Runner Length

[vector1]

in addition

the stack height is measured from the head mounting surface to the first abrupt enlargement--plenum, open to atmosphere.

checked a few numbers and here is what i came up with using 1.75" bore, 2.05" bore would be down in power

11.75" pk tq 569@4500
12.25" pk hp 514@5500
14.25" avg tq 429
11.25" avg hp 325

after looking at the graph with pk numbers, there is a wave that moves with each .5" increment change in stack length along the peak of the curves. successive waves i might add, these are not small either. if the length is held to a max of 9.75 there is no wave, although the peak and avg numbers are lower. this might account for flat spots or lean/rich problems guys are having at certain rpm's.

i'll play with the numbers again at 2.05" throttle diameter and if the numbers are significantly different i'll let you know.

hth

let me know what your exact length is at present and i can let you know what 1" shorter will do.