Best settings for MPG?

[N8632Y]

To anyone who likes numbers:
Went out today and played w/ rpm settings and MPG (miles per gallon) as found on my JPI 760 w/ FF
MP 21.5 RPM 2500 IAS 140 kts 9.2 MPG
then i just moved prop back 100 and let MP do it's thing
MP 22.0 RPM 2400 IAS 140 kts 9.4 MPG
MP 22.5 2300 142 kts 9.7 MPG
MP 23.0 2200 145 kts 9.9 mpg
MP 23.5 2100 138 kts 10.0 mpg
approximations, numbers were fluctuating, and I should have pulled up fuel flow for comparison too....numbers when compared w/ book show approximately same percent horsepower, and i bet FF was similar, but i wonder?
Next time i'll re run and note FF.
steve

[N3322G]

In aviation consumer about 2 years ago there was a chart on aircraft and car miles per gallon. It was hard to tell under what conditions the data was created so I watched the Shadin FF on the next flight in the MPG setting. I like to fly fast and at 24/24 the Twin consumes gas like a Lincoln Navigator ... but it looks much better.

Fun to watch as the winds changed.

[N8632Y]

i hope to get up this week and rerun the test, by:
climb to altitude, where MP can no longer climb, maybe 7500, and run the test, WOT, 2100-2500 RPM, and record speed, MPG, Fuel Flow, and temps on 1 cylinder. This will test at a normal cruise, like a trip profile, which is my best setting.
steve

[Tony Scarpelli]

This is a really good thread. I have a 250 and found that 26/2300 is the best highspeed cruise setting and keeping 2"-3" difference between MP and RPM dropping them down to 23/2100rpm is an excellent low power cruise setting.

[N8632Y]

[Tony Scarpelli]

[MV Case Jr]

[N8632Y]