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HOT AIR BALLOON OWNER
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Discussion Starter · #1 ·
How much nitrous or boost were you running before that piston decided to shit?

Was it from lack of fuel? Poor tune?

I'm just curious if 9psi is fairly safe on a stock block...
 

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It's not enough fuel, however you look at it. The average for the bank may end up being 11.5:1, but the ram effect of the air is forcing a larger volume into that back cylinder.

If you can get your fuel injectors flow tested, install the two largest ones in the back two cylinders, working your way forward to the two smallest ones in the front, should help with the problem.
 

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HOT AIR BALLOON OWNER
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Discussion Starter · #3 ·
Why not richen up the mixture at full throttle to drop power and lower EGTs?
 

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Why not richen up the mixture at full throttle to drop power and lower EGTs?
That's one solution, although EGTs aren't the primary concern though.

This isn't just a GM V8 problem. Any engine with a throttle body at the front of the intake manifold will experience the same air-ramming effect at the rear of the manifold. More air rushes in and piles into the farthest cylinders than makes it into the ones closer to the TB. So, unless you have fueling control over individual cylinders, those at the front will always run richer than those at the rear.

That is why you install the ever-so-slightly bigger injectors at the rear. They'll provide the extra fuel needed to keep things safe back there while allowing you to not have to overfuel the front cylinders.
 

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I don't think there are many on here who have lost it.

I was running 10 psi. It happened the instant that I ran out of meth. My tune was setup to pull timing, based on the IAT; but I guess I was on the ragged edge. I was playing with the timing and I bumped it up significantly. I dropped it back down to a middle ground for daily driving, but I went out for one night of fun, and bumped it back up. It made great power, right up until the moment it blew. :LOL: I was living very dangerously, and I knew it. It was my own greediness that contributed to the hole in my piston. I was planning a motor swap anyway, so it all kinda worked out.

With a good tune, I think 9-10 psi is perfectly safe.
 

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With a good tune, I think 9-10 psi is perfectly safe.
9-10psi or more. You didn't lose yours directly because of too much timing, you lost it because of too much heat. Meth ran out, all of a sudden you're cylinder temps skyrocket (function of excessive fuel is to pull heat out of the combustion chamber). Only 1/14.7 parts fuel can burn for every part air. If you have 1.47g of air in a cylinder, only .1g of fuel will burn. All excess fuel in the cylinder will function as a heat absorber.

With proper thermal control, the pistons will not be the weak link on a stockmotor.
 

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HOT AIR BALLOON OWNER
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Discussion Starter · #8 ·
I'm surprised no one has proto'd an aftermarket truck intake yet.
 
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