Best economy configuration?

lowaltituderecord · Post by **lowaltituderecord** » Sat Sep 27, 2008 8:52 am

Would people mind reporting actual performance (GPH, TAS, range etc.) that they are getting from actual engine configurations in their RV's

Would like to go with a 180hp, but given the price of fuel it looks like 160 is more realistic.

Post by **Spike** » Sun Sep 28, 2008 7:16 am

Hmmm, the fuel burn differences is what? 2GPH? With fuel at $8 per gallon, the hourly flight cost difference is only $16, which you can reduce by throttling back. Overall fuel price will be $84 (10 GPH) vs $69 (8.5PHG). Factoring in engine reserves, insurance, and the build cost (~80K on the low end?) I say if you want the 180, put it in. The difference in operating cost could easily get lost in the overall cost of the venture.

John

cnpeters · Post by **cnpeters** » Mon Sep 29, 2008 2:08 pm

It doesn't matter whether you go with a 180 or 160hp engine. One can get the same fuel burn throttling the 180hp back a bit, unless you have a 'lead hand'. For RV-9 drivers, I have seen the best fuel burn numbers from the minority who have put in a 180hp IO-360 over the Van's recommended max IO-320 160hp, but the difference is slight. With the FI, I am routinely seeing people get 8gph/186mph in either configuration. I am going with the higher 180hp in my -9 since it will give me extra climb performance with a cost saving fixed pitch prop. But, if fuel costs keep worsening, an option exists to throttle back and see numbers like 140mph/5gph, which roughly corresponds to the same mpg as my Acura TL. So, overall I wouldn't worry about the engine hp so much, as a throttled back 180hp has the same thermodynamics as a 160hp. When the time comes for acquiring an engine, perhaps let a deal persuade you one way or the other. If buying new from Aerosport, Mattituck, etc, the cost is about the same.