Generation III Internal Engine 1997-2006 LS1 | LS6
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What Makes the #7 Piston Weak?

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Old 06-03-2005, 07:38 PM
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Is there a way with one of the editing programs to add a individual cylinder fuel trim? In other words richen up the flow rate from #7 injector. I know some stand alone units have this feature but am unsure about Edit or HP Tuners.
Old 06-03-2005, 07:44 PM
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The intake design gives a straight shot to #7. tends to run leaner than the other holes. Some guys run a slightly larger injector in that cylinder.

Old 06-03-2005, 08:05 PM
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Originally Posted by PREDATOR-Z
We have similar problems on #7 and #8.
Also they seem to spin rod bearings there more than other Cyl.
Is it a pretty common problem with LS1's or is it rare? I'm not really up to speed on the boosted scene, don't recall hearing much about it before. Just curious.
Old 06-03-2005, 08:35 PM
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Is there a way with one of the editing programs to add a individual cylinder fuel trim? In other words richen up the flow rate from #7 injector. I know some stand alone units have this feature but am unsure about Edit or HP Tuners.
No that is what I was talking about not with edit or HP tuners just over all fuel.
Old 06-03-2005, 09:04 PM
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then how do you tune for the bigger sized injector if its just on one or two cyls?
Old 06-03-2005, 09:40 PM
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you would not tune for the bigger injector or it would defete the reason for putting the bigger one in there

if only 1 cylinder is lean then if you put the bigger injector in there it will put more fuel inthere then the others because the computer thinks its the same size as the others therefor staying open the same amount but putting more fuel in
Old 06-03-2005, 11:00 PM
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I am just trying to clarify. You guys are basically saying that one should get all 8 of the injectors flow bench tested and mark the flow for each. Of the highest flowing, put the highest for #7 and maybe the second highest for #8. Does this sound correct?
Old 06-10-2005, 12:28 PM
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do 28.8# in cylinders 1-6 and 30# in cylinders 7 and 8. That'd be my guess. Im running 30# all the way accross on aftermarket rails.

Anyone have a link to the aussie ITB setup for the Ls1? i had the link saved a while back, but lost it..
Old 06-10-2005, 12:43 PM
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http://www.harrop.com.au/root_folder..._manifold.html
BTW, I would not put 2 different types of injectors on one motor, just the ones that flow best in the back.
Old 06-10-2005, 01:15 PM
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Originally Posted by PREDATOR-Z
There is a solution:

ITBs, one TB for every cylinder. Aussies have a good grasp of that, but setups are still expensive.
Redline Fuel Systems in Torrence CA is working on those set-ups, I should actually be offering them soon, if I ever get an LS car, mine be one of their doners...
Old 06-10-2005, 04:06 PM
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Originally Posted by PREDATOR-Z
http://www.harrop.com.au/root_folder..._manifold.html
BTW, I would not put 2 different types of injectors on one motor, just the ones that flow best in the back.
linky not working
Old 06-11-2005, 03:34 AM
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Th is happened to me. That is the reason for the mods in sig lol...I don't have mine apart but it doesn't sound like a spun bearing, doesn't sound like a ring land either though, it "ticks" until it gets to 2,000-2,500 RPM's and then it goes away.

I had a mustang pull up at the house, a friend of mine, and said "I heard the n2o killed the chevy" laughing, and I told him that it still beat his Mustang knocking, and it did lol. I normally pull 1.5-2.0 secs in the 1,000ft, but after this it was 1.0-1.5 secs. So I have lost power somewhere, or he has picked some up. he said he put a new tb on his though. Who knows? I did it with a 100 shot dry, not enough to hurt the engine...I didn't think.
Old 06-11-2005, 10:21 AM
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Cooling problems (hot pockets in heads and/or block) maybe?
Old 06-11-2005, 11:56 AM
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#7 and #8 were also a problem on LT1's... I busted the #7 and #8 piston/rod in my LT1. Then I went and bought 2 LT1's and 1 of them had a busted rod on #7 and the other had a spun bearing on #7.. And lots of other guys said the same thing about their engines.. guess its just chevy luck!
Old 06-11-2005, 12:02 PM
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FWIW, we had a forged 382 #7 piston break at the ring land. No blower. No nitrous. Lunati piston. All we can assume is that the injector on that cylinder was bad
Old 06-11-2005, 12:09 PM
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Do you think the bigger/better flowing injector in #7 and #8 would fix this?
Old 06-11-2005, 12:27 PM
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Originally Posted by byrontaylor
Do you think the bigger/better flowing injector in #7 and #8 would fix this?
no, I think proper Air/fuel distribution to those cyl would fix that.
Old 06-11-2005, 12:37 PM
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So in this case the carb intake would be better? What would that do to gas milage I wonder?
Old 06-11-2005, 03:24 PM
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Odd injectors are not the answer IMO. Perhaps a custom fuel system with a feed line entering the rear of each rail is the best solution. This is the approach I usually take to a setup planning to make over 500rwhp safely.
Old 06-11-2005, 03:35 PM
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Originally Posted by Reckless
Odd injectors are not the answer IMO. Perhaps a custom fuel system with a feed line entering the rear of each rail is the best solution. This is the approach I usually take to a setup planning to make over 500rwhp safely.
Not a bad ideal, what size lines would you run to each injector?



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