Frankly I'd be more worried about the internals staying together. N/A not so much but 20-30psi I'd be concerned. 
Opinion Requested: 454 vs 427
I don't think you can go bigger than a 4.125" bore with any block right now. That's the biggest bore I was told that could be done. That was with the 6.2L block. The 6.0 and 5.3 blocks would have smaller max bores. Basically, you can only get OEM-sized dry sleeves right now. Supposedly, Darton has a dry sleeve for the 6.2L that can go out to 4.125". At least, that's what I was told by the machine shop that talked to Darton.
I found some 6.0L and 6.2L blocks for $200 in Austin. I don't know how bad the damage is, but I was going to go look when I get time. It costs $200 per cylinder for dry sleeves. So, about $1,800.00 for a block, potentially with a 4.125" bore. That's way cheaper than any other option out there. I haven't even seen an LS7 block for sale in years.
I found some 6.0L and 6.2L blocks for $200 in Austin. I don't know how bad the damage is, but I was going to go look when I get time. It costs $200 per cylinder for dry sleeves. So, about $1,800.00 for a block, potentially with a 4.125" bore. That's way cheaper than any other option out there. I haven't even seen an LS7 block for sale in years.
Only guy I trust for sleeving. He’s done several for me.
Staging Lane
Joined: May 2017
Posts: 54
Likes: 5
With the expense of sleeving and all the other machine work involved, would be better in the long run to just buy an LSX454 bare block with a 4.185 bore? New block less than double the cost of all the machine work and a bigger bore to boot. The LSX block comes honed ready to go, but of course double checking is prudent. Cast iron might be a concern.
ERL did really nice work. Looks like your motor will be a beast. However, imho, pistons with such little skirt area are bound to rock. That said, the Diamond pistons in my LS7 are no shining star in that department, either. Its not just Diamond, either. There isn't much any piston manufacturer can do with the deck height being what it is, combined with a 4.00", or longer stroke. But hey, we know when we build them it's not going to be installed in the family sedan, and go for 200,000 miles. It's not your Grandpa's 454, with 275hp!!! That is one place that favors the original 427 big block, and that's the 3.75" stroke. Oh well. I know my pockets aren't deep enough to do it, but I know there are people out there that could do this. "This" being a C5/C6/4th & 5th gen Camaro/4th gen Firebird with the ZL1 big block in place. I've never seen one, especially a C5 or C6, though there are probably a few out there.........Somewhere..........
I don't think you can go bigger than a 4.125" bore with any block right now. That's the biggest bore I was told that could be done. That was with the 6.2L block. The 6.0 and 5.3 blocks would have smaller max bores. Basically, you can only get OEM-sized dry sleeves right now. Supposedly, Darton has a dry sleeve for the 6.2L that can go out to 4.125". At least, that's what I was told by the machine shop that talked to Darton.
I found some 6.0L and 6.2L blocks for $200 in Austin. I don't know how bad the damage is, but I was going to go look when I get time. It costs $200 per cylinder for dry sleeves. So, about $1,800.00 for a block, potentially with a 4.125" bore. That's way cheaper than any other option out there. I haven't even seen an LS7 block for sale in years.
I found some 6.0L and 6.2L blocks for $200 in Austin. I don't know how bad the damage is, but I was going to go look when I get time. It costs $200 per cylinder for dry sleeves. So, about $1,800.00 for a block, potentially with a 4.125" bore. That's way cheaper than any other option out there. I haven't even seen an LS7 block for sale in years.
Thread Starter
12 Second Club
Joined: Dec 2017
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From: San Antonio
....and then the fight started.
Staging Lane
Joined: May 2017
Posts: 54
Likes: 5
Junk Iron? Really? Cast iron can handle more NOS or boost than any aluminum block. I'm sure when you have 1000 HP that extra 100 pounds of junk is really gonna matter!
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Originally Posted by Utinator
That sounds awesome! Was it done recently?
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Thread Starter
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From: San Antonio
A lot has changed since then. I don't think you can build that engine today. I'll keep an eye out for a 6.2L block. If I can find a rebuild-able block for cheap, I'll grab it, but I'm not getting in any hurry to build another engine until I build a garage. I need a place to work first. I have been using my dad's shop, but it's not close.
Thread Starter
12 Second Club
Joined: Dec 2017
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From: San Antonio
I'm just messing with you. I know that iron blocks are stronger. I just don't want the extra weight in my car. You can't use that much hp on the street anyway. 
TECH Apprentice
Joined: Jul 2020
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I will disagree. I could definitely feel the front end weight difference with doing a LSA style blower and all the extra components on my LS3 C6. Probably more so in a C6 as it was only a 3,180 lb but it added over 90 lbs to the nose and though it wasn't terrible it was noticable.
Last edited by 440_Stroker; Jun 7, 2022 at 12:43 PM.
