Low rwhp on twin turbo setup
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.
My goal was 800 rwhp at around 6500 rpms.... Someone said to turn up the boost but i didn't only because i did not expect the power to decrease so much after 5300 rpms on 12 pounds of boost.
Also what kind of valve springs do you have? Maybe also switch back to stock rockers since the yella terras might be causing some valve float due to marginal springs, high exhaust backpressures, etc.
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.
the tuners printer took a dump so no sheets right now.... The cam is small but i sure thought it would peak higher under boost. thanks t
Trending Topics
Staging Lane
Joined: Feb 2010
Posts: 58
Likes: 0
From: Dallas Tx
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
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo 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
Staging Lane
Joined: Feb 2010
Posts: 58
Likes: 0
From: Dallas Tx
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
The power declined steadily. It ended up at 460's around 6500 rpms. I have the ls6 intake so i'm supposed to be good there. I didn't check my air filters to see if they were collapsed or not but i'll do so today. t
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.
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.
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.
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.