hotrod180 wrote:I think there's a TCM SB cautioning against running at low MP.
I checked it & it doesnt apply to my 470K.

if it's the one I'm thinking of the SB cautioned against running high MP with low RPM because the counterweights can be "de-tuned". I think "low RPM" meant 1500-1800 or less and high MP meant just that... close to WOT.

billjesstaylor wrote:

Mountain Doctor wrote:Two Points:

One, In a Maule with high performance airframe characteristics it needs a high performance motor. As an owner of a perfectly capable 180 HP, I recommend the 235 or the 260 if at all possible. In the backcountry, power improves safety and utility. A lot.

Two, I run my 180 at 55-65% quite a bit also. Many flights I'm just savoring the time aloft and in no rush for the pleasure of flight to end. If I lean aggressively the plugs won't foul.

Thanks for sharing your experience with your 180 Mountain DR. I spoke to Aero101 over at the Maule site about his MX-180 fixed pitch. I think it is the “180 A” model Maule. It seems he was very happy with his ship and the 80x44 prop. I haven’t looked into what prop that model normally comes with.

I like the capability of the 235. I just don’t want to, actually I can’t afford to feed it 12-14 gph all the time. So that’s what raises my concerns about loafing around at the lower power setting as habit.

I haven’t checked into average overhaul cost between the lyc 180 f/p, 180 c/s, and 235 hp engines either. When I do, that may also sway me to one way or the other.

Currently I’m in a flying club with a piper warrior. The annual just finished up. The mechanic said he found ALOT of fouling at the lower plugs. He used a dental pick to break the lead free. The chunks were rather large. I routinely fly at about 55- 65% power and lean aggressively. But I don’t know how the other 9 members in the club fly it. Its a Lyc 320.

O-360's foul easily if not leaned at low power settings. After start lean till just barely runs, and giving throttle will make it quit. This is also safe practice to avoid starting a takeoff roll without mixture adjusted properly.

At low power settings lean until she's rough and richen a hair from there. I like to run at peak EGT in this situation. I recommend this only with a 4 channel engine monitor and the knowledge to interperet it accordingly. This is a key. You (essentially) can't overlean at less than 75% but you have to know what you are doing and how to monitor the engine. Catch up reading John Deacon.

As far as price of gas goes, I suggest it's irrelevent. Given the cost of this sick activity it's a small component. Indeed, I'd question if a person has the money to enjoy airplane ownership if a couple GPH one way or the other matters.

If you wish, get an O-540 with Mogas ability. Best of both worlds.

As far as overhaul goes, I'd estimate the 6 cylinder about 50% more than the four cylinder.

As far as the 180-A's go, it is what it is. Fine planes but limited in ways that don't affect the larger testicled Maules.

Mountain Doctor wrote: As far as the 180-A's go, it is what it is. Fine planes but limited in ways that don't affect the larger testicled Maules.

For that reason alone, I often consider if it’s worth upgrading mine to at least a “-B”. Next step from there turns me into an M-6-235B.

Mountain Doctor wrote:
As far as price of gas goes, I suggest it's irrelevent. Given the cost of this sick activity it's a small component. Indeed, I'd question if a person has the money to enjoy airplane ownership if a couple GPH one way or the other matters.

I think that is valid point/perspective. I'm probably being overly critical about the gph.

Think I'll just have to catch a ride in various ships to see what trips my trigger and then get in touch with Jeremy and/or Wup for consultation once I get a little a little closer to pulling the trigger on something.

mtv wrote: At one point while I was running Huskys pretty regularly, the question of running engines "over-square" came up. Over-square meaning running the rpm at a relatively low number, compared to the manifold pressure. So, for example, 1900 rpm and 21 inches is considered "over-square". ...

I've had my C180 about 3-1/2 years now.
When I first got it, I'd read that the "best" moderate power setting was 21" / 2300 rpm, so that's what I used.
After a year or two, I started using 22 squared, mainly because it was easier to remember.
More recently, I started using 22" / 2100 or if wanting a bit more speed 23" / 2200.
If nothing else, running over square runs up the tach time a bit slower.
FWIW 21 / 2300, 22 / 2200, or 23 / 2100 all show about the same fuel burn, % of power, and IAS on my power charts.

My maule M7 235c has 3600 hours on it. Engine replaced by the prior owner at 2000 (TBO) because he was obligated to by insurance for one of his regular missions. It was still great at that point. The engine I'm running is also doing great.

He ran and I run at 55% as a matter of normal operation.

There are tons of 180HP Maules out there for great prices. There is a reason for this. 235 is the sweet spot, enough juice to get you out of most anyplace you would want, but still a bit lighter than the 260.

Just a thought, % power seems to be being discussed as an RPM dependent function:

Pilots not flying behind an altitude engine commonly mistake % power with RPM settings. For example, flying behind a carbureted O-320, you're at 75% power at redline (2800 RPM) at 3,500' MSL. % power in normally aspirated engines is usually expressed in brake horsepower that's dependent upon RPM and density altitude. Turbine operators sometimes forget to make the mental transition.

I guess the important point is that if you're pulling the throttle back to 75% of redline and you're not behind a turbo- or supercharged piston engine you're running WAY under 75% power at cruising altitude. This is begging for carb ice depending on the make/model of aircraft you're flying. I'd hesitate to fly a carbureted engine under the green arc, that's pretty much why it's there.

One thing I found when running low power setting is it may take some time to get used to the new sounds and new vibrations. I run 2000 rpm and 23” pretty regularly in my avcon converted c170 with a constant speed prop. The sounds and different vibrations it makes are not alarming by any means, just different.
If you get the chance get the big engine, and slow it down.

hotrod180 wrote:

mtv wrote: At one point while I was running Huskys pretty regularly, the question of running engines "over-square" came up. Over-square meaning running the rpm at a relatively low number, compared to the manifold pressure. So, for example, 1900 rpm and 21 inches is considered "over-square". ...

I've had my C180 about 3-1/2 years now.
When I first got it, I'd read that the "best" moderate power setting was 21" / 2300 rpm, so that's what I used.
After a year or two, I started using 22 squared, mainly because it was easier to remember.
More recently, I started using 22" / 2100 or if wanting a bit more speed 23" / 2200.
If nothing else, running over square runs up the tach time a bit slower.
FWIW 21 / 2300, 22 / 2200, or 23 / 2100 all show about the same fuel burn, % of power, and IAS on my power charts.

Over square will run higher CHT’s though. For us (C180, O520) 10 -15 deg cooler running 23/2400 as opposed to 24/2300. Typically 23 square is the sweet spot for us.

Yes, folks, PULEEESE read your aircraft POH, AND your engine manufacturer's operators manual, and follow their guidance, regardless of what you read on the internet.

Lycomings and Continentals are very different animals, as are different models within each line. Don't assume that what's okay for one model is necessarily applicable across all models of that manufacturer, let alone trying to apply one manufacter's procedures with the others.

And, if you have any questions, for example, what you've read on the internet, I highly recommend you call the manufacturer's tech reps and talk to them about it. In my experience, both Lycoming and Continental have very knowledgeable Tech Reps.

MTV

mtv wrote:Yes, folks, PULEEESE read your aircraft POH, AND your engine manufacturer's operators manual, and follow their guidance, regardless of what you read on the internet.

With that thought in mind, my Maule POH has zero information on power settings in it. I went to Lycoming support web site and downloaded the performance information for my engine from them.

On the question of how much in dollars one saves by slowing down or going to a smaller engine, I just did a quick calc on the two airplanes I have the most experience in, my own 180hp Lycoming, CS P172D (Avcon conversion) and just about any stock older model 182 with the 230hp Continental O-470. When I flew 182s regularly, leaned at a "normal" altitude of 10-11,000' MSL, I could expect 135 knots at 13.5 gph. With my airplane, I routinely anticipate 115 knots at 9.8 gph at that same altitude. So with those figures in mind, the difference in cost to fly 1000 miles (no wind, of course) is $65 less for the smaller engine at gas prices of about $4.30/gal 100LL.

To the basic question that's being discussed, though, it really depends on how much less than 75% power. I think if you routinely ran really slow, you would cause some problems, but how slow is "really slow"? A NA engine operated in the high country never gets to 75% power, except maybe on a really cold day. When your routine altitudes are in the 10-11,000' range, you're only talking about 55% power at best, depending on DA. But engines will run at much lower percentages, and it can be problematic if it's too low---but I don't know where the dividing line is. It's kind of like the definition of pornography--I know it when I see it, but a lot of skin can show before the line is crossed.

When I was partnered in the TR182, we had it on the line to be rented by persons either working on their commercial or who already had their commercial, largely because the FAA had recently changed the commercial requirements to include complex airplanes, and it was about the least expensive complex airplane on the field at the time. One of our renters, Andy, was bragging one day about how he'd been flying the TR182 at only about 110 knots, just keeping both the rpm and the MP barely in the green, and burning a whole lot less gas--don't remember how much. We'd started having problems with fouled plugs, a situation we'd never had before, because everyone else was running it at 23-2400 rpm and 24" MP, because that's what I'd taught each of them on their checkouts, based on the POH. But Andy had been checked out in the airplane while I was on vacation, and that CFI hadn't followed the book. My pard and I conferred and decided that we had to either stop renting to Andy, or he'd have to fly it like everyone else. My pard talked to him, and the upshot was that we stopped renting to Andy. Nice guy, but knot-headed.

My own view has been that I want to go as fast as the airplane will allow, with reasonable attention to running the engine frugally and gently, i.e., not balls to the wall all the time, and properly leaned. Most airplanes have a "sweet spot", typically a range in which the airplane seems to get good mileage and has good speed. With my little bird, I've become accustomed to running it at 21" and 2400 rpm, but I admit that that is more my "feel" for it than anything religious. More power gains very little more speed with its draggy airframe. Less power, and the airspeed drops off quickly. Of course, as soon as I climb above about 7000', I can't maintain 21", but I still run 2400 rpm. I steadily burn 9.8 gph in cruise, more in climbs, less in descents, but it still averages about 9.8 gph, according to my EI fuel computer.

All that FWIW.

Cary

There is a lot of dated information out there on engine operation. Much of this old lore comes from radial engine operation and really does not apply to flat 4/6 cylinder engines. I actually learned to fly in T-28's with radials, that stuff applied there, not necessarily to your piper cub. No two engines unless they are the same design and mod number operate the same. It really is not possible to make broad generalizations between families of engine. If you know somebody that operates the same model as you do in the same installation, then there is a valid comparison. Small variation in accessories, fuel delivery and cooling flow can make differences in performance and power coupled with wear on components. Really your best resource is the manufacturer, they actually tested your engine in your configuration. The green arc is there for a reason, so is the yellow and the red line.

There are so many factors on what is a safe operating, or economical short term or long term (including overhaul) operating cost. I have literally paid for my sons higher education on the cylinders we replaced at my repair station from various creative operating cost saving measures. I have literally heard them all and accept the check for the cylinders regardless. Even when you do everything right you can have issues, engines are a bit their own creatures and have a personality. So I would stick to your manufacturer's recommendation. I did some research at Soloy doing twin pack research, we ran the engines for 3,600 hours in various power settings to gather data and wear data. Lets see, that is 50 gallons per hour per engine (2) x 3,600, thats 360,000 gallons of fuel. We didn't do that for fun. So if you want to do your own testing, go for it, it may work out for you. Personally I have had 5 complete engine failures in my career, one a dual flameout. I am over it. I run rich of peak and cruise in the middle of the range. Flying is expensive, if you want to save money, drive a hybrid, don't fly. I have run out of cats personally.

billjesstaylor wrote:

Mountain Doctor wrote:
As far as price of gas goes, I suggest it's irrelevent. Given the cost of this sick activity it's a small component. Indeed, I'd question if a person has the money to enjoy airplane ownership if a couple GPH one way or the other matters.

I think that is valid point/perspective. I'm probably being overly critical about the gph.

Think I'll just have to catch a ride in various ships to see what trips my trigger and then get in touch with Jeremy and/or Wup for consultation once I get a little a little closer to pulling the trigger on something.

Agreed with above. My mx bill was more than my gas bill in my first year. Not to mention all the others costs I don't feel like thinking about. Not sure the extra 500-$1000 per year savings between a 235 and 180hp engine really makes a dent. That said I just started running MOGAS most of the time. I figure the money I save will just about buy a new engine when it comes time. Not sure any Maules can run it. Might be a potential cost saver to find something with an o-470 (and STC'd)

I have owned over 50 Maules...The only way to do harm to a Maule is crash it...You can run ANY of their engines ANY way you want to...Rockhopper kind of said it like it is.. The 180's with a constant speed prop handle a little nicer than the 235's, only as it's a little better balanced, not as nose heavy...But you can get a 235 fuel burn down to the 8's if you just back off the throttle..If you are gonna travel heavy often, the 235 would probably be better...The (legal) useful load on the 180's are higher...I have heard of guys flying the 235's over gross ...But I wouldn't know much about that...
If you get a 180, get a constant speed..But throw away the 76" Hartzell and get a long 2 blade, like a MT or ?? Huge difference..

They were tired engines in beat up Pawnees and CallAirs, but we used whatever kind of regular gas we could in various models of the O-540 Lycoming throughout the 20th century. We got it at the local gas station. Had to keep the electronic fuel pump on in the CallAir.

Flymac wrote:I have owned over 50 Maules...The only way to do harm to a Maule is crash it...You can run ANY of their engines ANY way you want to...Rockhopper kind of said it like it is.. The 180's with a constant speed prop handle a little nicer than the 235's, only as it's a little better balanced, not as nose heavy...But you can get a 235 fuel burn down to the 8's if you just back off the throttle..If you are gonna travel heavy often, the 235 would probably be better...The (legal) useful load on the 180's are higher...I have heard of guys flying the 235's over gross ...But I wouldn't know much about that...
If you get a 180, get a constant speed..But throw away the 76" Hartzell and get a long 2 blade, like a MT or ?? Huge difference..

Holy @#$!...50 Maules?

-Aero101 ran a fixed pitch 1a200DFA 80X44 on his Maule 180A. Made by McCaully I think? If I got into a 180B I’d try to put that prop on...Unless there is something better performing?? I like the specs of the 180B for the fuel capacity and 48 degree flaps.

-I understand it probably won’t break ground as early as a Super Cub, but once aloft and at GW, any issues with keeping up with the 150/160 hp Super Cubs (also at GW) in Alaska? Right now I live in central WI but plan on retiring in Alaska. Never flown in Alaska so I don’t know enough to even know what I dont know. I’m not sure what altitude guys are going through the mountain passes, etc. I absolutly plan on getting additional/specialized training once I get my own plane and prior to going off on my own in that part of the country.

Considered starting a different thread regarding my Maule 180B specific questions and how it relates to other backcountry aircraft...Specifically a 150 or 160 Super Cub, but don’t neccessarily want to start a Maule vs Super Cub pissing contest. That’s probably somewhere on the forum anyway. So I think I’ll stick to keeping my questions in this thread.

Another thing to note is I’d upgrade to the extended gear and 31” tires for better backcountry performance whether i went with a 180 or 235 hp Maule.

100 low lead! That is the problem facing the 80% of the ga industry that doesn't require high octane fuel. Maybe more than 80%. I don't know,just what I've read.
Reality is a small low compression engine requires high power settings just to initiate the reaction that removes lead from internal engine parts. There is a chemical in the fuel to aid in this process but it takes a decent amount of heat to work. They shouldn't even make the stuff or for that matter force us to use it by making it our only airport option.
Think about it for a minute,2018 and we are still using ww2 fuel.

Railchummer wrote:Just a thought, % power seems to be being discussed as an RPM dependent function:

Pilots not flying behind an altitude engine commonly mistake % power with RPM settings. For example, flying behind a carbureted O-320, you're at 75% power at redline (2800 RPM) at 3,500' MSL. % power in normally aspirated engines is usually expressed in brake horsepower that's dependent upon RPM and density altitude. Turbine operators sometimes forget to make the mental transition.

I guess the important point is that if you're pulling the throttle back to 75% of redline and you're not behind a turbo- or supercharged piston engine you're running WAY under 75% power at cruising altitude. This is begging for carb ice depending on the make/model of aircraft you're flying. I'd hesitate to fly a carbureted engine under the green arc, that's pretty much why it's there.

Strange observation... I have NEVER heard another pilot equate operating at 75% of redline RPM to "running at 75% power"... Most of us trained in C172s (or similar O-320 powered airplanes) would know that at 2025 RPM (75% of the 2700 RPM redline) you would be nowhere NEAR 75% power. Heck, the Cruise Performance charts for those airplanes don't show any power settings below 2200 RPM, as a general rule...