peanut port BBC vs VORTEC heads on a sbc

[grumpyvette]

I recently had what I thought was a rather brief but enlightening discussion with a guy that wanted to me to replace his current BBC 454 suburban engine with a 400 built with vortec heads (to get this "increase the low and mid rpm torque while increasing mileage" )the truth is that a mildly reworked peanut port big block cylinder heads (especially with a decent intake manifold and headers) easily out flows a similar vortec head and the bbc engine larger valves and splayed valve derangement plus the larger and stronger components of the big block engine will generally easily produce much better torque in the low and mid rpm range than a similar larger displacement SBC with vortec heads, the main reason that some big blocks don,t produce impressive torque is they generally have lower compression and cam timing thats been more designed to pass emissions than produce power. given a decent 9.5:1 compression on BOTH engines, and gearing each to maximize torque in the rpm range where ech engine can both get decent mileage and be responsive the big block tends to make better power and get similar mileage
spin a 400sbc at 3500rpm and your burning almost exactly the same fuel as a 454 spinning at 3100rpm , if both produce about 1.1 ft lbs the 454 should produce 294hp just like the 400 vortec at the slightly higher rpm, and both should get nearly identical mileage, but the bbc tends to be more durable. while its true the bbc engine weights about 100 lbs more the difference is almost insignificant in a 3800-4200 lb truck especially towing a heavy trailer.

read thru these threads

viewtopic.php?f=69&t=2900&p=7532&hilit=+vortec+heads#p7532

viewtopic.php?f=55&t=624&p=11125&hilit=flow+numbers#p11125

viewtopic.php?f=52&t=322&p=9895&hilit=+flow+numbers#p9895

http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/