180 hp best range power setting

Lucky · Post by **Lucky** » Sat Feb 09, 2008 5:44 pm

Howdy all,
I'm the new owner of a '54 170B with a Bush conversion for the Lycoming 0-360 and a cs prop. I'm trying to determine a close approximation for the maximum range power setting. I realize this depends on a variety of factors, but I'm curious what other people are running at when they are trying for an efficient cruise.

thanks,
lucky

blueldr · Post by **blueldr** » Sat Feb 09, 2008 6:21 pm

I think you will find that "MAXIMUM" range is going to be pretty slow. Usually a small sacrifice of maximum range will produce a much more comfortable and faster "LONG RANGE" cruise.
A friend of mine has a Continental IO-360 conversion and has found that on a cruise of at least two hours duration he gets 150 MPH TAS at 7.5 GPH which comes out to pretty close to twenty miles per gallon. Thats about a gain of five miles per gallon over a stock engined C-170.

buchanan · Post by **buchanan** » Sun Feb 10, 2008 2:00 am

Sorry but I don't believe it!!!

150 at 7.5 gph NO WAY!!!

I have a O-360 Lyc. The airplane is clean and light and the best I can do
is 115 kts at 8 gph. I know the Continental isn't THAT much more effficient than the Lyc.

Buck..........Galena, AK

mit · Post by **mit** » Sun Feb 10, 2008 3:41 am

Its all in the airspeed indicator!

Lucky · Post by **Lucky** » Sun Feb 10, 2008 8:21 am

OK, so does anyone know of a substitute owners manual you can use to determine power settings for this engine/prop/airframe combination? I was thinking that maybe a Maule M-7 180 would be close...

c170b53 · Post by **c170b53** » Sun Feb 10, 2008 4:20 pm

Does your conversion have an RPM limitation? That would be the catch. Obviously lower RPMs would give you the best econo cruise. I have a 160hp c/s combo and 22.5 @2300 at 2k Alt. gives the best about 8 GPH at 105 Knots. After that increasing manifold and rpm by a factor of 1 will increase GPH by 1 and speed by about 5 knots for the first increase and the last about 2.5 knots. In other words at 25" 2500 rpm = 10 gal/hr and 112 knots.
Thats the best I can do unless I'm descending. These figures are just estimates and as far as I can tell I have a hull speed thats hard to alter. Again what you gain in most conversions is climb performance, mine is 1000 to 1200 ft/min at sea level.

Post by **GAHorn** » Mon Feb 11, 2008 3:11 am

Drag increases as the square of velocity.... so if you look at the best range altitude/speeds recommended for the standard airplane, it's likely to be very close for any other engine installation on the same airframe. Therefore, whatever MP the engine mfr allows for the lower rpms the prop mfr recomends...which result in the airframe mfr's best range altitude/speed profile will most likely be what you are looking for. (Notice the actual horsepower output the standard airplane delivers in the best range chart and you'll have a horsepower-starting point for your installation's power settings. If you try to go faster than that you'll be burning more fuel than necessary for best range.)

Jr.CubBuilder · Post by **Jr.CubBuilder** » Mon Feb 11, 2008 7:19 pm

Lucky I'm guessing you already know, but in case you didn't, the O360A1A is only rated 180hp for 7 minutes. It should all be spelled out in the engine manual. The maximum continuous output is 145hp (ironic the same as the O300) and you shouldn't really have to worry about it to unless you are maintaining low level and full power. In five minutes you will be probably as high as you want to cruise, and with the drop in manifold pressure at altitude it's hard to find a setting that could hurt the motor.

I have a flight manual supplement, that's rudimentary and came with my STC, pm me if you want I can email a copy if you want.

If you use a manual from another plane to give you numbers, I suspect that one from another later model Cessna might be better than the Maule. I think they made a 180HP 172 RG with a CS prop for a couple of years.

Roesbery · Post by **Roesbery** » Tue Feb 12, 2008 2:25 am

Check your messages

hilltop170 · Post by **hilltop170** » Tue Feb 12, 2008 5:03 am

gahorn wrote:Drag increases as the square of velocity........... If you try to go faster than that you'll be burning more fuel than necessary for best range.)

I just had some first-hand experience with that last week flying a Turbine Birddog with a 317hp Allison 250-B15 engine from Oregon to Alaska. It would cruise about 105k indicated at 85% and 18gph. Push it up to 100% and fuel flow went to 28-30gph and speed went to 115k indicated.

Robert Eilers · Post by **Robert Eilers** » Tue Feb 12, 2008 2:13 pm

Hmmmm - turbine powered Birddog - isn't that a little like installing a V-8 Hemi on a buckboard?

blueldr · Post by **blueldr** » Tue Feb 12, 2008 5:39 pm

By golly, thats's pretty impressive!

Almost seven miles per gallon!

Leave it to the Italians to develop a better Bird Dog.

Post by **GAHorn** » Tue Feb 12, 2008 6:46 pm

Some U.N. ambassadors were visiting and the question came up what heaven would be like if there were a heavenly U.N. The discussion came to the supposition that:

In Heaven:

The Swiss would be the Administrators.

The Italians would be the Lovers.

The French would be the Chefs.

The Germans would be the Auto Mechanics.

And the British would be the Police.

This led to the discussion of what Hell would be like. It was imagined that:

In Hell:

The French would be the Administrators.

The Swiss would be the Lovers.

The British would be the Chefs.

The Italians would be the Auto Mechanics.

And the Germans would be the Police.

c170b53 · Post by **c170b53** » Tue Feb 12, 2008 10:13 pm

On our field is a PT6 powered Seebee. It utilizes a 3 bladed prop, looks mean with its streamlined nose and in cruise it burns 36 gal/hr. I guess if you have the money for the conversion, your truely have money to burn.

hilltop170 · Post by **hilltop170** » Wed Feb 13, 2008 1:10 am

blueldr wrote:By golly, thats's pretty impressive!

Almost seven miles per gallon!

Leave it to the Italians to develop a better Bird Dog.

blueldr-
Not only that, but Jet A averaged $5.32/gal mostly due to the Canadian fuel stops. The 16.7 hour trip cost $1653 just for fuel!

I'm glad I wasn't paying the bill.

It was a real good demonstration of hull speed if that term applies to airplanes as well as boats. Reminded me of a tug boat, it doesn't matter how much horsepower you put in one, it's not going any faster.

I am told if you can get up close to the flight levels, TAS picks up quite a bit (if you can hold your breath that long) but that kind of defeats the purpose of the design.

Once again, I think Cessna probably got it right the first time.

It does climb though, over 2000fpm at 100% at gross 2800#.