mtngun
Addicted to ArboristSite
K, taking up where we left off ......
.... exhaust port widened from 28.1 to 29 mm (arc, not chord).
.... intake port widened from 25 to 27 mm
.... transfer ducts hogged out an additional 1mm each
.... upper transfers widened 1mm each
.... muffler matched to exhaust flange
.... still at 0.025" squish, 162 intake duration, 160 exhaust, 26 blowdown.
In other words, a mild woods port.
Red line is where we left off in the previous post.
Blue line is the mild woods port.
Well, widening the ports didn't do much, at least not with these timing #'s.
I did experiment with blowdowns ranging from 22 to 28, but 26 seem to be optimal at sane RPM's.
I have yet to try bumping the exhaust up more to say, 165 degrees duration.
I may be able to get more diameter out of the transfer ducts, the 1mm number was just a guess. Likewise, perhaps another mm out of the intake and exhaust, but so far haven't seen a reason to do so.
.... exhaust port widened from 28.1 to 29 mm (arc, not chord).
.... intake port widened from 25 to 27 mm
.... transfer ducts hogged out an additional 1mm each
.... upper transfers widened 1mm each
.... muffler matched to exhaust flange
.... still at 0.025" squish, 162 intake duration, 160 exhaust, 26 blowdown.
In other words, a mild woods port.
Red line is where we left off in the previous post.
Blue line is the mild woods port.
Well, widening the ports didn't do much, at least not with these timing #'s.
I did experiment with blowdowns ranging from 22 to 28, but 26 seem to be optimal at sane RPM's.
I have yet to try bumping the exhaust up more to say, 165 degrees duration.
I may be able to get more diameter out of the transfer ducts, the 1mm number was just a guess. Likewise, perhaps another mm out of the intake and exhaust, but so far haven't seen a reason to do so.