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92transamguy 02-03-2013 07:51 PM

Newbie with head questions
 
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:spank:

vinniekq2 02-04-2013 05:51 AM

I would find the nearest/cheapest flow bench in the area. Not sure what your goal is?What would make a street engine perform the way you like it?Im guessing that 350 HP is in order? All of those heads would work up to 350 horse power.all need to be modifies, so use the best ones based on cfm flow and modify as required for fit and freshen. The vortecs,for example need to be clearanced for over 450 ish lift cams.

snakebit68 02-04-2013 08:18 AM

heads
 
The vortec heads have relatively small combustion chambers, which serve to boost compression. I've also been very impressed by their flow numbers. However, Vinnie is right about having to do some work to them because they are limited by their .450 lift capability. A little machining and porting, a good set of springs, and those vortecs will produce a ton of street power. If your goal is a little more devious I might lean toward the camels. Somewhere around here I have stats on flow numbers for just about every head ever made for a small block...factory and aftermarket. Vortecs had monster numbers and impressive flow...but also fell flat on their face after a certain amount of lift. Hope this will help a little

oldbogie 02-04-2013 04:34 PM

Quote:

Originally Posted by 92transamguy (Post 1642318)
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:spank:

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

snakebit68 02-04-2013 05:24 PM

heads
 
Yeah Bogie, Thats kinda what I was trying to say about the Vortec heads. If used with a less radical cam they will blow the camels away perfomance wise. Large lift cams dont do well with the Vortecs stock spring capabilities. That is all I would alter on a vortec...machine the spring seats to accept a larger, stiffer spring and they will accomodate a large lift cam. However, flow numbers start to drop off over .500 and completely crash anywhere near .600. So, if used in a race application I'd go with heavily ported camels...but on the street for great performance, the vortec's are unriveled when it comes to bang for your buck.

92transamguy 02-04-2013 06:32 PM

yea im looking to be weekend cruiser that can make a track pass if i want to,,i have the option of heads i didnt know around what cc the vortecs were compared to the others ,i did read you can get beehive z28 springs and install on vortecs and they can go with bigger cam then,,my dad is oldschool and swears by the doubles but i try to tell him i read the vortecs are way better ,, only staying with the cam cause i came with my motor so figured why waste it..


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