Low rwhp on twin turbo setup
#1
Low rwhp on twin turbo setup
Hello turbo guys... I dynoed this weekend and my numbers were less than impressive. I do not have a dyno sheet to show you but lets see if someone can still put me on the right track. Here is the combo: Rear mounted twin gt35r's t3 exhaust housing w/.63, stock sts piping, forged 370, 8.8 comp, fresh patriot stage 3 heads, 218/230 567/575 lift cut on 116 and installed at 116 i/c, a4 with 2800 vig conv, 3.42's... It made 620 rwhp at 110 mph which works out to approx 5250 or so rpms. We pulled it up to 6500 rpms and the power steadily declined after 5250 rpms.... The power dropped down to 460's at 6500 rpms.... 12 Pounds of boost. AFR's at 11.5's and the total timing was 18 degree at full boost. It runs great, it just doesn't make any power. Thanks for any help guys! Let me know if you need more info.
#5
hey 30th/nic, yes, it holds it smooth all the way up... both wastegates are screaming and the boost is steady. The patriots were just freshened by patriot and they said the springs were good although i did not check the rates. I have had valve float before with a different car and it would not rpm well at all but this thing revs fine up top but no power. We thought about backpressure but STRY (on corvette forum) has the same turbo's but a larger motor and had the exact same exhaust housings and made over 1000rwhp on the same rear mount. He was running more boost and had a larger motor so this may point to me upping the boost levels. Thanks for the replys.
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#8
i did a little math on my set up with the 35r's and its gonna take 17.5 psi to make 800 flywheel hp. that would mean the motor is moving about 44lb/min of air per turbo. i wonder if backpressure is not letting it breathe past 6000rpms? you can always check with a backpressure gauge. the turbines are a little small. at least mine are with 3in outlets and about 2.25 to 2.5 inlets
#9
i did a little math on my set up with the 35r's and its gonna take 17.5 psi to make 800 flywheel hp. that would mean the motor is moving about 44lb/min of air per turbo. i wonder if backpressure is not letting it breathe past 6000rpms? you can always check with a backpressure gauge. the turbines are a little small. at least mine are with 3in outlets and about 2.25 to 2.5 inlets
#11
also... did the power curve just peak and flatline? if so it could be an intake restriction. i had a 03 rustang that after 5300 would flatline on the dyno cuz it couldnt flow enough air thru the intake manifold
#14
TECH Veteran
iTrader: (3)
Boost leaks?
GT35s should be able to do like 1400 engine hp .
What about trans and converter..Is this a triple disc converter..? Are you locking it on the dyno? single disc pretty sure would simply fry. What trans..Maybe trans is not holding the power.
What about knock retard..did you see huge knock retard?
What about fuel up top.What are you running for injectors, pumps..?
I can't see that cam being much of limiting factor. And with FI the heads and intake don't matter hugely either just mostly give you more power at lower boost.
GT35s should be able to do like 1400 engine hp .
What about trans and converter..Is this a triple disc converter..? Are you locking it on the dyno? single disc pretty sure would simply fry. What trans..Maybe trans is not holding the power.
What about knock retard..did you see huge knock retard?
What about fuel up top.What are you running for injectors, pumps..?
I can't see that cam being much of limiting factor. And with FI the heads and intake don't matter hugely either just mostly give you more power at lower boost.
#15
Boost leaks?
GT35s should be able to do like 1400 engine hp .
What about trans and converter..Is this a triple disc converter..? Are you locking it on the dyno? single disc pretty sure would simply fry. What trans..Maybe trans is not holding the power.
What about knock retard..did you see huge knock retard?
What about fuel up top.What are you running for injectors, pumps..?
I can't see that cam being much of limiting factor. And with FI the heads and intake don't matter hugely either just mostly give you more power at lower boost.
GT35s should be able to do like 1400 engine hp .
What about trans and converter..Is this a triple disc converter..? Are you locking it on the dyno? single disc pretty sure would simply fry. What trans..Maybe trans is not holding the power.
What about knock retard..did you see huge knock retard?
What about fuel up top.What are you running for injectors, pumps..?
I can't see that cam being much of limiting factor. And with FI the heads and intake don't matter hugely either just mostly give you more power at lower boost.
#18
LS1Tech Sponsor
iTrader: (12)
The Compression is too low for 12lbs and a rearmount.For that compression it should be set to atleast 14lbs but I would run 16lbs on the street -pump gas.If the plan was 12lbs with this kit I would of recommended atleast 9.5-1 compression.
Up the boost a few lbs. I bet the power will jump nicely.
Up the boost a few lbs. I bet the power will jump nicely.
#20
The Compression is too low for 12lbs and a rearmount.For that compression it should be set to atleast 14lbs but I would run 16lbs on the street -pump gas.If the plan was 12lbs with this kit I would of recommended atleast 9.5-1 compression.
Up the boost a few lbs. I bet the power will jump nicely.
Up the boost a few lbs. I bet the power will jump nicely.