Hey all,

I am faced with an engine that has decided to send itself to pasture, so to speak. The airplane in question is a 1961 C-185 that currently has an IO-470 installed. There are a few options, overhaul the 470, or swap to a 520 or 550. Due to cost differences and several other factors, the 520 doesn't seem like the road to follow. That said, do any of you all have experience with an early 185 IO-550 swap? Have any of you flown both a IO-470 then an IO-550 powered early 185? There are lots of factors at play here that are difficult to wrap a brain (if I had one) around; it would be great if there was some real world experience out there willing to share a few minutes of typing.

The 550 is looking like it will cost around $35K more than an overhaul of the current engine (new prop, engine mount, blah blah blah). I know, that is a phat pile of cash. However, barring some unexpected wild life changes we plan on keeping this airplane for many years to come. This in mind, the cost difference is tolerable assuming the swap is worth it. So there is my question; if you have some experience with these swaps, would you do it again? What was the biggest pain? What were some unexpected hurdles or benefits? Any information would be greatly appreciated, as the more I dig into this, the more it seems to be an unknown...other than to date I have operated lots of machinery with enough, but NEVER too much power. Word vomit away, I appreciate any and all experience/thoughts/wild ideas.

PM sent.

MW

I do not have experience with a very early IO 470 185 swapped to an IO 550.

But, I have flown IO 550s, and to be blunt, that is the engine that EVERY 185 wishes it had. The difference between the 550 and ANY other Continental is significant. Lots of power, cool running (when set up right), the LOVE running Lean of Peak EGT, so burn less gas, and they are smooth!

I could go on, but I very seriously doubt that you could ever regret installing a 550 in that machine.

A 520.....probably not that much gain.

MTV

Although not specific to your engine choices, I will share my thoughts when faced with re-power decisions. It is human nature to always desire more. And yes, who does not desire more power, especially when operating on floats and skis. I have been faced with your conundrum several times with several airframes, two of these when deciding to overhaul the O-470R in our 180H. I was working our 180 at those times, mostly on skis, nearly always at gross (3190). The three factors that drove my decision were 1) Can I accomplish the mission with this equipment, 2) Reliability, and 3) Maintainability (supportability). In over 3500 hours of fairly severe operating conditions, the R model never let me down and the answer to my three conditions was a resounding YES. Therefore, I chose to keep that engine and operate within its limitations.
One more example that went the other way. When we purchased our PA-18A it was powered by an O-290D2. This combination was not capable of meeting my mission requirements at high altitude and weight requirements; therefore, I installed the right "tool" for my specific mission which is an O-360.
Properly maintained, a piece of equipment will always do what it was designed to do. Problems occur when we unfairly compare it to something else (usually more powerful) and ask it to perform in a manner for which it is incapable. My examples were driven by a requirement. Even if you are not working your 185, you still have it for a purpose, therefore, the answer lies in what best meets that purpose. Or perhaps you just want the larger engine, which is a valid reason in itself.

TR

If you operate on floats the 550 will feel like you doubled the HP. MTV's comments will seem very conservative. Its a great engine. The 550 and voyager will turn it into a fire breather and will cruise at an easy 130K on floats. My friend just did same to his 61. He has been in commercial float operations since he was a kid and operated every single engine floatplane from a Norseman up and can't believe the performance. We have had 550's in 185's and running one in a 182 now and its been all good.
The bad news is from a resale perspective is that $100K by the time you are done is better spent on a late 70 early 80 low time aircraft. Depends a lot on how long you plan to keep it. No matter how much you spend on avionics, paint, interior etc the 1961 number will limit your resale compared to the F models.

Thanks all for the comments. What you have said is what I expected.

mtv, your comments echo many others I have heard. I assume the performance would be impressive.

TR, I appreciate the logic you have bestowed via your comment. You're 100% correct. I feel as though we often take what we have and attempt to make it into what think we want/need as opposed to learning to utilize it as it, often times learning we should have just bought something else. Then again, sometimes we need those lessons I guess.

Peter, the cost vs. value is something I have been rolling around in my head over and over. It can be astonishingly costly to modify our airplanes, only to roll out the other side with a machine thats worth exactly what it was before. I guess there is some passion involved, otherwise we would probably all not own airplanes. Addiction is hard to break!

Jury is still out, but thanks for your thoughts. Every little bit helps.

If you have the money - the answer is a simple yes. I haven't flown an early Model 185 that went from an IO470 to IO550 but I have flown a 550'd 185F model. The IO550 on an early lighter 185 would make it an absolute monster. I think the weight difference isn't that much more either. Of course money, parts, and downtime are all going to play a part. I went from an O470 to O520 in my 58 C`180 back in 2007. Couldn't believe the change in performance. The IO550 is overall a better and cooler running engine than the 520. The difference between the IO520 vs IO550 would favor the bigger engine. I don't think there are any unhappy 550'd C C185 owners.



Josh

To add to the comments on the 550, compared to the 520:

The 550 makes an honest 300 horsepower at 2700 rpm, compared to the 520 maybe making 300 hp at 2850 rpm.

While the 520 with GAMI injectors runs Lean of Peak okay, the 550 loves to run LOP. I ran them at 13 to 14 gph, running CHTs around 320 to 330.....a very happy engine.

And, for reasons I can't explain, every 550 I've flown seemed significantly smoother than any 520 I've flown. That may be my imagination, but.....

MTV

Just finishing installing a LyCon rehabbed 550 in a 61: serial 0237 the last "non A"...
I will say the conversion is not a walk in the park; induction, fuel pumps and various other small -but many change outs make it more complex. I have 2500 hrs behind a Texas Skyways 550 (carbed) in a G 180 and it was a great change. Agree with MTV smooth...but engine mounts make a big difference too.

I fly a pretty heavily modded 550’d 185 swinging a Black Mac and been in several other wagons of varying setups, down to the stock 0-470. I’m definitely not an expert but if in fact you can upgrade to the 550 for only 35K more……….thats a no brainer. Your wagon value delta will go up more than that verses the overhauled io-470. Not sure if you’ve accounted for a new prop or if you’ll need it depending on what you have now. I flight plan for 140KTS between 8-12K burning 12.5 an hour roughly. The 550 is the engine the 185 was designed to have. I’ve flown mine heavy, probably not at gross but within 100 pounds, and all I can say is daaaaamn. There is ALOT of grunt power there. You don’t stay in ground effect, when it lifts off, your climbing. The WING X and SPORTSMAN are contributing to this ALOT as well. I’ve never been in another 550’d wagon, but I’ve read other people comment on how smooth they are………ya, that very accurate. My setup is extremely smooth.

I REALLY like it if ya can’t tell.

You will very much appreciate going from an IO470 to an IO550 on a light airplane like a 1961 Cessna 185.

I was not impressed with the performance of our IO470 powered 185, it didn’t feel like it had a lot of bite. It could have been the MTV15, as my old 182 with and O470 really blew it out of the park with it’s Hartzell 8068 Top Prop.

My current airplane, a Cessna 310R has had the IO550 swap, and they’ve been phenomenal engines. My factory remans are from 2001 with 2000+ hours on them without a single hiccup other than vacuum pumps, a starter or two and a now an intermittent generator that I’m currently troubleshooting. Reliability has been phenomenal. Performance has also been phenomenal. The IO550 is a winner in my eyes. Always puts a smile on my face!


The early 185s are eligible for two IO550 STCs. The Texas Skyways and the Davis Aviation conversions. I talked to Wipaire a few years ago about having them fix all of the mistakes that were made on our airplane during its “rejuvenation”, to also include an IO550 and they said that they are working on expanding the AML to include the earlier airplanes. Doesn’t look like it’s been added just yet.

Donna has been an absolutely wonderful resource. When it’s time to deal with our basket case, I think I will be using the Davis Aviation STC.


To play devils advocate, one thing that I’ve been thinking about is finding someone that is doing the IO550 upgrade who has an IO520 with lots of life to give. You could send the IO470 in as a core and be into a bigger and better engine for significantly less. The other benefit is that the IO520 conversion is a little bit simpler than the IO550 conversion. Engine upgrades have been on the back burner since the fire, but I have a ton of notes on the subject and I’ll look for them.

I thought I would chime in on how wonderful Donna is and I have known here 30 years from Bonaire (Pre Davis) days... I used the Davis STC for my 61., as I said the devil is in the details, of which there are many in the swap, but Donna knows her stuff and other early airplanes that have had the change over. You won't do better.
Nothing negative about TS I used Jack's STC on the 180G to carbed 550 and it was awesome.

Thanks again for all the info guys, you have helped make this decision a little easier.

As far as engine mount...is the Seaplanes West mount worth it? Currently have a Cessna seaplane mount installed and the Davis conversion does not require a new mount regardless of what is installed. My monkey brain says that it is probably worth the new mount, but if you all have any real info to share I would love to hear it. The SPW swap is not an insignificant sum of cash.

Thanks again.

I can’t comment on the engine swap, but my 520-powered 1981 model is turbine smooth with the SPW mount, LOP or ROP. Maybe it’s the mount, or maybe I just got lucky.

Giving up the utility of the swing-down mount for maintenance versus the "turbine smooth" SPW mount is a real tough question for sure. Customers I interacted with in the seaplane 185 world thought the SPW mount on a fresh 550 was totally worth it, very smooth. Of course they weren't the ones working on the back of the engine...

Not knowing the history of your current mount but if you do decide to keep it an overhaul is a real good idea. I've seen one older mount snap a tube after installation of a 550. Maybe send it to Acorn Welding have them "repair" it to include the giant rubber isolators on the SPW mount?

Best of both worlds, swing-down and turbine smooth...

Someone mentioned it above, but I have a io520 with 850 hours and clean oil analysis. Has flown hundreds of hours the past two years. I’m going to be looking for a buyer shortly.

I have a 550 on order and it will get strapped up there.

If you want it, let’s chat. I’ll be needing a core as well.

Once you go 550, you never look back!

You say the price delta between the 470 and 550 is roughly $35k. If you went with a 520, where would that fit, price-wise? Could you keep your current prop with a 520?

SPW mount. It’s an incremental cost in the grand scheme of the upgrade Pat. Talk to Donna.

MW

Well if anyone is interested (or bored and just want to read something),

We made a choice and the airplane is flying again. The old prop (C230 2 blade 88”), engine (IO-470) and engine mount came off. A new SPW engine mount, IO-550 and Hartzell Voyager was installed. All I can say is wow. First break in flight was run at 21” and 2500 rpm (72% power…field elevation is almost 7000ft so making power is a bit of a challenge) and she ran around in a circle about the airport at 160-165 KTAS. Fuel tanks will pay for that speed, but not bad for a wagon.

For anyone considering this, the project was certainly more than an engine swap. Not impossible, but not quick. Was it worth it? After about 10 minutes of flying that answer was a resounding yes. Feels like a new airplane, lots of power, remarkably smooth and still under 1800 lbs.

Donna, of Davis aviation, could not be more helpful, knowledgeable or nice. Most people in this business are good people, but she really is great. If you want a bigger engine in your Cessna, she is a pile of information.

Appreciate all who chimed in, your thoughts were all considered and helpful.