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Old 06-09-2014, 01:13 AM   #12
tinydb84
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Join Date: Jul 2009
Location: San Jose Ca
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Re: Building a true 500hp SBC

Quote:
Originally Posted by Super73 View Post

The initial header tube diameter should be as close to exhaust port cross section as possible but not smaller, then be stepped up from there. IE if exhaust port cross section is 1 1/2", start there then grow the tube to 1 5/8 then 1 3/4 before the collector. Exhaust exiting the port is extremely hot and dense, velocity is high. As it cools it expands and velocity slows requiring more room to flow adequately.

Just some thoughts..
I always wondered why they did this with headers. Learned something new today.
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