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150 HP vs 180 HP

Charlie Longley

Charlie Longley

MEMBER
Anchorage, AK
I know the old saying is "There is no replacement for displacement!" But I am helping a friend look for a Super Cub to put on floats. And the 150 HP Cubs tend to be $10-15,000 cheaper then 180 HP cubs. I have no questions about having a 150 HP for a landplane. But how much of a difference does the extra 30 ponies make on a Seaplane? The intended use is for floatplane time building with an eye towards switching careers from a Commuter job to an Alaskan Bush job. Probably EDO 2000's for the floats.

Any experienced answers would be appreciated!
 
180 hp will give you a shorter takeoff and better rate of climb. How much, that's at bit hard to say. Takeoff is probably 15% shorter, rate of climb maybe 30% better. But if you are building time, the 150 hp will be fine, just make sure you have a borer prop.

Mike
 
if he is time building get a j-3 with a c90, i have a cub with a 320 and one with a 360 the performance diff is noticeable on floats but cruise is only 2-3 mph better with the 360. the fuel burn with the 360 is also noticeable at 8.5+gph as apposed to 5.7 with the 320. you will also learn alot more with a lower hp plane
 
the fuel burn with the 360 is also noticeable at 8.5+gph as apposed to 5.7 with the 320
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Any 320 cub with a 82" prop running a typical power setting burns 8+. No way 5.7. I get 8.2 -8.7 gph so a 180 has to be north of that.... I know if i was looking for a 180 bigger fuel tanks would be mandatory not just a desire.
 
cub12 said:
if he is time building get a j-3 with a c90, i have a cub with a 320 and one with a 360 the performance diff is noticeable on floats but cruise is only 2-3 mph better with the 360. the fuel burn with the 360 is also noticeable at 8.5+gph as apposed to 5.7 with the 320. you will also learn alot more with a lower hp plane
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Hard to tell the 'mission' .. but agree with Cub12 a good time builder is a J-3 or PA-11, if he is like most flying will be light/solo anyway. Hard to beat the operating costs of a C-85/90 Cub.
 
Little_Cub said:
Hard to tell the 'mission' .. but agree with Cub12 a good time builder is a J-3 or PA-11, if he is like most flying will be light/solo anyway. Hard to beat the operating costs of a C-85/90 Cub.
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I have the 150 in my cub and a fuel flow meter. I lean it out looking at the flow rate and I get 6 to 6.5 gallons per hour at about 2200 RPM. Ground speed with no wind about 85 with bush wheels and borer prop

Bill
 
I have flown my cub with 150 hp and 180 hp. They both burn the same amount of fuel at the same cruise speeds, all based on my fuel flow monitor. In other words, same hp output / same fuel burn. But the 180 CAN burn more fuel if you ask it to make more hp. Basically, all of these engines burn very similar fuel / hp. I lean on egt, and aim for peak egt when cruising.

Back to the original question: Just about anything will do for building time on floats, but a 150 hp cub with a borer prop will give you lots of options and will only limit you on the smallest or highest takeoff locations.

For my mission the 150 cub did just about everything. The 180 hp cub does do everything I need for my mission which is alpine lakes, some are kinda small and high.

Mike
 
I thought about a O -360 before I bought my cub ( a 160 O-320). The ability to get the auto gas STC (at that time) was the deciding factor. I currently pay almost $2.00 per gallon less for 91 octane non ethanol mogas vs 100 LL. Thats a lot more flying per $$. If you want to reduce your costs, it's hard to beat the mogas option. If you aren't operating at high altitude, the 150 or 160 should be plenty.
 
Alaska_Rallyer said:
Any 320 cub with a 82" prop running a typical power setting burns 8+. No way 5.7.
Click to expand...
Sorry, I burn 5+ Canuck gals/hr, that's about 6 US gph. That's by hrs & 5-gal gas cans, and lately with my JPI thingie. (Souped up 0320)

Ursa Major said:
I currently pay almost $2.00 per gallon less for 91 octane non ethanol mogas vs 100 LL.
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That's another good reason! (Some burn 91 in their 0360's)

Bill Ingerson said:
I have the 150 in my cub and a fuel flow meter. I lean it out looking at the flow rate and I get 6 to 6.5 gallons per hour at about 2200 RPM. Ground speed with no wind about 85 with bush wheels and borer prop Bill
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What Bill said. :)
 
A stock 150 PA-18 on EDO 2000 floats is a great performer without any modifications. In fact, for someone who is learning, 150 hp is too much. It does not stay on the water long enough for the student to learn the water handling techniques which are important to know when flying heavy airplanes. It is good practice to use partial throttle when learning. A standard land plane prop will work just fine.
 
Theoretically one should be able to match fuel burns with different engines and the same airframe at the same speed and weight, etc.

Practically it doesn't seem to work for me. The O-320 -150 seems to suck 9 gph, and the 160 conversion seems to be around 7.5. The 160 pulls better. I plan on ten in my AEIO360, but I run it at 24 squared.

Works for cars too - my six cylinder Mustang got 24 mpg, and the V-8 version gets 14. I drive them both the same way.
 
Yep Bob.. the way it works. Pulled over at a RIDE check last night and the cop called me a "co...sucker".. I said what and he said is that your mileage 13.2litre/100km and I said yah and I haven't cleared it since pulling my 34' float trailer. He burns 18.4 litre/100km with his ECOBUST 6 cylinder in his F150.. I have the 5.0 V8 Coyote engine from the mustang.

Also show how far they stick their heads in the vehicle if he could read my dash.

Buddy with an O-360 in his Rebel on floats.. is burning less fuel than I do with my 150hp O-320 on floats.


Oh.. and if someone really wants to learn how to fly floats... I have a J3C65 on 1140s!
 
the 0320 i run has been hot roded and burns less fuel then other stock 320 the 5.7 gph i gave in a previous post is leaned out in cruise. i figure it burns less fuel because it is not working hard with a fixed pitch prop, in climb full rich i see about 13.5-14 at 70mph 2600 rpm. don't know how that stacks up to a stock 150hp
 
The 180hp will burn way more fuel (than the 150) if you are working it. The 180hp climbs much better than the 150 and gets off the ground/water much better. You pay a price for that performance. The 180 is not as smooth, weighs more and you will need to carry power to land short. Your cub will be nose heavy with the 180, ecspecially so if you run the Pawnee prop. I prefer the 160....
 
cub12 said:
the 0320 i run has been hot roded and burns less fuel then other stock 320 the 5.7 gph i gave in a previous post is leaned out in cruise. i figure it burns less fuel because it is not working hard with a fixed pitch prop, in climb full rich i see about 13.5-14 at 70mph 2600 rpm. don't know how that stacks up to a stock 150hp
Click to expand...

That's what my hotrodded 0-320 burns in cruise 5.5 to 5.8 depending on how far I push in the fuel knob and leaned way back
 
holy cow buggs! thats great my 200hp 360 sucks back 17.5-18 gph full throttle in a climb! good thing it climbs fast so i can close the tap. in cruise leaned out it's at 8.5gph
 
Either I do not know how to lean, or my math sucks. If I do gallons vs. Hobbs time I come out way ahead. Are you guys using a fuel flow meter to get these numbers? Most use the increased flow on climbout and the decreased flow on descent, averaged in with those cruise numbers. It is difficult to compare apples and oranges.

I believe gallons divided by tach time is probably the most accurate way to do this. It includes all phases of flight, but ticks over more slowly when you are not demanding gobs of power, and in most cases approximates actual flight time.
 
A light 150 is hard to beat light. Heavy on floats as stated is where the 180 shines loaded. I have the c4p 180 and it climbs great gets off good, but wouldn't do it over. I fly mostly light and a 150 hp would be my choice now. I would take the long wings off too if I were to do it over.
 
bob turner said:
Either I do not know how to lean, or my math sucks. If I do gallons vs. Hobbs time I come out way ahead. Are you guys using a fuel flow meter to get these numbers? Most use the increased flow on climbout and the decreased flow on descent, averaged in with those cruise numbers. It is difficult to compare apples and oranges.

I believe gallons divided by tach time is probably the most accurate way to do this. It includes all phases of flight, but ticks over more slowly when you are not demanding gobs of power, and in most cases approximates actual flight time.
Click to expand...

My numbers are from my fuel flow instrument in cruise. Last year a friend in a 108hp supercub and I coming home from New Holstien went 5 hours and 20 minutes before stopping for fuel and both of us had an hour left in the tank, I have 2- 18 gallon tanks and a 2 gallon header tank. Do the math
 
Tim said:
My numbers are from my fuel flow instrument in cruise. Last year a friend in a 108hp supercub and I coming home from New Holstien went 5 hours and 20 minutes before stopping for fuel and both of us had an hour left in the tank, I have 2- 18 gallon tanks and a 2 gallon header tank. Do the math
Click to expand...

The year before he was burning slightly less then I was in my C-90. It was around 5.5 GPH. Granted I was running 2400rpm and I'm sure he wasn't, but it was aggravating every time I would put 16.5 gallons in he would put 16.3 and be filling up.
 
I have a fuel flow meter that I check often for calibration and has always been spot on. I think everyone should put a fuel flow gauge in their aircraft. It will really open your eyes and make you use your mixture control regularly and run at best efficiency. I lean at any altitude. This is contrary to how the majority were trained in the old days to ignore the mixture unless you are at high density altitude or >7K ft.
 
Bugs66 said:
I have a fuel flow meter that I check often for calibration and has always been spot on. I think everyone should put a fuel flow gauge in their aircraft. It will really open your eyes and make you use your mixture control regularly and run at best efficiency. I lean at any altitude. This is contrary to how the majority were trained in the old days to ignore the mixture unless you are at high density altitude or >7K ft.
Click to expand...

I completely agree with Bugs' comments about leaning and a fuel flow transducer. With a multi-probe egt and cht you know what safe leaning is.

When I had a PA18 with 160 hp I figured 6 gph was a good average. Now with an O340 and electronic ignition my burn averages under 5. If open the throttle I'll see a higher burn but I've never seen an average over 8. I too check my average every time I top off with my hour meter (not tach time). I've gone over 8 hours before quite a few times with 44 gallon tanks and had over an hour reserve when I filled it.
 
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Since there is no "Free Lunch" there are no cases of old aircraft engines that burn much less fuel under the same conditions than some others.
All of our old Continentals and Lycomings burn .40 to .45 lbs of fuel per hp-hr. No exceptions There are no old aircraft engines burning less than that and even then the engine must be leaned properly. Screw it up and you can easily burn .50 lbs per hp-hr. Not to mention that on takeoff with the enrichment device of a Marvel Schebler carb dumping even more fuel into the stream, .70 lb or more is common.
That means that with 6 lb/gal then:
.40 lb/hp-hr = 0.067 gal/hp-hr
.45 lb/hp-hr = 0.075 gal/hp-hr
so if you are burning 8.5 gph in a 150 hp 0-320, you are at 8.5/.067 to 8.5/.075 = 127 to 113 hp
127/150 to 113/150 = 85 to 75% power

Burning 6 gph? then:
6/.067 to 6/.075 = 90 to 80 hp
90/150 to 80/150 = 60 to 53% power

These numbers are always in the right ballpark. Burning a small amount of fuel? then you are at a low % of rated hp.
Lycoming 0-320-B Fuel Flow resized.jpg
 

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Darrel, do you know what the dogleg in the graph at ~76% power is about? Is this the auto-rich feature of the carb, or some sort of cooling issue requiring greater fuel flow?
 
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