your staging the car?
9) What RPM does the car see in the stage beams, are you WOT?
10) What ECU are you running?
11) What turbine housing are you using, header size and crossover size?
2) What are your cam specs
3) You need to move your turbo up front, there is a reason why almost every rear mount turbo car burns up the transmission
4) You need to get a 2/3 step
5) How much static compression does the engine have?
6) Do you have an adjustable timing set?
7) How much timing are you running when your trying to get the motor up on boost?
8) What air fuel ratio are you running when your staging the car?
9) What RPM does the car see in the stage beams, are you WOT?
10) What ECU are you running?
11) What turbine housing are you using, header size and crossover size?
1)Cranking compression is 155 at my altitude.
2)VTC-3 23X/23X 116 +6 installed to ICL 105
3)I am tired of the rear mount thing, there is alot I do not like about it, not just the boost issues. After Elk season (I have to get alot of stuff ready for that) I do plan on moving it up front.
4)I am going to order one this week.
5)408 with 70cc heads, Ross pistons with -12 reverse domes, should be 10.25:1
6)Yes, Cloyes, cam is set to 105 ICL at Shawns (VS) advise
7)I just finished installing the 4L80 with Tbrake today. I will check here in a little and ad some timing to see what that does.
8)I think I will shoot for 13:1 off boost and set it up to drop to 11.8-12:1 under boost.
9)WOT yes (now with the tbrake), it pulls up to 2700ish, convertor is tighter then we wanted on the tbrake (or the engine is week)
10)Stock 2002 F-body PCM, tuning with HP Tuners
11)I pulled the 1.08 T-6 housing off the GT-88 and installed a Precision Turbo .9? T-4, the smallest housing I could get for it. Exhaust is stock manifolds going into a 2.5" SLP "Y" pipe, then 3" mandrel bent piping to the turbo, 4" mandrel out of the turbo straight out the back. All the exhaust is heat wrapped from the manifolds to the turbo.
Off of the foot brake it takes about half a city block and the boost comes up to my setpoint. She pulls like a beast under 12-13 psi. I have been having this crappy lag issue the entire time. I pulled the 4L60 and went to the 4L80 because I knew I would pop the built 4L60. I went with the transbrake to help the launch. Before I installed the turbo, the 408 ran very week, it only kut a best of 12.70's at 115 NA at 3915 feet elevation, and if memory serves me, a DA of 7000 feet. I have this nasty feeling the 408 is not right. I can not figure out what it is though. I swapped cams, no gain, tunned it and retunned it, swapped from the GMPP carb intake with a low profile edelbroke elbow to the LS3 intake like Shawn advised, but still no gain. There seams there is soemthing not right with the 408.
So this one Time at band Camp There was this Guy... He had a 408 in a truck with a 80E transmission ... He used every type of Converter known to man to Spool on his Rear Mounted Truck...Since he Started with a S85,S88 and PT94mm G Trim turbos and now 101+mm turbo... I have sent u my phone number a few PMs and made post in your Threads with offers to help and you have allways sorta Brushed me off as some guy with a Truck .... So once again Can i offer to help you yet AGAIN ??? FIRST OF ALL ... Fix the tune... with the wrong OS it could be Starting off in 2nd gear........
.... So once again Can i offer to help you yet AGAIN ??? FIRST OF ALL ... Fix the tune... with the wrong OS it could be Starting off in 2nd gear........When you say fix the tune, what do you mean exactly? As for the 4L80 segment swap, I do have a segmented tune, but I did not go that route. I am still running the 4L60 segment, and I modified the wiring harness and used a relay instead to control the 4L80. Please resend your contact info and I will call.
Yeh, they are hard to make perfect at idle. When the purge vent valve opens at idle, the PCM can not take enough fuel out, the STFT's max out, then when you open the throttle you get a lean stumble. I removed the purge valve and the 80's work better. I am also looking into getting a 2:1 boost referenced fuel pressure regulator so I can drop the fuel pressure at idle even lower. That should fix it after tuning.
Dont be Scared to run 22-24+ degrees to timing at idle and in park... Mine was tripple wrapped but the same Stock manifolds... 2.5" Y pipe with 3" feeding the turbo... Yes i do have a Blanket... With the Rear mount More timing is a MUST .. 2-4 more all over to get it to make Heat,Cylinder pressure and Boost.. I am going to Guess you Either have a Circle D 1A or 1B converter... I have a 1A and its VERY tight... 1800 stall..2500ish on the footbrake. i have to STAND on it to see 3200 before i get on the transbrake... Throw lots of timing at it early .. and like everyone else says 13.0 A/F... but mine would never make that without KR ... So i had to settle of 12.5ish... Mine was also 155psi cranking.. but only 9.2:1 compression with a 23X , 23X 600 600 115 installed at a 114 ICL... I wanted it around 110 ICL.... also i had 245cc heads, vic jr...
Thats were I should have put it in the first place. 
Oh, that 155 compression was when I fist got the engine from the builder. It had a 230/240 114 60? 59? cam in it. I can not remember the ICL but I did check the degree with the cam card and it was right on the money. That was the NA cam. I have not rechecked the compression since because there has not been any indication as to a leackage issue. No blowby, no nothing. I could check it tomorrow. I would expect it to have come up some with the cam swap, less valve overlap, less blead off.