Chevy 350 Twin Turbo Question?

[myclone]

In the near future I'm planning on building a twin turbo small block Chev for a 1987 Buick Regal. Now for the questions. I need to know if a good old regular Chev 350 4 bolt main will work for this kind of power or do I need to run an aftermarket block? Next, once I have the block what do I use for internals to withstand this kind of power. I'm looking upwards of about 800 horse. Any advice would be greatly appreciated.

There are probably as many opinions on the above as there are ways to build a SBC and so far everyone has provided sound advise IMO. I'll throw my .02 in the mix FWIW since Ive seen some turbo motors disassembled that were using some of the components you mentioned.

An early 90s production cast cranked (crank cryo treated), Eagle H beam rods, two bolt main block with ARP main studs and nodular iron main caps had signs of main cap movement at the 600hp mark. This was on fairly low boost of 15psi and a good tune (no detonation to speak of).

The same block was remachined for production style four bolt mains, reassembled, and was on the way to 800hp when a cracked cyl wall stopped the dyno pull. The block was sonic checked before boring (.030 over) but IMO there was a casting flaw that propogated the crack which sonic checking wouldnt have shown. Anyways, upon disassembly the mains didnt show any evidence of movement but then again the motor wasnt leaned on for very long before the crack in the cyl developed.

Next was a late 80s (89 I think) production block that was machined for splayed four bolt mains and the main caps were from Program Engineering. The rotating assembly was transferred from the above engine to this block and it made 920+hp and just under 800ft/lbs on the dyno without so much as a whimper and is going strong in a street car as we speak. Could it scatter tomorrow? I guess it could but we leaned on it harder than it will ever be when it was on the dyno and upon disassebly to assess any wear the rotating assembly and bearings looked good as new.

An aftermarket block is the way to go for piece of mind if you dont have any issues with the added cost but then again those pieces are of superior quality and will prolly last a life time at your 800hp goal with a good tune. A production block is deffinately cheaper but you may go through a hand full of cores to find a good one which isnt free unless you own a machine shop and once you do find a "good" one there is still the possibility it could scatter all over the dyno room.

To sum it up a production block is a capable piece with some work and some expense that wont break the budget but an after market block, while more expensive up front, is one of those deals where you can just about abuse it as much as you want without crossing your fingers that you wont carry it home in a five gallon bucket.