HEADER DESIGN COMMENTS - Common Mistakes.
Over the years we have seen that people make many, MANY mistakes involving headers. Mistakes are made due to many things - lack of common sense (or bad application of "common sense" because it is based on misunderstandings or assumptions), bad or inappropriate information or advice, decisions made on minimal information, ignorance, attitude (apathy), not willing to spend the money to do it right, etc. Here are JUST A FEW of the mistakes or assumptions we witness or hear about almost every day:
Bigger is better. This is absolutely the most committed mistake we see in headers - people buying headers TOO big - bigger than what is necessary for the engine to produce maximum performance and, because of that, reducing bottom end and mid-range power in the process. Depending how much oversize the header is, top end (peak) power can even be reduced! The only thing guaranteed when going to a larger header is reduced bottom end and mid-range performance.
Headers are NOT important.
ANY header is better than a manifold.
A more expensive header is a better header.
Header tube size is supposed to match the cylinder head's exhaust port size.
That there is one "correct" header tube size for certain engines. (455 Buick engine swap example.)
Equal Length is not important.
"GOOD" headers are not important for street use.
Confusion between Inside Diameter and Outside Diameters of Tubing.
Porting to match a gasket when porting should REALLY be done to match the ports in the header.
When should an exhaust port be left UNported?
HEADER DESIGN COMMENTS