Ed, My thinking is that there may be a small increase in fuel consumption, but not much. First, the O-200 rorating assembly is stroked, so it is a 201 c.i.d. vs. a 188 c.i.d. The engine is not working as hard as a C-85 at the same RPM; it's putting out more torque than a C-85 at the same RPM. Second, it's higher compression. Third, the O-200 recommended 75% cruise speed is 2500 RPM, so I would expect that whatever the O-200 fuel economy is, I would see the same. The only thing I haven't accounted for is the different cam profile between the C-85 and O-200. I will be keeping the C-85 cam as far as I know. So any increase in fuel consumtion should be from the increase in parasite drag, and from the greater displacement engine; kind of the same way that the 6.0 liter LS-2 engine uses more fuel than the 5.7 liter LS-1. (I think!)
Dave --- In [email protected], "Ed Burkhead" <e...@...> wrote: > > > Dave wrote: > > I'm getting 107.95 at 2500 RPM with a 7148. > > That's with the 5% loss. Certainly seems > > realistic for the C-85/O-200 STC engine. > > > Right > > Flying at 2500rpm instead of 2400rpm, gets you almost four extra mph. > > I'd also want to figure the increase in fuel consumption. If extra speed > makes you do an extra fuel stop, you've lost all advantage of the greater > speed. > > In many cross country flights, I've increased my total speed by slowing down > to 90 or 85 or so and, by getting better fuel economy, I've been able to > safely bypass a fuel stop. > > Taking all this into account adds to the mental > brain-all-involved-and-active aspect of flying that I love. > > Ed >
