O-550

I'm wondering who (if anyone) has an STC for a carbureted 550 Continental on a 180?
The XP470 (aka 470-50) is such a popular, an O550 seems the next logical step up.

Texas Skyways.

Yes, thanks, just googled that one up myself.
I thought maybe Ponk had an STC but apparently not.
I think he did at least one on a field approval though.

Texas Skyways are great people to do business with. I bought the IO-550 for my 185 from them. :smile: :smile: :smile: Very smooooth.

skywagon8a said:

Texas Skyways are great people to do business with. I bought the IO-550 for my 185 from them. :smile: :smile: :smile: Very smooooth.

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I will second Texas Skyways as a great place to deal with.

aktango58 said:

I will second Texas Skyways as a great place to deal with.

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I'm interested as to what the fuel consumption of a carbed O-550 would be to get a reasonable rich of peak . I know my carbed 0-520 had a way higher fuel flow requirement before I went fuel injection. Back when the IO-550 came out we joked they were liquid cooled, and the liquid was aviation gasoline.

bubb2 said:

I'm interested as to what the fuel consumption of a carbed O-550 would be to get a reasonable rich of peak . I know my carbed 0-520 had a way higher fuel flow requirement before I went fuel injection. Back when the IO-550 came out we joked they were liquid cooled, and the liquid was aviation gasoline.

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The IO-550 on the 185 would drink in the 25 gallons an hour on takeoff as I recall, and around 22 in climb at 25 square.

Cruise was around 17.5, if at 6,000 I got it down to 16.5 sometimes.

Less than that and things did not go well.

Carb? Add a gallon an hour for each maybe?

The IO-550 in my 185 at 24/2400 uses 15.8 gph rich of peak with balanced injectors. The turbo TSIO-520 was 17.8 at 24/2400. Any less was trouble.

skywagon8a said:

The IO-550 in my 185 at 24/2400 uses 15.8 gph rich of peak with balanced injectors. The turbo TSIO-520 was 17.8 at 24/2400. Any less was trouble.

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I never checked our fuel flow for accuracy down to the last gallon, so maybe she did burn less. I also don't know if we had balanced injectors. I do know when they ran her in lower fuel burns things did not go well.

I wonder how much difference balanced injectors would make? I imagine quite a bit on that size engine.

Fedex Lou had an 0-550 is his old 180. If somebody wants real numbers for a carb’d 550 he’s who I’d ask. That he now flies a light early model with a 470 is worthy of mentioning.

We changed a lot of cylinders on the IO-550’s. The owners were alway looking to get better fuel economy, my guess is they were running to hot. My thought is being sensitive to heat , going with a carb is going to unbalance the fuel flow and make it easy to cook cylinders. We changed 3 to 1 cylinders vs the IO-520’s..

I ran an IO-550 in a 206 over a thousand hours and nearly always ran it LOP, burning 13.3 to 13.5 gph. This is at relatively low power settings, but Continental prohibits leaning that engine at higher power settings. Balanced injectors and good engine monitor, including fuel flow instrumentation.

I ran 65 to 70% power and that thing just sipped fuel. Great engine. But, I’ve never run a carbureted version....would burn a lot more gas, methinks.

I loved that engine, buckets of power when you needed it, but low fuel flows enroute.

MTV

aktango58 said:

I never checked our fuel flow for accuracy down to the last gallon, so maybe she did burn less. I also don't know if we had balanced injectors. I do know when they ran her in lower fuel burns things did not go well.

I wonder how much difference balanced injectors would make? I imagine quite a bit on that size engine.

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This engine came from Continental with the balanced injectors so can't say what the difference would be. I did move the injectors around in an attempt to refine the EGTs. Continental had them correct in the first place.
Leaning to LOP reduced the power and lost airspeed. Past history with the IO-520 taught me that indicated airspeed above 110 knots was mandatory for enough cooling ram air. An extra 1 gallon per hour ($5) saved cylinders. This one indicates 121 knots in warm weather, higher this time of year. Lots of cooling.

I'll take the efficiency of the fuel injected big Continental over the inefficient carbureted version any day. The IO-520 in the 185 is more efficient than the O-470 in the 180. The IO-550 in the 185 has lots of power for when it is needed, does burn more fuel in cruise but is faster. Reducing power to IO-520 fuel burns reduces the speed to IO-520 speeds.

Pete,

Does your 550 still have the altitude compensating mixture? Ours had been removed and manual mixture .

Our conversion (Wipline) had a restriction on leaning above a certain percent power. Running LOP on that engine was smooth, and CHTs ran in the 315 to 330 range in cruise.

Loved that engine, but I sure wouldn’t put a carb on one.....

MTV

Mike,
It has an altitude compensating fuel pump. When operating at full power the pump pressure is compensated for altitude. The mixture control is conventional manual operation. The placard for full power fuel flows is removed.

It is smooth LOP, along with a power loss with the lower consumption which resulted in lower IAS. Cooling being dependent of ram air through the engine, I prefer the higher IAS.

algonquin said:

We changed a lot of cylinders on the IO-550’s. The owners were alway looking to get better fuel economy, my guess is they were running to hot. My thought is being sensitive to heat , going with a carb is going to unbalance the fuel flow and make it easy to cook cylinders. We changed 3 to 1 cylinders vs the IO-520’s..

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That falls under "Stupid Pilot Tricks" category.

We had a couple cylinders go early on. Our mechanic took a ride with me watching fuel flows, then went back deep into the books and adjusted fuel flows internally for more fuel in high power settings. Never another issue.

Seems the problem is guys think the 550 is just like a 520 and should burn the same amount of fuel, so set up the fuel control or lean it like a 520. Results are expensive.

As far as Lou's 180, if you flew it you would tell him what I did: Don't mess with it. It flies like a dream. Adding nose weight would make it much less docile in my opinion.

algonquin said:

We changed a lot of cylinders on the IO-550’s. The owners were alway looking to get better fuel economy, my guess is they were running to hot. My thought is being sensitive to heat , going with a carb is going to unbalance the fuel flow and make it easy to cook cylinders. We changed 3 to 1 cylinders vs the IO-520’s..

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Often times people set the TO fuel flow to low on these and the 520 engines. At max power during takeoff there is a ton of heat generated, the only thing to keep them cool is fuel.

behindpropellers said:

Often times people set the TO fuel flow to low on these and the 520 engines. At max power during takeoff there is a ton of heat generated, the only thing to keep them cool is fuel.

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The instructions in the Continental manual are very clear on how to set up the two fuel pressures. I installed two fuel pressure gauges in my 185 so that both pressures can be checked on each take off.

Our maintenance folks set the fuel flows higher than recommended in Continental's paperwork, on the suggestion of a Continental Tech Rep.

The early 550 conversions in 206s stepped cylinders at anywhere from 700 to 1000 hours. Those cylinders were then junk. These engines weren't being abused, near as I could tell. We had one of those 206s, and it had lots of cylinder problems. CHTs ran VERY high, even in cool temps. When I was assigned a 206 with a new 550, I was concerned, and called Continental tech help and asked what I should do. The rep told me to get the serial number of the engine and call back. I did, gave him the serial number. His response was "Don't worry about it....just operate it per the book and enjoy."

That engine, compared to the early one in the other 206, ran remarkably cool CHTs, even in very warm OATs and on floats. I called the Tech Help back and asked what had changed. His response was essentially a smile.....they changed something, but wouldn't say.

Later engines also ran cool.

MTV

Just 2cents worth from my experience and observation.
The Cessna FF gauge as we all know reads fuel pressure calibrated for FF, not actual FF. I have a JPI 700 and a JPI FS 450 fuel flow gauge in my C-185. I wouldn't fly without them or an upgraded version.

Recently I had an experience that brought to my attention, in what could have been a very dramatic way, the advantage of these two gauges.
I was doing some dual in a friends 185. On take off the Cessna gauge read around 28GPM but it was obvious that something was wrong from the lack of normal acceleration. The FS-450 was indicating around 17-18 GPH The egt's were hi-lo across the 6 jugs. We were still very slow, around 40Kts when we aborted, so no big deal. We took it back to the FBO and I told the mechanic I suspected there might be some blockage in the spider assembly which could account for the discrepancy. It was found out indeed to be contaminated.

There are several takeaways here but here are two that made a lasting impression.

The installation of a real FF gauge is money well spent and potentially lifesaving.

The pilot is fairly low time 200hrs TT, and 120 in the 185. He did not recognize something was wrong till told him to abort, twice.
Both the JPI EDM gage and more importantly the FS-450 FF gage were telling us something was very wrong. The good old Cessna gage was saying everything is AOK.

Something to think about.

I had a Texas Skyways 0-550 in a 182, no problems, loved it

a3holerman said:

The Cessna FF gauge as we all know reads fuel pressure calibrated for FF, not actual FF.

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John Steer taught me that WAY back in A&P school. Not sure how that system was ever certified but now we have to live with it. As 3holer said above, get a direct reading fuel flow instrument to get an accurate reading of the system at all power settings.

Web

I flew an A36 for years that had an IO-550. ROP it would burn 17-17.5. LOP it would do about 13.8 to 14.5. Forget offhand what power settings, I think we just left the throttle wide open and pulled the prop back to 2500.


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