Quote:
Originally posted by mattr762
Excuse my noobness, but why did you gain TQ with the 3" headers vs the 4"?
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The boat headers had relatively short primaries and big 4" collectors.
From the testing I did I came to the conclusion that to a certain extent, the primary pipe and collector size is more a factor of RPM than it is engine size or horsepower levels.
The smallish cam (for the size of the engine) made all of it's power by 6000 rpm, which is what I was shooting for, a good street engine. A 1-3/4 or 1-7/8 primary pipe size is all this engine needs to make good horespower and torque. If the engine were to turn 7500 rpm, the cam, and then the headers would need to be bigger.
In the same turn, this is why tri-y headers are so good for mild street cars and trucks.
It all depends on what you are asking of your combination.
--Mike