ls3 based 427 questions
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TECH Regular
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From: new york
ls3 based 427 questions how safe are these on nitrous ? i just sent my setup out to get balanced etc . its a callies crank , scat h beams , wiseco pistons all forged obv with hellfire rings . my heads are livernois stg 3 l92 cnc ported heads , custom grind tooley cam . running a nitrous outlet money maker nitrous kit . i want to run at last a 100 shot and at most a 200 hit but i keep hearing walls are thin and not a wise choice .
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I think the problem is how far the pistons stick out the bottom of the sleeve. They tend to rock more in that location. That is why most only recommend a 4" stroke. For normal operations and reasonable rpm probably not to big of a deal. With power adders and higher rpm then the reliability component more than likely gets shorter.
I don't have any personal experience, just what I have read.
I don't have any personal experience, just what I have read.
I would be worried about your tune/nitrous setup more then the piston rock
The piston top ring land tends to get to thin for alot of nitrous but you are fine on a 150#
4" and 4.125" stroke pistons stick tha same amount out of the bottom
i´ve done plenty if 4.125" stroke motors and they are just as bad as the 4"
Aluminum blocks are so much weaker then the cast iron clumps,any detonation and the cyllenders distorts permanently and crack,It can live but only with a good tuner
The piston top ring land tends to get to thin for alot of nitrous but you are fine on a 150#
4" and 4.125" stroke pistons stick tha same amount out of the bottom
i´ve done plenty if 4.125" stroke motors and they are just as bad as the 4"
Aluminum blocks are so much weaker then the cast iron clumps,any detonation and the cyllenders distorts permanently and crack,It can live but only with a good tuner
Last edited by Ari G; Jun 7, 2014 at 12:14 PM.
I've seen conflicting info on ls3 sleeve length, I thought they were a tad longer than the ls2 and lq's but lately I've been researching for a stroker build and see a lot of people claiming they are the same length, can you guys confirm this?
I would be worried about your tune/nitrous setup more then the piston rock
The piston top ring land tends to get to thin for alot of nitrous but you are fine on a 150#
4" and 4.125" stroke pistons stick tha same amount out of the bottom
i´ve done plenty if 4.125" stroke motors and they are just as bad as the 4"
Aluminum blocks are so much weaker then the cast iron clumps,any detonation and the cyllenders distorts permanently and crack,It can live but only with a good tuner
The piston top ring land tends to get to thin for alot of nitrous but you are fine on a 150#
4" and 4.125" stroke pistons stick tha same amount out of the bottom
i´ve done plenty if 4.125" stroke motors and they are just as bad as the 4"
Aluminum blocks are so much weaker then the cast iron clumps,any detonation and the cyllenders distorts permanently and crack,It can live but only with a good tuner
Thread Starter
TECH Regular
Joined: Jun 2009
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From: new york
my boss is my tuner , i work at a small perf shop and tuning facility called coppola motorsports here in n.y and my boss is exc with a tuner he has done all my previous setups along with many friends setups so im very comfy with his abilities
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TECH Junkie
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Going by the posts of people who build the motors the pistons do stick out of the sleeve more at the bottom end. Yes, you can compensate some by moving the pin up towards or into the rings but it is not enough to prevent more of the piston from sticking further out of the bottom of the sleeve. The ever so slightly more piston rock will cause the rings not to seal quite a good. Just reporting what the engine builders are saying. A 4" stroke is about it for proper sealing on an LS3 block.
Going by the posts of people who build the motors the pistons do stick out of the sleeve more at the bottom end. Yes, you can compensate some by moving the pin up towards or into the rings but it is not enough to prevent more of the piston from sticking further out of the bottom of the sleeve. The ever so slightly more piston rock will cause the rings not to seal quite a good. Just reporting what the engine builders are saying. A 4" stroke is about it for proper sealing on an LS3 block.
I think you may have misunderstood what some of these builders have stated about these combinations.
Last edited by KCS; Jun 8, 2014 at 01:16 PM.
You have to compare apples to apples
This has been thrown out there so many times but its not right what people are saying
i´ve stumped people with this on 2 assembled motors,the skirts dose not stick out any further wiseco vs wiseco pistons
The brakeover point on the longer stroke piston is higher with the different taper and shorter C/H desinged into it and rides on the same spot as the 4" piston,rock is the same and can be measured.
Rock is caused by piston taper/skirt desing not how much is sticks out
This has been thrown out there so many times but its not right what people are saying
i´ve stumped people with this on 2 assembled motors,the skirts dose not stick out any further wiseco vs wiseco pistons
The brakeover point on the longer stroke piston is higher with the different taper and shorter C/H desinged into it and rides on the same spot as the 4" piston,rock is the same and can be measured.
Rock is caused by piston taper/skirt desing not how much is sticks out
Might have helped if you'd have stated using pistons with different skirt lengths. FWIW, the extra stroke going from 4.00" to 4.125" (0.0625") will pull the pin down that much farther. As noted, this can be compensated for by shortening the skirt...
I would be worried about your tune/nitrous setup more then the piston rock
The piston top ring land tends to get to thin for alot of nitrous but you are fine on a 150#
4" and 4.125" stroke pistons stick tha same amount out of the bottom
i´ve done plenty if 4.125" stroke motors and they are just as bad as the 4"
Aluminum blocks are so much weaker then the cast iron clumps,any detonation and the cyllenders distorts permanently and crack,It can live but only with a good tuner
The piston top ring land tends to get to thin for alot of nitrous but you are fine on a 150#
4" and 4.125" stroke pistons stick tha same amount out of the bottom
i´ve done plenty if 4.125" stroke motors and they are just as bad as the 4"
Aluminum blocks are so much weaker then the cast iron clumps,any detonation and the cyllenders distorts permanently and crack,It can live but only with a good tuner
TECH Junkie
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You guys are right with the newer pistons. However I would not want to use a power adder. If doing a power adder I would drop back down to a 416" motor.
Hmmm, I might consider a 427 short block now that my L92 has given up the ghost due to rod knock.
Hmmm, I might consider a 427 short block now that my L92 has given up the ghost due to rod knock.
Thread Starter
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From: new york
well i ordered pistons from d.s.s today and they said the same thing on comp height . i should be safe and not have any or very little protrusion at the bottom of sleeve as they raise the pin and shorten skirt etc . when i get them in ill post pics as compaired to the wiseco i had on origanally