READ THIShttp://www.rehermorrison.com/techtalk/20.htm
theres EXCEPTIONS but generally.....
the BIG BLOCK HAS
LARGE VALVES=more flow at any lift
MORE EFFICIENT PORTS=more total flow per port
SPLAYED VALVES= better low lift flow/better exhast flow
LESS CYLINDER WALL SHOUDING=due to slightly larger bore on average
LONGER RODS= MORE HIGH RPM DWELL if STROKES EQUAL
LARGER DIA CAM=LESS stress on lifter
LARGER SPRINGS=less pressure needed in some cases
STRONGER BLOCK,=Less distortion under higher pressures
LARGER DIA MAIN CAP BOLTS=STRONGER
MUCH LARGER DISPLACEMENT POTENTIAL.--OBVIOUS
WIDER BORE CENTERS= better cooling
LARGER DIA. BEARINGS=more load capacity
STRONGER PUSH RODS=SBC generally 5/16", BBC 3/8 or 7/16"
EXHAUST PORTS equally spaced=better cooling
getting 500hp from your average 350,383 sbc takes a good deal more effort than from a 427-454BBC
ONCE you exceed about 600hp the BBC combo tends to be CHEAPER at any hp level
http://www.ohiocrank.com/enginekits.html
http://www.ultrastreet.net/
mark iv blocks
mark v blocks
(keep in mind that ALL '91 and later Gen.V and Gen.VI big blocks come with 4-bolt main caps. The two-bolt big blocks are no longer in production
MANY BUT NOT ALL aftermarket head designs have been modified to work on both the early MARK IV 1965-90 and later MARK V & VI blocks 1991-later.)
BTW, , on BIG BLOCKS the oil pumps and oil filter adapters are different due to the block oil filter recess and rear seals being different
GEN 4 or MARK IV
GEN V and VI
AND YEAH! Im fully aware that the SBC can easily have a larger valve IN RELATION to cylinder displacement
but theres PLENTY of BBC heads flowing close to or even well in excess of 400cfm, a few over 500cfm and darn few SBC heads flowing over 310-320 cfm
http://users.erols.com/srweiss/tablehdc.htm#BBChevy
another way to look at this, the most comon stroker for a SBC is a 383, for a BBC its a 496, if each makes 1.25 hp per cubic inch the 383 makes 480hp
the 496 will make 620hp
youll have a hard time making 600hp from a SBC with no power adders for 7K like this crate engine
http://www.dougherbert.com/dhp496chevyb ... th=614_615
or 900HP for 11K
http://www.ohiocrank.com/enginekits.html
like this 620BBC
theres EXCEPTIONS but generally.....
the BIG BLOCK HAS
LARGE VALVES=more flow at any lift
MORE EFFICIENT PORTS=more total flow per port
SPLAYED VALVES= better low lift flow/better exhast flow
LESS CYLINDER WALL SHOUDING=due to slightly larger bore on average
LONGER RODS= MORE HIGH RPM DWELL if STROKES EQUAL
LARGER DIA CAM=LESS stress on lifter
LARGER SPRINGS=less pressure needed in some cases
STRONGER BLOCK,=Less distortion under higher pressures
LARGER DIA MAIN CAP BOLTS=STRONGER
MUCH LARGER DISPLACEMENT POTENTIAL.--OBVIOUS
WIDER BORE CENTERS= better cooling
LARGER DIA. BEARINGS=more load capacity
STRONGER PUSH RODS=SBC generally 5/16", BBC 3/8 or 7/16"
EXHAUST PORTS equally spaced=better cooling
getting 500hp from your average 350,383 sbc takes a good deal more effort than from a 427-454BBC
ONCE you exceed about 600hp the BBC combo tends to be CHEAPER at any hp level
http://www.ohiocrank.com/enginekits.html
http://www.ultrastreet.net/
mark iv blocks
mark v blocks
(keep in mind that ALL '91 and later Gen.V and Gen.VI big blocks come with 4-bolt main caps. The two-bolt big blocks are no longer in production
MANY BUT NOT ALL aftermarket head designs have been modified to work on both the early MARK IV 1965-90 and later MARK V & VI blocks 1991-later.)
BTW, , on BIG BLOCKS the oil pumps and oil filter adapters are different due to the block oil filter recess and rear seals being different
GEN 4 or MARK IV
GEN V and VI
AND YEAH! Im fully aware that the SBC can easily have a larger valve IN RELATION to cylinder displacement
but theres PLENTY of BBC heads flowing close to or even well in excess of 400cfm, a few over 500cfm and darn few SBC heads flowing over 310-320 cfm
http://users.erols.com/srweiss/tablehdc.htm#BBChevy
another way to look at this, the most comon stroker for a SBC is a 383, for a BBC its a 496, if each makes 1.25 hp per cubic inch the 383 makes 480hp
the 496 will make 620hp
youll have a hard time making 600hp from a SBC with no power adders for 7K like this crate engine
http://www.dougherbert.com/dhp496chevyb ... th=614_615
or 900HP for 11K
http://www.ohiocrank.com/enginekits.html
like this 620BBC