vocky said:
ideally the primaries and secondaries should be the same length, at a guess 350mm should be ok for each, so 700mm long
Strange as everything I've read implies the secondaries should be half the length of the primaries.
Mind you I've read a stack of yank stuff (and used the 4 stroke tuning books formulas) that says we need small bore (0.75"!!!!!!!!) primaries, but 1.5-2M long lol, and then Mr Valentine (and Winstar) saying the primaries should be 1.75" and about half the length.
Mr V and Winstar definately know what they are talking about, but also the yanks have done loads of testing on the dyno with all their crazy assed designs.
so so so confusing.com/WTF :crazy:
ohh found more info... and it makes sense (ish)
"However, having the ability to use different tube sizes allows much greater flexibility in designing a header. Smaller tubes act like longer tubes, and bigger tubes act like shorter tubes."