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Old 02-04-2013, 04:34 PM
oldbogie oldbogie is offline
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Originally Posted by 92transamguy View Post
Ok hello my first post here except to introduce myself please dont be to hard,,i have a 92 trans am and it has a 5.7 crate engine with vortecs on it,,and i got my hands on a 74 corvette 350 rebuilt with set of vette double humps that have been made to 202 valves that were under cut unshrouded and ported,,,and i also have a set of heads with 202,s as well,,,, and a set of vortec heads i could use whats your opinion on heads to go with,, my 350 is 40 over with 292 cam with 488 lift for street fun use not daily driving,,thanks for any opinion
Vortec, it takes a professionally ported double hump to get even close to what an out of the box set of Vortecs will do. A lot more to getting power out of heads than what port flow numbers and valve diameters tell you. It takes a highly efficient combustion chamber which the Vortecs have big time. The chamber differences are subtle compared to double humps but these differences have major impacts on performance. These changes speed the burn making it a lot easier to place maximum cylinder pressure in time with where it has maximum effect on the crank angles. This lets you get more compression without detonation and does it on less advance so there aren't forces being wasted trying to push the piston back from where it just came. A stark evidence of the efficiency of getting the power at the right moment in crank degrees comes from the small amount of spark advance needed to maximize power output. The Vortec is happy with 34-36 degrees total where the camel humps want 10 more for less power output.

A 292 cam really needs a pile of compression, this is a very rampy cam. Long ramps bleed compression pressure, unless class rules dicate it; it's a cam I stay away from especially for the street. Faster ramp cams like the Comp Extreme Energy and Lunati's Voodoo pump out more power on fewer degrees because they don't bleed the damn compression to death waiting for the intake to close. But they are quirky with lobe and lifter wear using new oils; they do need proper break in and a steady diet of ZDDP additive.

Bogie
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