Originally Posted by
Cougar429
SrTelemaster150, I agree with a lot of what you stated regarding bore size/HP, but there are many other factors that will affect your power output beyond just that measurement.
Volumetric efficiency is a calculative value and does not always play by the numbers. Even if you ignore environment, in the end valve size, orientation, overlap and timing/RPM will have a major roll in how the engine breathes. Same with intake and exhaust size and length and if they are tuned to work best at the specific RPM you need.
I was speaking in generalities, all other factors being equal.
But, since you mentioned valve size, the FA-115 uses the lager FA-125 valves, the FA-100 has its own part # so I would assume that they are smaller which would be likely since the bore is only .8mm larger than the FA-91 while the FA-115 bore is 2.7mm larger than the FA-100.
The cams, rockers & tappets are identical, right down to the part # & Saito engines are pretty consistent when comparing the orientation of the valves.
All that being said, yes, the FA-115 would, in all probability, achieve better volumetric efficiency compared to the FA-100, & I would bet that it would produce more TQ than the FA-100 at any RPM range that would be suitable in an aircraft application.