Dr.Ben
rrProfessor
Location: Richmond, VA, USA
My Posts This: Topic Forum | You're going to need to compromise a little here. If the gear ratios you have avaiable are 7.9 and 8.27 (and 8.45 is no good for this engine, BTW), your best bet is going to be to lower your headspeed to yield an engine rpm of about 15-15.2K or less. 8.18 has historically been proven to put this engine in about the right place rpm wise at under 1850. You can use that ratio to see how I have extrapolated the rpm range for you based on your available gearing.
8.27 works well for the SZ and HZ at 1850+, but the C-Spec is not ported to make power at these rpms. In addition, exhausts such as the SB-17 and MPII which were designed for the C-Spec will not produce the best power at these high rpms either.
7.9 will put the engine in the right rpm range for a head speed of 1900 and even more, but you'll lose the ability to maintain that headspeed in hard, tight 3D because the gearing is tall as compared to the 8.27 and costs the engine the gearing advantage to pull under heavy load. Thus it would be my suggestion to lower your headspeed just a bit to get the engine into the best powerband and then learn to fly the model around that set up. And look for a good deal on an HZ  .
Ben Minor
Representing
MRC Hirobo Helicopters and Team Futaba for Radios
Morgan Fuels
OS Engines |
