Ls 3 cylinder walls cracked

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sccagt1racer
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Ls 3 cylinder walls cracked

Post by sccagt1racer »

Is it common for a ls3 bored to 4.070 to crack the cylinder walls vertically? #3 and #5 . The build is 11.2 to 1. cathedral port trick flow heads, ls6 intake, dry sump 7400 rpm's road race use. 450 hp 445tq at the rear wheels. It also has been losing the ground straps off the spark plugs. I suspect the tune has too much timing. Detonation?
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peejay
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Re: Ls 3 cylinder walls cracked

Post by peejay »

sccagt1racer wrote: Tue Sep 10, 2019 8:07 pm Is it common for a ls3 bored to 4.070 to crack the cylinder walls vertically? #3 and #5 . The build is 11.2 to 1. cathedral port trick flow heads, ls6 intake, dry sump 7400 rpm's road race use. 450 hp 445tq at the rear wheels. It also has been losing the ground straps off the spark plugs. I suspect the tune has too much timing. Detonation?
The only time I ever lost the ground straps from the plugs, I was way off on the heat range because I didn't know any better, yet. Was running NGK 6-range plugs on an engine that needed -10s.
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needforspeed66gt
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Re: Ls 3 cylinder walls cracked

Post by needforspeed66gt »

Very uncommon, I see it with the LS7 blocks all the time, but only on one of the cast in place liner blocks if the tune was grossly off and resulted in nonstop detonation cycles. Look in through that water jacket passage and see if there's a crack in the aluminum right behind the cracked sleeve, the LS7 engines almost always crack both...the cylinder pressure spikes blow out the liner and the aluminum support for the sleeve cracks, then the actual liner cracks afterwards.
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Re: Ls 3 cylinder walls cracked

Post by A_VAS »

I've only seen that with LS2/3 blocks if a valve drops or piston chunk gets stuck between piston/head.

not seen it with detonation on engines that I know were detonated....so I'd say that's uncommon.

when I find a cracked one as mentioned, I save the blocks to use for Darton sleeving projects down the road
too lazy to make power w/o boost
sccagt1racer
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Re: Ls 3 cylinder walls cracked

Post by sccagt1racer »

I got the engine fully torn down today. 6 out of 8 were cracked. The front cylinders were the only ones that were not cracked. The thrust side of the rod bearings have wear and the rest of the bearing looks normal. excessive detonation. The tune was not correct is what im going with on this one.
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