How much bore is to much?
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How much bore is to much? Hi guys. I was wondering if i could get away with a 3.903 bore in my 4.8 LS block and still reliably run boost without blowing out the cylinder walls? The motor retains the stock crank and i have forged rods in hand for it. Just trying to decided on piston bore before i give the machinst the ok. Planning on turbos and around 8-900hp crank. I dont plan on turning it up in the future.
Hi guys. I was wondering if i could get away with a 3.903 bore in my 4.8 LS block and still reliably run boost without blowing out the cylinder walls? The motor retains the stock crank and i have forged rods in hand for it. Just trying to decided on piston bore before i give the machinst the ok. Planning on turbos and around 8-900hp crank. I dont plan on turning it up in the future.
That said if your gonna do it, do you really need to go to 3.9"? Are pistons just that much cheaper? OR can you run go say .060 over for the same cost? Are you going to run the 5.3 crank and rods?
Just for comparison i'm going 8.80's at 158 on a mild 4.8 S480 combo. Untouched short block.
Last edited by Forcefed86; Jul 21, 2020 at 08:27 AM.
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Lots have done it. But not all blocks are created equally. They *should* be sonic checked when you go that big. But when your talking $300 long blocks I question if that's cost effective or necessary. IMO you don't need the bigger bore to make your power goals, So I don't see the reason to bore it out that big personally. Machining a 4.8 at all for those goals seems counter productive. For the cost of a machine shop visit and forged internals you could just buy gen 4 4.8... possibly 2 or 3. They will handle 900 crank "as is".
That said if your gonna do it, do you really need to go to 3.9"? Are pistons just that much cheaper? OR can you run go say .060 over for the same cost? Are you going to run the 5.3 crank and rods?
Just for comparison i'm going 8.80's at 158 on a mild 4.8 S480 combo. Untouched short block.
That said if your gonna do it, do you really need to go to 3.9"? Are pistons just that much cheaper? OR can you run go say .060 over for the same cost? Are you going to run the 5.3 crank and rods?
Just for comparison i'm going 8.80's at 158 on a mild 4.8 S480 combo. Untouched short block.
And it does have to be a GEN4 internals 2005+ engine. The older engines had wimpy rods. If its apart and at a machine shop. Source some stock gen4 5.3 internals (crank/rods/pistons) and drop them in. Or just nuy a 5.3! lol. engines are the cheap parts!
Forcefed86 steer'd OP in the right direction but my question to OP's would be "Are we talking daily driven engine or racing engine?"
A machined block with engine block filler could probably handle some abuse.
A machined block with engine block filler could probably handle some abuse.
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I agree! And depending on the application a 3.9" bore may be desirable. I was looking at doing the same for a high compression NA build and wanted the cubic inches as cheaply as possible. 3.9" bore hyper pistons are pretty darn cheap, so that was my reasoning.
But a 900hp turbo build isn't anything to sneeze at... I'd want the block as strong as possible if doing that. No to mention time/money wise you're just better off cycling $300-500 short blocks as necessary IMO. Build everything in mind of quick/easy disassembly. Forged or not... crap always goes wrong. And if your waiting on machine shops constantly it gets old fast. I'd rigid mount the turbo and plumbing in a way that you could literally leave most of it installed when putting engine in/out. Same with the cooling system and wiring. Going on my 4th season with this 8 second "temporary" $500 4.8 I threw in to get me by. Have a spare alum 5.3 sitting here waiting. Jus tpick up deals when they pop up and have a spare... or two!
But a 900hp turbo build isn't anything to sneeze at... I'd want the block as strong as possible if doing that. No to mention time/money wise you're just better off cycling $300-500 short blocks as necessary IMO. Build everything in mind of quick/easy disassembly. Forged or not... crap always goes wrong. And if your waiting on machine shops constantly it gets old fast. I'd rigid mount the turbo and plumbing in a way that you could literally leave most of it installed when putting engine in/out. Same with the cooling system and wiring. Going on my 4th season with this 8 second "temporary" $500 4.8 I threw in to get me by. Have a spare alum 5.3 sitting here waiting. Jus tpick up deals when they pop up and have a spare... or two!
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