Posted by RDavis on Wednesday, July 16, 2003 at 9:45PM :
Why does there seem to be 2 trains of thought on the definition of the term,
Tuned Headers ?
Some swear it has something to do with the need for backpressure and some swear it has to do with negative backpressure or a scavenging suction. All my older automotive theory books say an exhaust system should be as straight and freeflowing as possible, eliminating as much back pressure as possible so the cylinders can empty the exhaust gases as quickly and completely as possible.
Yet some have adimently insisted that a engine exhaust system needs back pressure which would seem to defeat the books explaination and reason for as much negative back pressure as possible.
My question is, does the term tuned exhaust mean that headers are designed so that exhaust gases positioned to pass the upcoming exhausting cylinder , will cause a scavenging suction to help pull the exhaust gases from that cylinder more completely so as to aid in a better intake charge,increasing the engines volumetric efficientcy or,
does an engine really need back pressure and why?
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