blacktop ramtubes....wot length?

[phatman3801]

im wanting to get some of those ramtubes for my blacktop im looking at the ones "tony miller" is selling, the thing is that would be the best length to get for a blacktop??? he makes them in length up to 70mm, now i have done a seach on this but cant find any info about would would be the best length trumpets to use

[Mr Revhead]

bet you can
and the answer is......


leave them alone

[phatman3801]

well lets say i dont leave them alone lol then what would be the best length to use

[Mr Revhead]

that would all depend on your mods and where you want the power.

go have a look at redmists sig

[RedMist]

The Helmholtz calculations are quite complex. If your enigne runs standard cams at standard timing and doesnt have any other head modifications I would stick with the factory length, which is considerably more than 70mm.
Other than that your pushing the Helmholtz frequency further up the rev range, possibly to a point you just cant use.
General rule of thumb is to use Helmholtz to increase your torque range by placing it at the bottom of your usable RPM range.

[Mr Revhead]

and i beleive longer runners AFTER the t/b is better for low down torque... longer in front of the t/b for top end power