?Rear Mount Turbo? Help
Talk to Tick Performance Hope you have some bigger than stock injectors. And a new fuel pump like racetronix is good idea. You do seem to be dropping down pretty bad up top. Torque looks pretty nice though!
Valve springs are a good idea for sure. You can be getting valve float pretty easily with old springs.
Tune can be hiding a lot of power. Possibly you can still go a bit leaner a bit more timing. A few more pounds boost might be ok to around 8psi.
I would stay conservative on the stock engine. You still have around 500 engine hp at 20% and thats not too bad really. Too bad you can't put it thru the quarter mile and see what it can do. As said you also might be getting trans slippage the 4l60 are not great stock for high power.And not sure about the converter either how good a stock converter is. Once you go FI the costs start to add up !
You also need scanning in the car to see if you are getting knock retard. Make sure you are running premium fuel. Alc/meth injeciton might be a good addition as well. Safer and you can run a bit more timing and bit leaner if you want to.
Boost leaks for sure can hurt the power as well. Oh and buddies sts lost tons of power when the cat go clogged up. You really shouldn't run a cat with sts car. Car picked up at least 100hp when he cut out that clogged up cat!
Valve springs are a good idea for sure. You can be getting valve float pretty easily with old springs.
Tune can be hiding a lot of power. Possibly you can still go a bit leaner a bit more timing. A few more pounds boost might be ok to around 8psi.
I would stay conservative on the stock engine. You still have around 500 engine hp at 20% and thats not too bad really. Too bad you can't put it thru the quarter mile and see what it can do. As said you also might be getting trans slippage the 4l60 are not great stock for high power.And not sure about the converter either how good a stock converter is. Once you go FI the costs start to add up !
You also need scanning in the car to see if you are getting knock retard. Make sure you are running premium fuel. Alc/meth injeciton might be a good addition as well. Safer and you can run a bit more timing and bit leaner if you want to.
Boost leaks for sure can hurt the power as well. Oh and buddies sts lost tons of power when the cat go clogged up. You really shouldn't run a cat with sts car. Car picked up at least 100hp when he cut out that clogged up cat!
+1 on the cat idea to .. Turbo cars tend to clog the cat really fast and it can cause lots of damage if it come apart and goes through your turbo, I just took it for granted that everyone took those off 
Joined: Jun 2004
Posts: 1,501
Likes: 7
From: Ft. Irwin, California (But Virginia is home)
Check the following:
1. Pull the cold-side pipe by the turbo and see if there is oil in it. Also pull the MAF itself and see if there is an oil film on the wires. If yes, this is why your car is performing like stock. STS turbos pushing oil into the intake is a common problem (the return pump isn't always up to the task to scavenge the turbine adequately.) This will cause erroneous readings on the MAF, skew the fuel as a result..... and the car will run like it's stock.
The fix if you find this is to clean the oil out of the intake pipes + read the following thread I compiled last year: https://ls1tech.com/forums/forced-in...ust-pipes.html
2. If you can log it, check the IAT's. You said your STS in not intercooled. The cold-pipe running along the driver side of the car is not sufficient to cool the intake charge. It passes along the driver side cat converter and the radiator/ power steering cooler which re-heats the air. A FMIC is a must. I logged my STS non-intercooled in 2006. I was seeing IAT's upewards of 150+ with ambient temps of only 80 degrees outside. The PCM will begin pulling timing above 100 degrees. The PCM heavily favors IAT's (vs coolant temp) for timing. So, with 150+ degree IAT's, the PCM might be pulling as much as 7-10 degrees timing, which will murder your HP. You can log these values with a program like HP Tuners or even a Diablo Predator programmer.
3. I can't see your dyno pic here at work, but if Zombie is saying your graph falls on it's face above 5200RPM's and looks like valve float, then that's probably the case. Stock springs won't cut it on a STS. Neither will the stock injectors/fuel pump. I had to run 42lb/hr injectors on my setup and coupled that with an Aeromotive 255GPH in-tank pump. Once I swapped heads/cam, I had to run 60lb/hr injectors to meet fuel demands....and this was at only 5PSI.
I'd feel 90% sure that one of the above is your issue. As for claims on HP, for a stock car 396/423 is about right. You're not going to see 500+RWHP SAE from 6PSI on a stock-engine STS car, unless it's a "feel-good" dynograph.
Good luck to ya'.
1. Pull the cold-side pipe by the turbo and see if there is oil in it. Also pull the MAF itself and see if there is an oil film on the wires. If yes, this is why your car is performing like stock. STS turbos pushing oil into the intake is a common problem (the return pump isn't always up to the task to scavenge the turbine adequately.) This will cause erroneous readings on the MAF, skew the fuel as a result..... and the car will run like it's stock.
The fix if you find this is to clean the oil out of the intake pipes + read the following thread I compiled last year: https://ls1tech.com/forums/forced-in...ust-pipes.html
2. If you can log it, check the IAT's. You said your STS in not intercooled. The cold-pipe running along the driver side of the car is not sufficient to cool the intake charge. It passes along the driver side cat converter and the radiator/ power steering cooler which re-heats the air. A FMIC is a must. I logged my STS non-intercooled in 2006. I was seeing IAT's upewards of 150+ with ambient temps of only 80 degrees outside. The PCM will begin pulling timing above 100 degrees. The PCM heavily favors IAT's (vs coolant temp) for timing. So, with 150+ degree IAT's, the PCM might be pulling as much as 7-10 degrees timing, which will murder your HP. You can log these values with a program like HP Tuners or even a Diablo Predator programmer.
3. I can't see your dyno pic here at work, but if Zombie is saying your graph falls on it's face above 5200RPM's and looks like valve float, then that's probably the case. Stock springs won't cut it on a STS. Neither will the stock injectors/fuel pump. I had to run 42lb/hr injectors on my setup and coupled that with an Aeromotive 255GPH in-tank pump. Once I swapped heads/cam, I had to run 60lb/hr injectors to meet fuel demands....and this was at only 5PSI.
I'd feel 90% sure that one of the above is your issue. As for claims on HP, for a stock car 396/423 is about right. You're not going to see 500+RWHP SAE from 6PSI on a stock-engine STS car, unless it's a "feel-good" dynograph.
Good luck to ya'.
Teching In
Joined: Jul 2009
Posts: 7
Likes: 0
Good advice, with pressure built in the pipes you could also use a spray bottle of soapy water to find the leak also.
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Yea you need to upgrade valve springs.. but I would also still bet that you have a cold side boost leak. Do you feel the boost kick in around 3500rpms?
