Power question. Turbo guys come in!
Power question/problem. Turbo guys come in! We have established that I have a backpressure issue but I am thinking I may have another problem as well. I have a 402 with a Turbonetics 76mm with a .96ar. There is no real power. I would guesstimate 380-400rwhp @ 10psi of boost. Could this all be the turbo being too small? Seems like alot of loss. Should I be looking somewhere else also? I have seen that Ninetres made 700rwhp with his 76 and a 364. I realize I am further out of the compressor map but that is a huge difference from mine. I was hoping to make it through the summer w/ the 76( low cash and car will be down for some time while the t-4 to t-6 swap) but will switch to a t-6 88 if the turbo it the whole problem. If not I want to find the other problem and make it through the summer with the 76.
I am running a ls2 block with -28cc pistons, stage 2 l-92 heads, and a l-76 intake. If I figured compression right it is 8.5 to 1. Also running a 4l80e and a 273 rear.
Thanks guys for any poss suggestions!
I am running a ls2 block with -28cc pistons, stage 2 l-92 heads, and a l-76 intake. If I figured compression right it is 8.5 to 1. Also running a 4l80e and a 273 rear.
Thanks guys for any poss suggestions!
Last edited by phildo; Jul 30, 2007 at 07:31 AM.
Something sounds very wrong. You should be making that much power on your motor alone. Have you checked your tune? Is the car running smooth? I would agree that the turbo is too small but it should still be making way more power.
It is running a air /fuel of 11.0 and about 16* timing. I am spraying straight meth. It runs o.k. at light throttle and 3-4 psi but anything more and it sounds funny and gets flat. If I hit it hard it will break the tires loose at first (1-5psi) then once it boosts past 4-5psi loose all power and torque (6-15psi) and get flat.The tires even stop spinning once the initial 1-4psi are surpassed.There is no knock retard.But the exhaust sounds funny when it looses power. Plugs are tr6's gapped at .035 so I don't think the spark is being blown out. I am at a loss!
I would go take it to the dyno and see what they can come up with... They need to scan this soon to be monster and see whats going on... Somethings DEF not right... You should be making upper 500's into the 600's on 5-7 psi with that motor......
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What A/R are you running?
Do backpressure test and see how its doing. Does the car overheat during 10psi runs? Locally, I've only seen 364ci guys running T76s, so I'm sure yours is out of range on that 408.
Do backpressure test and see how its doing. Does the car overheat during 10psi runs? Locally, I've only seen 364ci guys running T76s, so I'm sure yours is out of range on that 408.
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Verdad Gallardo .96 ar
No it does not overheat at 10psi. and IAT's do not climb but I have a massive intercooler and spray meth on top of that. My Iat's only get a couple degrees above ambient.
The only problem w/checking the pressure is there are only 2 02 bungs on my crossover pipe, so I would have to pull a o2 to do it. Would run pig fat on that bank but I guess I could try it. Who carries the gauge to measure pressure?
No it does not overheat at 10psi. and IAT's do not climb but I have a massive intercooler and spray meth on top of that. My Iat's only get a couple degrees above ambient.
The only problem w/checking the pressure is there are only 2 02 bungs on my crossover pipe, so I would have to pull a o2 to do it. Would run pig fat on that bank but I guess I could try it. Who carries the gauge to measure pressure?
Have you tried scaling back the meth (is it progressive)? You might want to use hi octane gas and try it w/o the meth, get the tune right, (full insturmented dyno runs)then begin to substitue meth and 93.
TECH Resident
Joined: Jan 2004
Posts: 832
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From: Castro Valley, CA
Dave beat me to it; it sounds like you may be spraying too much methanol too quickly. Ditto the above advice; turn off the methanol and get a base tune on higher octane fuel... and of course when you're back to normal fuel and methanol you'll probably need to pull some fuel out when the methanol is maxed out.
Even with a progressive (Alkycontrol) system, you can spoil your own party by adding too much too early as the car responds to WOT. That's why the little ramp adjustment **** on that controller is there. My system is set to ramp pretty slowly.
Even with a progressive (Alkycontrol) system, you can spoil your own party by adding too much too early as the car responds to WOT. That's why the little ramp adjustment **** on that controller is there. My system is set to ramp pretty slowly.
TECH Regular
Joined: Jan 2007
Posts: 408
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From: boostville
what kind of wastegate are you running and are you using a boost controller or just running of the WG spring pressure?
another thing you might want to try is a pressure test to see if you have any leaks in your charge piping.
another thing you might want to try is a pressure test to see if you have any leaks in your charge piping.
Launching!
Joined: Apr 2007
Posts: 279
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From: lynchburg va
Originally Posted by DaveSchott
Have you tried scaling back the meth (is it progressive)? You might want to use hi octane gas and try it w/o the meth, get the tune right, (full insturmented dyno runs)then begin to substitue meth and 93.
Can you change the AR to a bigger one? If not, turn it down and leave it alone until you can fit a bigger turbo. Why not do a T4 88, T6 is a bigazz turbo, mine is almost 12x12x12 inches.
Originally Posted by RW99
cablebandit's sig is so frickin' funny I sat through it twice.
Originally Posted by wannasupra
how do you have your meth set up? also, how does the car sound flat? vid? datalog? graph?
It is like a car with a clogged cat converter. Has power till a certain load Than the exaust sounds flat or mono tone. Not crisp and aggressive.
A video will do nothing. Sound quality would be too poor.
Originally Posted by ddnspider
with that timing and A/F u shouldnt even need meth @ 10psi try not spraying meth AT ALL and see what happens.theres no way your backpressure is that high causing this problem.
I was just hoping someone had a similar situation and could shed some light on the situation. I am sure once I figure it out it is going to be something stupid but I will try anything to get to the bottom of this.