Thanks for posting up John! I know what it is like when you end up living at the shop

Being that you have done an o470, and I believe I read you did an o360 at one point, what would be your preference for a build?

I didn't even get to the shop! We had a foal born and he didn't want to nurse, so we were up feeding him every half hour for a few days and then every hour for the rest of the week. Finally got the chiropracter out and he worked with him and he's able to nurse now...

My true preference would be the IO-390. If not that, It'd probably depend on the mission. The 360 is going to be lighter, and combine that with a good lightweight airframe, and it'd be hard to beat!
At one point, Charly Center did some work with a leading edge cuff on the Stinson with an O-470. I saw the flight test report and it was unbelieveable! It would not power on stall. If I remember, it would fly about 30mph and climb at 500' a minute at gross with everything out and back. They had a heck of a time trying to get it to spin. It was always my dream plane to try to come up with that combination. I also think with an MT prop, you'd drop a bunch of lead off the tail and other stuff. The downside of an O-470 to me is that they're pretty tight to work on behind the engine, but you really don't spend that much time there to be realistic.
Either will be a great performer!!!
John

TheMachinist1 wrote:
I did hear from one guy with the 200hp io360, and he says he can climb out at 1400fpm, overgross, on a hot Florida day. I am skeptical of that, as that is more than double the rate with the Franklin 165 with climb prop.

I'd love to hear from anyone operating aircraft in these power ranges and empty and gross weights.

I've got a -3 with the IO360 and in MT at 3300' in the winter I'm seeing 1200fpm every flight climbing at 90kts indicated. Even at 10,000' I'm getting better than 500fpm. That's with me and full fuel. Empty weight ~1470 lbs as calculated, will update when I get it weighed at annual.

TheMachinist1 wrote: I'm in Canada and we have a STC here for the o540. ....

I'd be interested in hearing more about that STC.
A guy I know has a (very long term) Stinson project that he's gonna put an O540 on.
Actually, two- his & his buddy's.
He told me someone makes the mounts but they don't have an STC, so installation requires a field approval.

I've seen hotrodded Stinsons with a wide variety of engines: Lyc O360, Lyc IO360, Cont IO360, Cont O470, Lyc O540.
I just met a guy a few weeks ago that's got one with a 220 Franklin, and a Charley Center / Crosswinds STOL leading edge cuff.
I've known a couple guys that owned 470-powered 108's, that's the way I'd probably go--
but then again I'm a Cessna 180 guy so I may be a little biased.

Hotrod - This is the O540 STC we have in Canada http://www.hangar9aeroworks.com/stinson ... 540STC.pdf

John - What was the reason for the extra stringers in the belly on the o470 conversion you did?

I did a quick spreadsheet comparing the the engines I am interested in for the 108-3, as well as some other commonly compared 4 place aircraft. It's just weight and power loading, which doesn't give the full picture, but it is better than straight hyperbole

I’ve been looking at many of these options as well. The one that looks best to me would be the Continental, I have been trying to track down the IO-360 STC for the Stinson. I have run in to a dead end. Does anyone have any information on that? Or maybe knows someone who has that engine installed? Very frustrating, it’s a great machine, just needs a bit more power.
In the meantime I may send my Franklin cylinders off to Airworx for porting and polishing. He just got a new flow bench , should be able to add some substantial horsepower to the Franklin for a reasonable price.
Thanks,
Dennis

Having flown both 0360 and 470 conversation, on the Stinsons ( as well as Lyc 0435 with 2 position prop) The 0470 has brut force advantage's on floats, with a noticeable
ROC edge. BUT: it was nose heavy as heck and
would NOT fly nearly as slow on final. You are constantly out of fuel with the 470...
An 0360 is the perfect balance for the Stinson
A ported 200hp one would be sweet. Only flew
The 0360 on wheels but it was a dream to fly and performance was very similar to the C170B with an 0360. Or even the Maule Mx7/0360 another nicely balanced airplane compared to the 540 big brother.
For an all around machine it would be my opinion the 0360 is the best option.....
Good luck
E

107ch wrote:I’ve been looking at many of these options as well. The one that looks best to me would be the Continental, I have been trying to track down the IO-360 STC for the Stinson. I have run in to a dead end. Does anyone have any information on that? Or maybe knows someone who has that engine installed? Very frustrating, it’s a great machine, just needs a bit more power.
In the meantime I may send my Franklin cylinders off to Airworx for porting and polishing. He just got a new flow bench , should be able to add some substantial horsepower to the Franklin for a reasonable price.
Thanks,
Dennis

Lake Clark Air and The Farm Lodge in AK operate a very modified 108 with Cont IO360, and one of the senior employees (my boss) also owns the tundra hawk STC.

They aren’t really wanting/willing to do anything with it as far as I know - there’s no money there.

TheMachinist1 wrote:
John - What was the reason for the extra stringers in the belly on the o470 conversion you did?

One of the biggest problems with the Super Stinson on floats was the prop blast beat the fabric up pretty bad. Extra stringers helped out quite a bit. If I was to do another one now, I'd double cover instead.

There's a couple guys, Herk Stumpf being one, that are supposedly close to getting approval for the O-540, based on the Canadian STC. Ken Brock had a beautiful -3 with one in it, a long time ago, but on a field approval.

Glen Alsworth might have more info on the Continental IO-360 STC. If I remember, he's got a -3 with one.

John

107ch - The Continental engine is an sweet option, light weight and good power. No mogas though, so it's out for me. I added it, along with the Franklin 220 and o470 in the -3 to the spreadsheet:



TurboBeaver - Thanks for the feedback. The o470 is not an appealing set up for me. As I understand it, they require ballast in the tail to try and get the CG manageable, and the setup is a good bit heavier than an o540, while making less power.

I really like the idea of keeping the bird light, and the idea of the o360 is very appealing for that reason. If I was flying mostly myself or just 1 other person, low gear and low fuel I think it would be a no brainer. Unfortunately I often fly quite heavy, and that has me considering the o540.

I'd love to hear more experiences!

Thanks for the explanation John, I'll keep that in mind when I re cover it.

TheMachinist1 wrote:107ch - The Continental engine is an sweet option, light weight and good power. No mogas though, so it's out for me. I added it, along with the Franklin 220 and o470 in the -3 to the spreadsheet:



TurboBeaver - Thanks for the feedback. The o470 is not an appealing set up for me. As I understand it, they require ballast in the tail to try and get the CG manageable, and the setup is a good bit heavier than an o540, while making less power.

I really like the idea of keeping the bird light, and the idea of the o360 is very appealing for that reason. If I was flying mostly myself or just 1 other person, low gear and low fuel I think it would be a no brainer. Unfortunately I often fly quite heavy, and that has me considering the o540.

I'd love to hear more experiences!

Thanks for the explanation John, I'll keep that in mind when I re cover it.

Are you staying certified with the bird? If you are moving it over to amateur built I would suggest looking at something like the aerosport 0-375. Ported and polished you'll be running in the 215hp range. Heck of a hard pulling engine as well. One of my customers is running one on a bushmaster and it works very well.

Yes, the bird is staying certified, and I need to run mogas, so that limits the options.

TheMachinist1 wrote:Yes, the bird is staying certified, and I need to run mogas, so that limits the options.

I believe the Lycoming 360 requires 91 octane mogas per the Petersen STC.
There are several varieties of O540 Lycoming,
Petersen indicates some require 91 but some are OK with 87.
Depends on compression I suppose--
I think the 235hp version would like 87.

The carburated 8.5:1 o360's (180hp models) and 8.5:1 0540's (250-260hp) all require 91 octane or better. Luckily Petersen has STC's for the engines, and the only ethanol free mogas I can get in my area is 91 octane.

After reading this thread, and looking at the loaded numbers, I'm really starting to lean towards bucking up and just putting the money into an o540...

https://backcountrypilot.org/forum/maule-m5-11590

I recently installed an IO-360 A1A with an 80 inch MT prop and Lithium battery. My 108-3 has the Razorback covering which add a little more weight that your standard covering. My empty weight is 1423 pounds.

I know several people with the O-470 and I perform just as good as they do plus burn less gas and have 150 lbs better useful load.

I have a friend that has a 170B with the continental IO-360 210 HP engine and out perform it in every category except top speed and he is about 5 KTs faster and that IS the only area where he out performs my 108.

I know 6 people that have the same conversion as me and I out perform them. The reason? the MT prop

The MT prop is awesome all though it took me 366 days to get it approved.

Hope this helps

Steve

I have a 108-2 with the Franklin 180, this plane is an absolute beast!

Full fuel and baggage and it’ll still perform as well/better as the 180hp CC-18 I fly, and faster.

Having owned a 108 for a while I’d highly recommend on not metalizing I or adding a heavy engine or prop

One of the beauties of the plane is how it handles, and it’s such a sweet flyer

I debated tossing a huge engine in mine, full IFR, etc, but it would kinda kill the Cadillac ride it is famous for, plus how smoooooth it was

Ended up just getting a 185

IMHO don’t try to turn a plane into something it’s not

More power is better, but not at the sacrifice of weight and the balance of how she handles

Good example, flew a early model 182 with 550, climbed and cruised nice, but it handled and landed not as nice

A fabric 180hp conversion would be nice

But much more than that and it’s probably not going to handle as well as it used to

For what its worth I had a 108-2 with a 0-470 for several years and liked it very much. Was relatively fast and easy to fly.
Tom