O-360 vs O-320 in a PA-12

[KJC]

Ive been toying with the idea of installing a 180HP instead of a WD150HP in my PA-12 rebuild. The cost of the initial purchase on the used market seems to be close. Soooo....

Fuel Burn..It has standard 38 gallon fuel
Weight..?
Who has the STC for the 180? Is it available? Someone said maybe Dans?
Will it be nose heavy compared to the Kennmore STC for the 150? Will the WB work on floats?
Has anyone ever flown one with the 180?
Is the speed increase worth the fuel burn?

Thanks

[Speedo]

I believe Charley Center has an STC for the 180. Requires square tailfeathers. The cowling changes, too, as I recall. You'll see Charley in Anchorage at the Airman's show this weekend if you're attending, and you can talk get all your questions answered.

You should not expect a big speed improvement, due to the dragginess of the plane. But takeoff performance will be better.

If you're looking for speed the cheapest way to go (acquisition cost and operating cost) is a constant speed prop. Talk to Brian Sutton (ppibrian) about props for more insight.

[kevin]

I would consider building up the O320 to max horsepower.

[12Geezer2]

I have flown a friends 180-PA-12. It is a real workhorse. He uses it on floats quite a lot hauling moose meat out of the north woods. If you would like, PM me and I'll try to hook you up with him. I would say it depends on what you want to do with the plane. I really like my 150 but I only fly for the fun of it and most of my flying is close to home with most airfields at 1,000MSL or less. When I get out around Johson Creek and that neighborhood I think the 180 would be nice with the higher density altitudes.. If you want to fly mine I might be heading your way in a week or so. I've been told the 180 uses about the same amount of fuel--???--- geezer Dan

[N5126H]

With a O360;
You will see slightly higher fuel burn.
Better climb performance
It will be heavy on the nose
The big prop will act like a drag when power is reduced
increased vibration (perhaps)

With a properly set up and tuned O320 (160hp) (polished ports/and balanced)

You will see slightly less fuel burn
just as good climb performance
lighter on the nose
better looking cowling than Centers STC (for my tastes anyway)
better glide performance
less vibration

Now that being said, I think a well setup and tuned O360, especialyy if it had a constant speed prop and fuel injection would just be better than sliced bread.

[behindpropellers]

I think you are going to find that once you total up all of the extras besides the engine you will have an additional 20K in it. Cowling...Mount..prop.. Just to think of a few.

Tim

[kevin]

Stewart, those are good points. Also, If I was to hang an O360, I would install larger fuel tanks....based off of an average 10 GPH fuel burn

[NimpoCub]

Well, mine's an 18A but maybe similar spec's.
I swing a 41" Borer, previously with a cert. 0320, now with a "Bart 0320" & straight crossover exhaust.
Bart said it puts out "something over 170hp" & I don't have the weight & bigger prop penalty, plus it fits in the cowl.
With the straight pipes it barks a bit on TO but in cruise the noise isn't noticeable (in the cockpit or from the ground) & it will pull 2800rpms.
The thing I appreciate is the noticeable extra power. I'm still a rookie Cubber, but this thing makes me grin all the time.
Best example, I reckon, is that I can beat the neighbors' 0360 off the water by a full second. That's good by me!
Fuel burn, I'm told, is similar as the 0360 can throttle back a bit with a coarser prop.

[NimpoCub]

YaBut displacement = weight. Everything is a tradeoff, remember?

I wonder if somebody could post the actual weight diff between the 0320 + prop VS. the 0360 + prop??

[petez]

Best pa-12 we built had flaps was light and we put a 0290-d2b in it. was great acft. Pete

[N5126H]

I have flown a 160 and a 180 both side by side, same day, same load, same, same, same. Floats, wheels, skis. I also had the opportunity to repower with whatever I wanted. I took the 160.
I never failed to bet the same plane powered by the 180 off the water/ ground. Like I said the 180 will climb a little better, but not enough to justify the weight or cost.

I really disliked having to fly the 180 behind the power curve in order to make it do the same things.

My opinion and my money voted for the 160 and will again.

I too understand HP and why it is king, but there are exceptions and this is one.

[Scouter]

Try getting ahold of Reid Campbell at the Millinocket Maine Airport. He maintains and has flown both versions, and had some good solid opionions on both. Maybe he will chime in here as well.

Jim

[akavidflyer]

I flew a stock straight wing PA 12 150, one with flaps, and a 180HP fully bling blinged out 12 with all the Ccenter mods. Hands down the 2 150 HP lighter planes were better performers. The blinged out 12 was a brick and the 180 did not make up for the weight. Put a 82X41 on the 150 and let'er eat.

[Doose]

flew lots of hours in my 12, short crappy sheep hunting strips at altitude, hauled lots of moose meat ect. started out with a 160hp with the long mount then installed charlie's 180hp conversion and the 8.5 ft. night and day stc flap mod as far as I am concerned it was the best thing I did to my 12. There is no substitute for horsepower. Fuel burn at 2400 rpm was just under 9gph and the safety factor it gave me was priceless. True empty weight with the 180hp was 1186#

[Cubgr8]

I agree with Doose. I have never had any pilot complain to me that an airplane had to much HP. If it dose not perform with an 180 bolted to the front, it's not going to be any better with a 160 / 150 in it, it has to be light. Any Cub be it J-3, PA-18 or PA-12's have to be built light to get the best performance out of them. Nothing will beat a light, well balanced, high horse power Cub. If you ever get a chance to fly a light 180 hp powered PA-12, that is set up properly you will not be disappointed. I have built and owned numerous PA-18's and PA-12's which were powered with 0-360's and would not hesatate to due it again.

[cubdriver55]

I vote for horse power. Everyone is right here, a light 150 hp 18 or 12 will perform as good or better than a 180 at sea level on wheels. BUT on floats, at high altitude, and heavy the 180 will shine. Put a moose in the back of your 12 and take off a short gravel bar and you will see a huge difference in the 150 and 180. It is the same argument that has been going on forever light verses heavy but in the real world no one has ever paid me to fly an empty airplane. I have a 180 hp 12 with the Day and night extended wings and it is no longer a 12 anymore, it performs like a different airplane. I also have an 18 with 180 hp and stock wings and if I could do one thing to help it I would put on an extended wing with longer flaps. The wing gets you slow enough to get in and the HP gets you back out.

[pa12drvr]

Just a very tangential thought....some years back I replaced the 0-290 in my 12 with a 160 HP 0-320....before making this switch I flew a few times in 12's with 150/160/180 upgrades.

The real reason I selected the 160 vs. the 180 was nothing to do with the logic or the flying needs....I just felt uncomfortable with the way the big engine shook the airframe at startup and shutdown. Recognize that may have been the prop or whatever, but it just sure seemed to shake a lot with the big engine....so I went with the 160 horse.

[energytech]

Gained almost 60 pounds trading a Lyc O-320-A2B with 82x41 for an IO-375 B1B (Aero Sport) and MT 3 Blade prop. Prop is 55 pounds so I could have saved a bit more by using a fixed pitch in composite material but wanted some cruise. Plane is a Wag 2+2 and I really enjoy the 120' departure rolls, down from ~250'. So, if you can spare an extra sixty pounds and don't mind the seat pushing on your backside... it's great! It's also approved for 91 octane fuel. Not the cheapest route to go but a confidence builder whien operating in tight, off airport, areas.

[windy]

What's the difference, advantages/disadvantages between the Crosswinds 180hp and the univair 180hp setup for a PA-12? Doesn't the Crosswinds use a dynafocal mount, which should smooth out the vibrations? Do either or both of the 180hp STCs have approved propellers to get rid of the red arc in the middle of the rpm range?

[skywagon8a]

The shutdown shake on a 180 can be minimized by using the following: Run at 1000+ rpm, pull the mixture to idle cutoff, then immediately close the throttle until the prop stops rotating. After the prop stops, then shut off the mags. This seems to give a cleaner/smoother shutdown. I have noticed this shutdown shake on several different 180 powered airplanes and the above procedure solved the problem. All of the 180 powered planes, on which I have used this procedure, had dynafocal mounts.

[sierra bravo]

This weekend I parked my -12 next to a very attractive and obviously very newly built 180hp PA-12 that has the Univair STC. It also has the Crosswinds tail brace, flaps extended to the fuse, Cub gear, etc. I hope to run into the driver and ask about it. It's the first -12 I've seen up close with the Univair conversion and the appearance is quite similar to my -12's Crosswind 160 installation, at least from the outside. No knock on Charly's conversion but I prefer the Univair's Cub-like cowl. I'm really curious about how much it weighs. I have no doubt that it's a good performer. Nice looking airplane!

[av8rtom]

You guys are a lot of help! I'm in the middle of my 12 project and I'm starting to look for an engine and I tend to think that the more HP the better no matter what you're flying (or driving). I've done most of Charlie's mods including the long wings with really long flaps.

[adventruousairman]

Put 10:1's in the 180 and you'll never look back....just saying

[nanook]

Go with the short mount and the 160 or whatever hp 0-320... With that combo and some survival gear in the back... Makes a nice slow flying ( read "not nose heavy" ) cub or cruiser..... Pain in the arse flying a nose heavy pig around all the time....

[skywagon8a]

....The real reason I selected the 160 vs. the 180 was nothing to do with the logic or the flying needs....I just felt uncomfortable with the way the big engine shook the airframe at startup and shutdown. Recognize that may have been the prop or whatever, but it just sure seemed to shake a lot with the big engine....so I went with the 160 horse.

The shutdown shake on a 180 can be minimized by using the following: Run at 1000+ rpm, pull the mixture to idle cutoff, then immediately close the throttle until the prop stops rotating. After the prop stops, then shut off the mags. This seems to give a cleaner/smoother shutdown. I have noticed this shutdown shake on several different 180 powered airplanes and the above procedure solved the problem. All of the 180 powered planes, on which I have used this procedure, had dynafocal mounts.

This is an update on the engine shake on shutdown situation. If you are experimental go to electronic ignition such as a P-mag. I have a 180 in my Cub with P-mags and there is absolutely no shut down shake even when the mixture is pulled with the engine at idle.

[FdxLou]

This is an update on the engine shake on shutdown situation. If you are experimental go to electronic ignition such as a P-mag. I have a 180 in my Cub with P-mags and there is absolutely no shut down shake even when the mixture is pulled with the engine at idle.

Correctamundo!

[deerhunt]

Does anyone know if there is any other stc's to put a 160 hp in a -12 that is approved on floats, Crosswinds is for a land plane only.

[skywagon8a]

Does anyone know if there is any other stc's to put a 160 hp in a -12 that is approved on floats, Crosswinds is for a land plane only.

If you get in a bind you might try this approach. A friend of mine bought a -18 with a 160 limited to land only. He wanted to put it on floats. I got a field approval to derate the engine to 150 with authorization to put it on floats. All that was done was to change the rpm red line on the tach to the 150 hp rpm. With the prop that was installed it would not turn 2700 anyway. So the only thing that was changed was the red paint on the tach.

[deerhunt]

Thanks for the reply, I forgot to mention I am in Canada, and trying to deal with TC on this would be a lot of hassle and maybe money. Might just stay with the 150.

[NimpoCub]

Talk to Scott McNab (TC Inspector) in Kelowna, BC. He's VERY knowledgeable & HELPFUL. scott.mcnab@tc.gc.ca (250)491-3703