Big block generations
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Joined: Feb 2004
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From: Ravenna Ohio
Big block generations
4, 5, or 6. Which gen is best to build a 600 RWHP naturally aspirated street machine. From what i've read gen 5 isn't looking too good. It seem like things were changed back to match the old block with the gen 6. So which one would you guys use.
Thanks Josh
Thanks Josh
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Joined: Mar 2001
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From: Living in the Hartland
Originally Posted by JDRez42
4, 5, or 6. Which gen is best to build a 600 RWHP naturally aspirated street machine. From what i've read gen 5 isn't looking too good. It seem like things were changed back to match the old block with the gen 6. So which one would you guys use.
Thanks Josh
Thanks Josh
Team Owner
Joined: Feb 1999
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From: Republic of Texas
I'd go w/ the Gen VI it at all possible. The Gen IV's have 2 pieces rear oil seals and have adjustavble valvetrains. The Gen V have 1 piece seals, non-adjustable valvetrain, but has no mech. fuel pump boss. I'm pretty sure the Gen VI has the 1 piece seals, non adjustable valvetrain and mech. fuel pump boss.
All were availible w/ 2 bolt or 4bolt mains. To acheive 600RWHP or (700hp+ at the crank) N/A you'd have to have a nice set of aftermarket heads, probably stroked to a 496ci, 11:1+ compression and a fairly agressive cam. Power can be made with less compression and ported heads, but at the expense of a radical cam. The motor wouldn't be street friendly but that is a realative term. If I were looking for 700hp+ natuarlly aspirated BB I wouldn't even consider a stock block. I'd go with a Dart or Motown and stroke it to a 540ci+ which would make it that much more drivable and have that much more potenial.
Then again I could care less about being N/A. As they say, "I'd rather be blown than stroked." :p
All were availible w/ 2 bolt or 4bolt mains. To acheive 600RWHP or (700hp+ at the crank) N/A you'd have to have a nice set of aftermarket heads, probably stroked to a 496ci, 11:1+ compression and a fairly agressive cam. Power can be made with less compression and ported heads, but at the expense of a radical cam. The motor wouldn't be street friendly but that is a realative term. If I were looking for 700hp+ natuarlly aspirated BB I wouldn't even consider a stock block. I'd go with a Dart or Motown and stroke it to a 540ci+ which would make it that much more drivable and have that much more potenial.
Then again I could care less about being N/A. As they say, "I'd rather be blown than stroked." :p
Race Director
Joined: Sep 1999
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From: Plano TX
I think he's talking about engine generations (Mark IV, Gen 5 and Gen 6), not Corvette generation...
Any of them can support the power when built right. Gen V has some incompatabilities with other generation cylinder heads so you probably want a Mark IV or Gen 6. My choice would be whichever of the Mark IV and Gen 6 I found at the best price. Gen 6 will cost more to build as far as crankshaft due to the one-piece rear seal making it incompatible with Mark IV cranks. Maybe someone makes an adapter to run older cranks? Dunno.
Any of them can support the power when built right. Gen V has some incompatabilities with other generation cylinder heads so you probably want a Mark IV or Gen 6. My choice would be whichever of the Mark IV and Gen 6 I found at the best price. Gen 6 will cost more to build as far as crankshaft due to the one-piece rear seal making it incompatible with Mark IV cranks. Maybe someone makes an adapter to run older cranks? Dunno.
Pro
Joined: Mar 2002
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From: St. Louis MO
There is an adapter to convert back to the 2 piece rear main. The only drawback to the Gen 6 block is that you can only go .060 over according to any of the books i have read so if you want a really big bore your going to need a 502 block with the 4.5" bore compared to the 454 block which is 4.25". The nice thing about the gen 6 block is that you can use a factory style roller lifter and lifter retention spider. You won't break one of those dog bones and have a roller lifter turn on its side chewing up your cam from link bar failure. Some of the parts are a little more expensive, like aftermarket timing chains, but Comp Cams isn't the only one that offers adjustable replacement chains for them anymore. You can install mark 4 heads on a gen 6, I have done it successfully. The gen 6 blocks from a fuel injected truck will not have a mech fuel pump boss, but some of the service replacement blocks from gm might come with that part drilled out. The mech clutch linkage boss I blieve is also missing on the truck blocks but may be on the service replacement blocks.
