Can we talk about fuel burn for a moment?

I used to own a later model 182 with a TIO-470 (STC'ed) and it really made me really sensitive to fuel burn as an operating expense. It would sucks down 14-15 gph, and that was just too expensive for it to be fun anymore (fuel prices were $6-7/gallon at the time as well).

I'm considering buying a maule and very hesitant to go to an even bigger bore engine (O-540) but maybe the de-rated part and lack of a turbo and all that makes a big difference. I'm kinda thinking the -210 models might be a perfect fit and happy medium, but can you -235 and -210 model fliers post the fuel burns you would expect for flight planning purposes based on how you actually fly? Would appreciate it!!

One other related question - are there any "gotchas" with the IO-360 at 210hp? I'm thinking the increase in HP over normal for that engine is probably a result of higher compression ratios and I wonder if that means a shorter TBO. I'd consider the 220hp franklins as well but after owning an unsupported STC'ed engine, I shy away from anything too unusual or unsupported.

(Gee... guess I learned a lot from that 182... that thing was a nightmare!)

I fly with a friend who has a PPonk'ed 470 C-182 and he burns at least one or two gph more than my O-540J1A5D at same speed and altitude.

I think an IO-540 will do even better than my engine. At cruise at 9.5k or 10.5k I am at about 11.5 gph and probably could push it down even farther.

Obviously pouring fuel down four holes vs six will yield a lower fuel burn. It all depends on if your missions are going to need the extra horsepower.

The TBO of the 540 is 2,000 hrs which I think most -J1A5D's make, but I have no idea what other engines project or make.

IO540W1A5 (injected 235) and at 75% I'm burning 12.5 +- A little. Could throttle back but the old girl (M-6) is lazy enough at that.

M-6-235 with IO-540W1A5D

At low altitudes (below 5000') at 22" and 2200 rpm I burn 11.2 gph. That is leaned to peak EGT. On 8.50s, that yields a speed of 140 mph in smooth air. Much slower on Bushwheels.

M-6-235 with IO-540W1A5D

At low altitudes (below 5000') at 22" and 2200 rpm I burn 11.2 gph. That is leaned to peak EGT. On 8.50s, that yields a speed of 140 mph in smooth air. Much slower on Bushwheels.

M5 180 gets 8.5gph at 130 mph 24 squared. If you slow the 540 powered Maules to 130 mph you could get real close to that and still have some power reserve when you need it. We chose the 180 hp because I didn't want to feed the 540 and am happy with the choice as it does what I need it to do. In a 750 mile trip I'll burn 44 gals in 5.75 hrs which yields 17 mpg across the ground. Not bad for a vehicle that goes 130 mph. If you flew a 540 powered Maule at 145 and 12 gph you would arrive at the destination 6 tenths of an hour sooner and burn 62 gals or avg 12 mpg. Still not bad mileage with a half ton useful load. Your mileage may vary

You asked about the 210 and 235 engines. Mine's a 180 hp O-360-C1F. With the 31" tundra tires and unfaired ABI SD gear legs, I get about 9.5 gph fuel burn and a no-wind ground speed of around 109mph (95 kts). With all that drag, increasing power gives only a modest speed increase but a lot more fuel consumption.

When I was in the Idaho back country last August, at about 2350 lbs and density altitude around 7,000, I got about 300 fpm climb with no wind. That's when the 6-cylinder fuel injected engines perform much better. The 6-cylinder engines also give you a faster cruise speed than the 4-cylinder engines although with a fuel burn penalty of about 2 - 3 gph more. Things that I like better about the 4-cylinder engines: less nose weight means less chance of nosing over if you apply the brakes heavily to land shorter; more useful load; lower maintenance cost.

I have a 1977 M5-210. The 6 cylinder continental is a love it or hate it type of engine. This is my second M5-210 and have loved both. I just put in a factory reman'd last fall and have 75 hours on it. I run it 2400 RPM and 23 inches, leaned out to 10 gallons per hour at 3,000 feet and see 135 mph with 4 tanks full of fuel and loaded to the gills inside.

Fuel used per hour is pretty directly related to horsepower setting the pilot selects.
Injected engines are a bit more efficient than carburetted engines.
.43 to .48 lbs per hp per hour is a good calculation.
180hp at 63% is 113hp 235hp at 63% is 148hp
At 63% hp on the 235 one can operate ROP or LOP with no fear of damaging the engine, however more than 63% one must lean more carefully.
Prop thrust efficiency of course comes into play if the prop is not a good match for the engine.
Best distance covered for least fuel burned is 55% hp, and best loiter power (most time in air but not best distance covered) is 45% hp I am told.

Bit of thread drift but apropo

THIS IS A VERY USEFUL AND INTERESTING THREAD!!!

M7260B, 29" tires, at gross or a little more (camping gear, 80 gallons of fuel)
Cruising at 10-12,000' from SLC to southern Utah at 115IAS
2150rpm (none of the needle gauges vibrate at that rpm )
WOT/LOP, iridium plugs-they do make a difference in LOP operation IMHO
9.8-10.2gph
I can obviously go faster, but I like to look around so why hurry.

IO-540W1A5D on my M-6-235, with 29" AK Bushwheels, long wings, and extended gear to all help slow me down - I'm typically sightseeing down low at 22" MP / 2200 rpm, leaned to slightly lean of peak, and expect about 100 kts true at 10.7 gph. Or pretty close to 9 mpg, according to my EDM900.

Interesting about the Iridium plugs- curious how much of a difference they make. Been thinking about maybe switching to the Iridium plugs on the low side only.

AJ