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Old 06-15-2009, 12:47 PM
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Building Headers, Exhaust port exit angle question

As the title says, building 304 tubular headers for 97 Pontiac turbo v6 (not GN motor) converted from FWD to RWD

I was looking at the usual:

Courtesy of standard abrasives
As you can see the exhaust port exits the head perpendicular to the flange mating surface

However on the ported heads I am using for my project (Iron heads on the right):

Courtesy of zzperformance
The exhaust ports exit at an angle of about 22 degrees from the flange mating surface.

I was thinking that it would be beneficial to exhaust flow if the primaries were welded to the flange at the same angle as the the exhaust runners so there would not be a sudden sharp turn right at the transition.

My question to everyone here is is my logic sound or is there a veriable I am missing here ie: the exit angle is there to prevent exhaust reversion etc

I have plenty of room in the engine compartment (best pic I have on hand)

I think its about a foot on either side

Thanks for the help

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Old 06-15-2009, 10:44 PM
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Interesting project you have there.

Your thinking is sound, it is beneficial to maintain the exit angle of the exhaust port, and seeing that you have room for it, why not? I would assume that anything that salvages as much heat and velocity from the port is good for the turbo.

My guess is that the factory created that exit angle in the interests of efficiency, it is straighter than the 90 degree bend in 'exhibit A'.
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