How much difference in HP does difference size tubes on headers make. I Know different heads is where u start first but, I'm wondering if to big of tube size could kill HP?
Header Size?
- Thread starter sport200
- Start date
Yes. A tube too large will slow exhaust port velocity which in turn will affect low end torque. Most headers available for a 5.0 have a tube diameter of 1-5/8", some stockers only measure 1-1/2". Race engine headers can be 1-3/4, 1-7/8, or even 2" in diameter, ( most of which will not even fit a stock port configuration) and every one of them are a sure fire shortcut to eliminate torque in a street car, especially a mildly modified one.
Bottom line: Stay away from the slightly used C/L listed set of Kooks 1-7/8 LT's for a set of R heads.
^^^ what Mike said. What heads/combo are you looking to do? If stock heads stay with a 1 5/8" shorty(or even keep the stock manifolds). If it's a good h/c/i don't go above 1 3/4(if it's 302-347 based). It all depends on the combination of parts and what you're trying to accomplish.
Awesome Reply Thanks. I have a set of JBA long tubes on my car with a DART ll cast iron head milled to about 50cc . I was just thinking of going with a different header , these are 15 -17 years old. I cant recall the tube size . Ill have to look it up. Thanks again.
This is a blanket statement and not true. You want the correct sized headed for a given application. I had a 1 7/8" header on my old 345" combination that was shifted at 6700rpms, and was fairly mild, there was no noticable torque loss going from a 15/8" to 1 3/4" header to the 1 7/8"
If you are planning on running nitrous you may want to go up one primary size from what the motor wants NA cause you need to get those hot gases out of the chamber as fast as possible, there is not one answer to this question and if you size the header correctly for the combination, you will be headed in the right direction.
It was a blanket statement, because it was a blanket question.
W/O knowing what engine or what the intended use for the op's engine is to be, I doubt that the engine is anything other than stock. And a stock engine will surely suffer from a tube that's too big if its intended use is to be a DD.
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