3.915 over bore issue...
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3.915 over bore issue... My LS1 is at the machine shop being rebuilt. Every thing is already paid for and I later learned that they are going with a 3.915 bore. This scares me because its a motor that sees 15+psi and makes 800 ish HP. Has anyone else pushed a bore this far on an LS1/6 block with good results? Since I'm already stuck with the custom pistons, should I trust them and go with it or pay the extra to have it resleeved and bored to that size? Can sleeves even have a bore as small as 3.915?
a 2618 aluminum piston (typical forged piston) likes a .005-.0055 piston to wall clearance for boosted setups... thats the avg..
so a stock ls1 bore is 3.898 and the recommended over bore is .010-.011 thats why you see alot of (3.908-3.910 piston setups)
so if your at 3.915 then your at .017 over bore and it could work for a NA car but I cant see why they would do that on a 800+ hp car
so a stock ls1 bore is 3.898 and the recommended over bore is .010-.011 thats why you see alot of (3.908-3.910 piston setups)
so if your at 3.915 then your at .017 over bore and it could work for a NA car but I cant see why they would do that on a 800+ hp car
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Reher Morrison in Dallas is doing the work. Pistons are forged JE. Not sure on planned clearances. Either way, I don't trust it at my power level and I'm going to take a hit. I'm gonna call them in the morning. Everything should be fine after sleeving it, right? I hate to do it for such a small bore but I really don't want to take the bigger hit on it when the block cracks. What does a sleeve job typically cost with sleeves and labor?
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They'll all last a long time unless you run it into detonation. Then all bets are off.
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Kind of what I'm thinking. 0.127 of a millimeter can't be too terribly bad but I also agree that the tune will have to stay pretty conservative. I'm just gonna let it ride. If it will last me a couple years, I will later throw in a larger cube shortblock.
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3.910 is max, so .005 more is a red flag? .0025 from each cylinder wall is going to make the difference?
They'll all last a long time unless you run it into detonation. Then all bets are off.
They'll all last a long time unless you run it into detonation. Then all bets are off.
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I know the limits as well as the risks. I also know people have gone beyond them with some luck. I am stuck with the build in progress. I would just like to hear from those who have pushed passed that mark and what did and didn't hold up.
If you decide to start over, just find another bare ls1 block on the cheap. It will be much cheaper than sleeving the current block and more durable IMO. Sleeving is not something to be taken lightly and I wouldn't trust most machine shops with that task.
Same thing happened to me. My machine shop goofed up the first motor, so I had to source another ls1 block. Luckily, the bare ones are only about $200 and aren't that hard to find since they came on a lot of cars.
Good luck.
Same thing happened to me. My machine shop goofed up the first motor, so I had to source another ls1 block. Luckily, the bare ones are only about $200 and aren't that hard to find since they came on a lot of cars.
Good luck.
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Well, I was able to cancel the custom sized piston order. Made a clean trade for an un-bored ls1 block so I will.be going with some good ole off the shelf Diamond 3.905 -8.6cc pistons. Same as I had before so I can't go wrong there.
I had the same problem with my ls6 block and diamond 3.905 pistons... Got a scratch in the cylinder wall that was too deep for a .001 clean up hone so I picked up a 5.3 iron block and I'm getting it bored/honed to 3.905 and reusing my rotating assembly.
Sucks because it has delayed everything but I'm over it now.
Sucks because it has delayed everything but I'm over it now.