my friend from high school (he races cars and has his own 69 camaro 454 which smokes new cobras like its job) was telling me about the headers i bought and how they'd get me better gas mileage? is this true? would it be the same with my electronic dump valve? thanks guys
-brian

 

Typically, headers increase air (exhaust) flow, increasing efficiency, thereby increasing mpg.

 

I dont disagree... however, I do believe that would apply on higher power use of the specific engine in question. What I mean by that is, if you really want to try hard to get lower milage, usually that would mean careful driving, as thats what offsets milage the most. Now if you do that, and seldom get your engine up in rpm's, then you'd want your car to be optimised for that driving style. And with smaller exhaust ports, you'd get greater exhaust gas velocity at low engine speeds, and hence improve your milage with that style of driving.


However, If you do alot of full throttle driving, headers might very well improve milage for that driving style. As that would improve exhaust gas velocity at high engine rpms where it is restricted in stock configuration.

 

I have Long tubes and a 4" exhaust and

Small if you are a cruiser and big (like me) if it is a car you romp on.

 

I easily agree with larger vs smaller tubes and tuning to the powerband. though going from stock manifold to header with the same primary size and collector sizing gas mileage would go up as it is more free to breath putting less of a srestriction on the motor.