ORIGINAL: david92692
f2racer,
Thanks for the rpm numbers that you are getting. Those sound more in line with what I was thinking. When you say the throttle response is better with an 11.5x4, does that mean the response is not good with the 12.25x3.75? Also, do you notice any mixture issues at low to upper-mid throttle with these engines?
No throttle response if OK with the 12.25x3.75, probably about the same as a good running TT Pro-46 with an 10x5 prop. But with an 11.5x4 response is instantaneous. Much easier to hold a hover exactly where you want when the response is so crisp. Haven't had any mixure problems with either engine. Do buy 2 headers if you get the MVVS, as the length will need to be "tuned" some. The stock header is a little too long for optimal performance. By cutting 1/8" or so at a time (until you reach peak rpms), you'll pick up anywhere from 300-1000 rpm.