I went with the TSIO permold case 7th stud case. Front mount alternator.. My weight includes heavy stuff...like the full size alternator, starter and series 1200 mags. Have the light weigh alternator and starter now....not installed yet....may go with electronic ignition later. Should shed nearly 20 pounds. May have LEES build a custom exhaust system. Using a bonanza exhaust system now...doesn't fit my cowl quite right.

How does a 470 respond to being run at low power settings consistently?

whee wrote:How does a 470 respond to being run at low power settings consistently?

TCM recommends minimum 2300 for cruise on some models.

They had some balance weight problems with some engines at lower cruise rpm's.

I usually run the O470K in my C180 at around 21" / 2300, good for 138-140 IAS & about 11 gph. This is based on fill-ups, not on a fuel flow meter or totalizer. Quite often, I find myself pulling it back to 17 or 18 inches with that same 2300 when I'm surveiling and not going anywhere to speak of. Do that much on a flight & the burn seems to be down to about 10 gph. This is based on tach time BTW, not wristwatch time. I log all my flying hours using tach time, easier for me to keep track that way.

TangoFox wrote:TCM recommends minimum 2300 for cruise on some models.

They had some balance weight problems with some engines at lower cruise rpm's.

I found CSB09-11A which is what you are referring to I think. Only 470s affected are the O470g and the IO470N. Thanks TF.

Thanks for the data point Hotrod. I'm looking to run regularly under 10gph and that's a pretty low power setting for the 470.

My take is that an engine burns X amount of gas per horsepower produced. Whether you run a 200hp engine @ 70%, a 230hp at 60%, or a 260hp at 55%, they're all gonna burn about the same amount of fuel because they're all producing about the same amount of power. An injected engine might burn a bit less than a carbureted engine due to better efficiency, but maybe not. Fuel burned is power produced, whether it's spread evenly between the cylinders or not.

whee wrote: I'm looking to run regularly under 10gph and that's a pretty low power setting for the 470.

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In the 205 I average 10GPH on a typical trip. 1.1 en route at gross weight.

Sea level to 10,500 and back again.
Climb @ top of the green on MP & RPM and hold top of the green on MP adding throttle until throttle is full in. 100 Degrees ROP for climb.
When I reach 10.5 I level off for about 15 minutes At 2300 rpm & 50 ROP for cruise. Then gradual descent back to sea level backing off the throttle to maintain 18-19" MP.

Cruising at low altitudes (2k or less) I get about 11 GPH typically 23 squared.