LBZ: Question for twin owners

[05chevy]

S475 over stock. 60% injectors. Truck will only make 38psi at wot and will hit 1300* quick. Tune is nothing real crazy. Actually all of the tunes will hit high egt's fast.

I'm going to pressure test the intercooler to see if it is leaking. Does anyone have a idea of what would be the problem?

 

[PACougar]

1300* isn't very hot, did it use to run differently?

 

[DuramaxPowered]

38psi is really low. Mine would make 55-58 on stock fuel and egts would stay down in the 1200 range umless I ran it to 100+mph. Exhaust or boost leak is where Id start.

Sent from my SCH-I605 using Tapatalk 2

 

[PACougar]

Is your setup gated?

 

[hondarider552]

Whos tuning? Timing map up to par with fuel amount?


id start at the inlet to the stock turbo, seen a few twin kits leak there as well as the Y bridge.

 

[blk smoke lb7]

sure your boost gauge is accurate? 38 is pretty low but your truck is hauling ass for not alot of boost.High egts is to much fuel or to much air correct? time to talk to your tuner,or try a new tuner.If you do have a boost leak it would explain the higher egts but if thats the case your truck is gonna get a whole lot faster when you find that 12 to 14 psi your loosing.

Are lly intercoolers like the lb7s,leak down in the corner from stock?Have you boost tested your set up yet?

 

[05chevy]

there are no exhaust leaks.

the set up is not gated.

This is the first twin setup I have tuned. I modifed the timing table as anyone would for larger injectors. Do twins set up like more or less timing?

The boost gauge read 35 psi with only the stock setup before the twins. I took the boost gauge and hooked in the compressor housing of the large turbo and it would only build boost around 3/4 to wot throttle. and only see 20psi. i have not tested the intercooler yet.

i will check the connection to the small turbo because he had that off due to a return like leak. before he fixed that the truck would see 45psi.

 

[blk smoke lb7]

there are no exhaust leaks.

the set up is not gated.

This is the first twin setup I have tuned. I modifed the timing table as anyone would for larger injectors. Do twins set up like more or less timing?

The boost gauge read 35 psi with only the stock setup before the twins. I took the boost gauge and hooked in the compressor housing of the large turbo and it would only build boost around 3/4 to wot throttle. and only see 20psi. i have not tested the intercooler yet.

i will check the connection to the small turbo because he had that off due to a return like leak. before he fixed that the truck would see 45psi.

your either loosing drive pressure from the valley turbo to the big turbo or your loosing boost from the big charger to the valley turbo sounds like to me.

Yup trucks gonna get faster lol

 

[LBZrcks]

Did you open up the vane position in the tune?

 

[Chevy1925]

Did you open up the vane position in the tune?

X2. Sounds like the issue is a combo of a little boost leak and vane position not corrected for twins. without two boost gauges it can be harder to tune the vanes in right

 

[05chevy]

Did you open up the vane position in the tune?

No we have not changed the vane position in the tune.

Should I open up the whole table of just high rpm?

 

[LBZrcks]

No we have not changed the vane position in the tune.

Should I open up the whole table of just high rpm?

Try opening them all the way as soon as possible, start off at ~2400 RPM then see if you can open them sooner without making it too laggy.

 

[SickLL7Crenshaw]

My LLY with s475 over stocker will touch 1450 on my 2300PW tune and boost holding at 45-48 spiking at 52. Vane position tables wasn't changed when I got my tunes reworked for the twins...?? Should the vanes be opened up in higher rpms? When towing I see a easy 1250-1300 on 1800PW tune towing 10k at 65-70mph seems hot to me but idk?? My 2700PW tune will hold boost at 52 so I know I don't have a boost leak. that tune will touch 1500*

 

[Burn Down]

sure your boost gauge is accurate? 38 is pretty low but your truck is hauling ass for not alot of boost.High egts is to much fuel or to much air correct? time to talk to your tuner,or try a new tuner.If you do have a boost leak it would explain the higher egts but if thats the case your truck is gonna get a whole lot faster when you find that 12 to 14 psi your loosing.

Are lly intercoolers like the lb7s,leak down in the corner from stock?Have you boost tested your set up yet?

Yes, the LLY intercooler is the same and will leak in the corners... I'm sure mine is leaking there as well. I will fix or replace the intercooler whenever I get around to building my engine

 

[Burn Down]

My LLY with s475 over stocker will touch 1450 on my 2300PW tune and boost holding at 45-48 spiking at 52. Vane position tables wasn't changed when I got my tunes reworked for the twins...?? Should the vanes be opened up in higher rpms? When towing I see a easy 1250-1300 on 1800PW tune towing 10k at 65-70mph seems hot to me but idk?? My 2700PW tune will hold boost at 52 so I know I don't have a boost leak. that tune will touch 1500*

I would have to check my tune when I get home but pretty sure Reece and Tony opened up the vanes on my 4094 when we worked over my race tune for the bigger turbo's... My setup will differ from yours and the op's as your setups will spool instantly compared to mine... I had a 4202R over a stocker before this setup. I would guess that you guys could open the vanes alot sooner than I can on the 4094. I also have 2 boost gauges Hi, Lo, & Drive to help dial in the tuning.

 

[SickLL7Crenshaw]

ya let me know cuz this thread has got me curious..

 

[SickLL7Crenshaw]

sub'd

 

[catman3126]

subd

 

[SickLL7Crenshaw]

Nevermind. On LLY the B2225 table needs to be changed for the vanes on a twin setup over stock vvt. or that was the other vane table changed for my twins

 

[Sledhead]

My 2700PW tune will hold boost at 52 so I know I don't have a boost leak.

Not necessarily, I still made 47 (down from 50) with my intercooler leak. I figured the leak was like feeding a 9th cylinder just some lag and smoke at low rpms.