350 SBC 4 Bolt Main 800 to 1000 HP

[kenny_bandit]

its a guy her in town whos building a turbo vega whit a blazer 2bolt 350 engine and a holset hx80 his sighting for about 650++ hears the site but its in swedish http://forum.savarturbo.se/viewtopic.php?t=6232

and a nother http://forum.savarturbo.se/viewtopic...r=asc&start=15
and a site from him in english http://aldengard.lixom.nu/gallery/Tw...ransAm_Project

[MonzaRacer]

I would sell the 4 bolt to a local hot rodder or store it and get a 2 bolt main older style block with large pad under the alternator(mid early 70s) and then add on a set of splayed bolt main caps this setup WILL handle 1000+. A factory 4bolt even with lots of reinforcement in my honest opinion as an engine builder and tuneer around 700 to 800 and thats NA.
The stresses created on a turbocharged engine is so quick in their rise they can and will split the blocks if not done right.
If you are on the budget honsetly after all the machine work you can step up to a fresh World Products block and all you have to do on those is clean the thing finish bore/hone to size ,,, maybe set your deck height and your ready to assemble. considering how cheap Eagle has rotating assemblies you can get great parts a decnt price and if you dont beat on it too hard a stock GM crank properly preped will live under just about any use. I am lucky I have a local crank grinder that does lots of cranks the week of the NAtionals at Indy every year. just remember its better to spend more on your rods/pistons and then save for heads THEN get it running that to build it, blow it and then cry over not spending money. Dont gt me wrong I am not saying you need a 3000 dollar crank and titanium rods just dont skimp on the rods, Eagle, Crower, Oliver are some good names and use reputable pistons as some forged units are to fragile in turbo setups (or any boost for that matter )and can shatter. The rule is use a piston that can be set tighter (but still forged) clearances but allow for more heat.
Good Luck and if you have any questions on machine work give me a shout.
Lee Abel

[Thrillrr]

check over on turbomustangs.com they have a lot of guys over there running turbo vehicles besides mustangs, that can help you out.

[64duece]

Ditto on much of the above. I've done both 4 bolt and splayed 2 bolt conversions on blown 355's.

First setups were blown w/ Procharger's D1. The first one showed moderate bearing wear after one season of street driving/racing. Approx 700hp w/ 14lbs on pump gas.

We then switched to the 2-bolt splayed cap block and noticed the improvment. They looked slightly better but enough to keep an eye on them. We upped the power to 850hp @ 19lbs but wouldn't push it beyond that.

When I swapped to a turbo (98mm Precision), we swapped it for the Motown Race block. We worked that deal pretty hard (28lbs) and 1600+hp. Never any signs of abnormal wear.

To make 1000hp, that's really territory for an aftermarket block. The reliability isn't there on GM blocks, sonic checked or not. One may live well at 850hp and another can develop cranks in the mains, or valley area. I've seen and done it. If you keep it limited to 800hp, I would say it's OK. Be aware, you'll likely be $1000+ to make that factory block right w/ steel caps, it's OK if you understand it has limits.

[wildbuncher]

I would sell the 4 bolt to a local hot rodder or store it and get a 2 bolt main older style block with large pad under the alternator(mid early 70s) and then add on a set of splayed bolt main caps this setup WILL handle 1000+. A factory 4bolt even with lots of reinforcement in my honest opinion as an engine builder and tuneer around 700 to 800 and thats NA.
The stresses created on a turbocharged engine is so quick in their rise they can and will split the blocks if not done right.
If you are on the budget honsetly after all the machine work you can step up to a fresh World Products block and all you have to do on those is clean the thing finish bore/hone to size ,,, maybe set your deck height and your ready to assemble. considering how cheap Eagle has rotating assemblies you can get great parts a decnt price and if you dont beat on it too hard a stock GM crank properly preped will live under just about any use. I am lucky I have a local crank grinder that does lots of cranks the week of the NAtionals at Indy every year. just remember its better to spend more on your rods/pistons and then save for heads THEN get it running that to build it, blow it and then cry over not spending money. Dont gt me wrong I am not saying you need a 3000 dollar crank and titanium rods just dont skimp on the rods, Eagle, Crower, Oliver are some good names and use reputable pistons as some forged units are to fragile in turbo setups (or any boost for that matter )and can shatter. The rule is use a piston that can be set tighter (but still forged) clearances but allow for more heat.
Good Luck and if you have any questions on machine work give me a shout.
Lee Abel

2 bolt mains with a stud kit is all I had with a blower and it was making 800hp with a toploader and I never had any problems car ran flat 10s. I think all you 4 bolter spladed billet main caps guys are doing a bit of overkill. Standard 4 bolt mains are plenty mate.