JE Piston article on 3.900 stroke cranks
03-16-2018, 07:17 PM
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JE Piston article on 3.900 stroke cranks I stumbled across this article on google and I was wondering if anyone has done any measuring or can validate this info on 3.900 crankshafts in ls blocks.
I’ve read/heard before that 4.000 stroke causes the piston rings and the piston skirt to swipe the bottom of the cylinder which causes premature wear/failure. This article is saying that with a 3.900 crank (which is kind of an odd stroke) you don’t get that rub on the bottom of the cylinder.
I asked two Representatives about this info on the phone but they both said they haven’t heard this before. I’m curious if a 3.900 crank is more safe because I’m building an LQ9 turbo motor and replacing the crank so if I can safely stroke it while I have it torn apart I would like to.
http://blog.jepistons.com/different-...nk-for-your-ls
I’ve read/heard before that 4.000 stroke causes the piston rings and the piston skirt to swipe the bottom of the cylinder which causes premature wear/failure. This article is saying that with a 3.900 crank (which is kind of an odd stroke) you don’t get that rub on the bottom of the cylinder.
I asked two Representatives about this info on the phone but they both said they haven’t heard this before. I’m curious if a 3.900 crank is more safe because I’m building an LQ9 turbo motor and replacing the crank so if I can safely stroke it while I have it torn apart I would like to.
http://blog.jepistons.com/different-...nk-for-your-ls
03-19-2018, 09:07 AM
#2
I stumbled across this article on google and I was wondering if anyone has done any measuring or can validate this info on 3.900 crankshafts in ls blocks.
I’ve read/heard before that 4.000 stroke causes the piston rings and the piston skirt to swipe the bottom of the cylinder which causes premature wear/failure. This article is saying that with a 3.900 crank (which is kind of an odd stroke) you don’t get that rub on the bottom of the cylinder.
I asked two Representatives about this info on the phone but they both said they haven’t heard this before. I’m curious if a 3.900 crank is more safe because I’m building an LQ9 turbo motor and replacing the crank so if I can safely stroke it while I have it torn apart I would like to.
http://blog.jepistons.com/different-...nk-for-your-ls
I’ve read/heard before that 4.000 stroke causes the piston rings and the piston skirt to swipe the bottom of the cylinder which causes premature wear/failure. This article is saying that with a 3.900 crank (which is kind of an odd stroke) you don’t get that rub on the bottom of the cylinder.
I asked two Representatives about this info on the phone but they both said they haven’t heard this before. I’m curious if a 3.900 crank is more safe because I’m building an LQ9 turbo motor and replacing the crank so if I can safely stroke it while I have it torn apart I would like to.
http://blog.jepistons.com/different-...nk-for-your-ls
“One thing to note, is that the 4.000-inch stroke is the most popular out of all stroker LS combinations. So even with the added wear, most builders and racers are willing to accept this.”
While the article isn't exactly untrue, it does leave a lot of other variables out. Some of the latest piston technology and designs make the difference negligible.
03-20-2018, 10:22 AM
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Piston Skirt Length Hi ALL, I agree with KCS AND the SIMPLE FACT of the difference in a Piston Skirt Requirement Length OF >.050" shorter OR that of a Spark Plug Gap WHEN a 4.00" Crankshaft is compared to a 3.90" crankshaft piston.
The setup is simple, install ONE rod/piston without rings and observe the bottom of the cylinder for piston position.
Machine the piston skirt, if necessary, to keep the piston inside the cylinder.
I fit Racetech Pistons.
Lance
The setup is simple, install ONE rod/piston without rings and observe the bottom of the cylinder for piston position.
Machine the piston skirt, if necessary, to keep the piston inside the cylinder.
I fit Racetech Pistons.
Lance