Bluchevypick

iTrader: (65)

As everyone knows, i built a turbo kit for my truck a while back. Every since i have had nothing but problems.

The day i built the kit and started it i realized i had blowby. I guess from the nitrous. So i pulled the motor out to find two pistons busted due to the rings touching. Well, i put two more pistons in it thinking it was just due to the nitrous. Two weeks later it does it again. So, i pull motor back out and replace pistons again and install new rings gapped at .030 top and second ring, .041 cometic head gaskets, fresh 317 heads, 160 thermostat, and i put a coolant crossover tube on the rear also.

Well, i finally felt good about it and took it to the track last night on 10#s. Very first pass it started missing so i let out of it. I limped it home and did a leakdown test today to find number 7 leaks over 50psi. Im soo sick of this. My tuner or machine shop dont know why.

00ChevyScott

iTrader: (10)

Weak fuel injector on #7?

MikeGyver

iTrader: (5)

What kind of pistons?

Bluchevypick

iTrader: (65)

Stock pistons. Lq9. Scott, i wouldnt think so but never know. The injectors were new.

00ChevyScott

iTrader: (10)

Had you ever pulled the plugs and compared all the cylinders to make sure any of them weren't going lean?

I know #7 has some crazy theories on why it's usually the first one to go. Some say it's because the coolant doesn't cool that cylinder well, others say it's because the intake manifold doesn't balance out airflow well on #7 intake runner. I've read a lot of theories on it, but there isn't any 100% hard data on it that I'm aware of.

Bluchevypick

iTrader: (65)

No i havent, but the weird thing is...the first time it was number 5 and 7. The second time it was 1 and 7 and now its just number 7

dlt76028

iTrader: (13)

If everything was setup properly, I would look at the tuner. How much experience does he have with FI LS1 engines?

Doobie

iTrader: (2)

I have checked all my plugs closely when it was NA and since I installed a radix manifold on it and #7 plug has always showed a lighter color than all the rest. This indicates to me that it is a coolant flow issue and not an air flow problem as #7 is running hotter than all the other cylinders despite having different intake manifolds on it. All my other plugs are virtually identical in color with the exception of #7 that is always lighter/whiter than all the rest. I installed a 180* t-stat and use water-wetter in my coolant hoping for a little more protection/assurance that #7 doesn't I will be installing larger fuel injectors soon (I hope) but I don't think this will make any difference as this problem seems to be all to common.

Bluchevypick

iTrader: (65)

My tuner is very experienced. He tunes on over 125 cars and most of them are FI. We only had 16 degrees of timing and my air fuel was around 11.7 at wot. I put a coolant crossover on the back cylinders hoping to fix the coolant problem.

Gadgetized

iTrader: (9)

What is your fuel system like? Are you running the stock line? Where is your regulator mounted? Are the fuel rails tied together at the front and the back? Have you checked your pressure at WOT? I am a firm believer that you can never have enough fuel volume especially on a FI engine.