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7 Cyl LS1 Mystery solved!

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Old 05-28-2008 | 10:06 PM
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From: LT1 land...the "409" of the 90s!
Default 7 Cyl LS1 Mystery solved!

Well We tore down another seven Cylinder today. Looks like we found the issue.

Much Like rookies car this Firebird Ram Air car started running on Seven Cylinders for no apparent reason. Un-Like Rookies car it did not send a piece of the ring through the top of the piston and hurt other parts. Yes that is what was found in the cylinder guys

This car ran fine then started to slowly run on only seven cylinders. Seemed to have a Knock also. Well we inspected the engine and started our test. Our tests were ended short when we got to number five and could only muster 10Psi of compression.

Today we get the engine out and nothing really looks out of the ordanary until we remove the offending piston.



What you see is where the ring butted and then over lapped many many miles ago. The ring lands are not only broke but completely missing and the little chunks are what is left of the missing section of the second ring.

This makes three that I can think of just in our area.
Old 05-28-2008 | 11:04 PM
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wow interesting to see it happen to someone else in the area. We went with a more open gap that's for up to a 150 shot which is about what I'll put on when I get the juice. What year was this out of curiosity?
Old 05-28-2008 | 11:08 PM
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Originally Posted by TwoFast4Lv

This makes three that I can think of just in our area.
Don't say **** like that, you will curse all...
Old 05-28-2008 | 11:13 PM
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LOL Lane!

this one is a 01 as is the other one I am thinking of. ALL Ram Air cars
Old 05-28-2008 | 11:17 PM
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I don't think RAM AIR has anything to do with it, just a coinencadence..<<<I totally spelt that wrong but who cares. lol
Old 05-28-2008 | 11:22 PM
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Originally Posted by crazylane
I don't think RAM AIR has anything to do with it, just a coinencadence..<<<I totally spelt that wrong but who cares. lol
Ram Air cars actually have a slightly different tune then Non-ram air cars only other thing they had in common so far besides Pontiacs and f-bodys
AND To answer the next question,


NO I did not tune any of them LOL!
Old 05-28-2008 | 11:30 PM
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The number 7 cylinder in our cars are notorious for having injector problems. Thus resulting in this.

Just a thought...
Old 05-28-2008 | 11:37 PM
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Originally Posted by crazylane
The number 7 cylinder in our cars are notorious for having injector problems. Thus resulting in this.

Just a thought...
Navy guys thinking, you don't get paid for that. Stop before you develop some intelligence. LOL

On topic: I imagine that would cause some power loss and a little noise though. I hope we haven't all been cursed. I all ready bent a rod on startup.
Old 05-28-2008 | 11:39 PM
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LOL not on this one Lane. We have had five and six so far
Old 05-28-2008 | 11:42 PM
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Originally Posted by The Manalishi
Navy guys thinking, you don't get paid for that. Stop before you develop some intelligence. LOL

On topic: I imagine that would cause some power loss and a little noise though. I hope we haven't all been cursed. I all ready bent a rod on startup.
I bet thats what you army guys say everytime you guys get in any kind of trouble, and have to ask us for intel??? ha ha
Old 05-28-2008 | 11:50 PM
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Originally Posted by crazylane
I bet thats what you army guys say everytime you guys get in any kind of trouble, and have to ask us for intel??? ha ha
LMAO. Thats a good one.
Old 05-29-2008 | 12:40 AM
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interesting how these three are all 01s and ram airs. And that piston looks like the ls6 piston that came out of mine too.


any other commonalities? aftermarket cam? aftermarket tune? I think mine happened when an O2 sensor failed and I didn't know about it because the check engine light was on all the time from the SD tune.
Old 05-29-2008 | 12:44 AM
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Wasn't 01 one of the worst years for piston knock? I know one of the guys who had his Ram Air car get the pistons replaced under warranty with the coated Z06 pistons
Old 05-29-2008 | 12:47 AM
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I honestly don't see how a factory tune can do this, and only to this cylinder.

How much different is the Tune in a Ram air car?? Can't be much different than what others are running.
Old 05-29-2008 | 12:49 AM
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I don't think it's the number 7 cyl it just brought the engine down to running on 7 cylinders. Mine was like the number 3 cylinder or something. And 01 was the model year they started that program of piston replacement, customers had complained so much since the piston slap thing started, and GM replaced them with the coated pistons. Which I think a pissed a lot of people off who owned them prior to that and had piston slap issues. I know my 99 had horrible piston slap at times.
Old 05-29-2008 | 12:54 AM
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mybad, its the number 5 cylinder.. not 7.

But still I can't see how a stock tune can do it. idk...
Old 05-29-2008 | 12:54 AM
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Originally Posted by crazylane
I honestly don't see how a factory tune can do this, and only to this cylinder.

How much different is the Tune in a Ram air car?? Can't be much different than what others are running.

Not much lane. And it is not just one cylinder in particular it seems random like the rods that are starting to break. It looks like the Rings did not have enough gap and butted breaking the ring lands. It is odd that so far all we have seen is Ram Air cars. Looking at the complete errosion(sp) of the ring land and piston this one broke a long time ago. Who knows it May have ran hot once and the rings locked.

To much damage now to know for sure.

Maybe we will see four or five stock Z28 cars next
Old 05-29-2008 | 12:54 AM
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Mine is an 01 Ram Air car and while mine didn't eat a ring land it did bend a rod on startup and the only thing I can figure is the injector hung open. Maybe its the same problem with a little different circumstance. The ring lands may have been stronger than the rod in my case and in others the ring lands was the weak link. Not saying rods or ring lands are stronger or weaker but if there was a weak spot on either part and it let go it would release the pressure of that cylinder being flooded. Just a thought. Mine never made any noise, had piston slap or any abnormality. It was #5 cylinder also.

Lane I know us Army guys aren't supposed to think either.
Old 05-29-2008 | 12:59 AM
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Originally Posted by The Manalishi
Mine is an 01 Ram Air car and while mine didn't eat a ring land it did bend a rod on startup and the only thing I can figure is the injector hung open. Maybe its the same problem with a little different circumstance. The ring lands may have been stronger than the rod in my case and in others the ring lands was the weak link. Not saying rods or ring lands are stronger or weaker but if there was a weak spot on either part and it let go it would release the pressure of that cylinder being flooded. Just a thought. Mine never made any noise, had piston slap or any abnormality. It was #5 cylinder also.

Lane I know us Army guys aren't supposed to think either.
Thats the smartest thing I have seen come from you!!!! But I will give you credit, you thought hard enough to tell me the truth on the matter.... lmfao..
Old 05-29-2008 | 01:01 AM
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Better Watch out for us slow ARMY guys Lane



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