Hey everyone,

For those of you with experience running the IO-550, I'd like to get some information. If ran correctly, anyone have a history of running them beyond TBO? I know they burn more fuel and cost more to overhaul. What kind of numbers do you see in day to day operations? LOP or ROP? Finally, any quirks specific to that engine? Any big do's and don'ts?

Thanks,
Cory

Lots of Bonanza guys run the 550. LOP is the way to go.

+1 on the LOP
It's the way to go, runs very smooth and cool mine is an N with the tuned intake.

What airframe? I just started flying a 185 with a -D & it's pretty impressive. Have about 20hrs in it sofar so I can't answer the questions, but I'll be following to see what the experts say. Have only ran ROP sofar, whats the fuel burn if you go LOP?

Flew my GF & her friend over to GRB today, for the Packer game tomorrow night. 160 IAS at 6500' & 21 degrees OAT, think she's going to freeze her butt over there tomorrow. Lol

Grassstrippilot wrote:Hey everyone,

For those of you with experience running the IO-550, I'd like to get some information. If ran correctly, anyone have a history of running them beyond TBO? I know they burn more fuel and cost more to overhaul. What kind of numbers do you see in day to day operations? LOP or ROP? Finally, any quirks specific to that engine? Any big do's and don'ts?

Thanks,
Cory

You get a 205 with a 550 in it Cory?

Going to go look at one. Yes, a 205. No GAMI's or engine analyzer...yet...so ROP is the only option for now. But I'd also like to know what fuel burns you guys are seeing both ROP and LOP.

Thanks,
Cory

LOP around 11.5-13 depending on altitude.
12.5 at 10,000 and 300-315 CT's

I ran a 206 with 550 1800 hours or so, almost all LOP...planned 13 GPH but that was mostly on floats.

Fantastic engine...MUCH better than the IO 520, in my opinion. TBO is higher and they'll go there.

BUT READ the power section of the engine book.....some of these engines are not to be leaned AT ALL if you're running more than 70 or 75 % power. You'll burn cylinders if you do so.

Because rated continuous power is 300 (as opposed to 285 for the 520) you can't use the same rpm/mp settings in the 550 as you would in the 520.

But, the 550, run according to manufacturers recommendations, is a fantastic engine.

MTV

Grassstrippilot wrote:Going to go look at one. Yes, a 205. No GAMI's or engine analyzer...yet...so ROP is the only option for now.

Thanks,
Cory

I wouldn't go that far. I have no GAMI's or an engine analyzer either and she runs great LOP. The fact of the matter is the fuel flows for a given operation are not a moving target. I have three main cruise setups. 19"/2100 and 8.5 GPH for local area flying. 23 squared at 12.5 GPH, I use this the least. WOT/2500 at 9500 and above leaned to peak which will be about 12 GPH.

mtv wrote:
BUT READ the power section of the engine book.....some of these engines are not to be leaned AT ALL if you're running more than 70 or 75 % power. You'll burn cylinders if you do so.


MTV

For the really interested go to the APS website and sign up and you can take a test they give to their students before they start the class. http://www.advancedpilot.com/freesignup.php It's free and will challenge everything you think you know about engines. Burning up cylinders on a 550 at 75%? You were doing it wrong. These guys as well as the GAMI guys will show you how to run your 550 at full power LOP during climb as well as break in your engine LOP. Take the test.

Just put a 550 in my Bonanza this spring. I have GAMI's, and engine montitor (EDM 700), and D'Shannon engine baffling. I run rich of peak at about 18 gph and lean of peak at around 13 gph depending on altitude. I run lean of peak almost all the time. CHT's are around 350 and EGT around 1450. I replaced a 520 that I had put 1800 hours on. So far I really like this engine. I'm getting quite a bit higher TAS (174 knots LOP and 180 ROP new engine vs 160 knots LOP and 174 knots ROP old engine), much better takeoff and climb performance. If you go with a 550 make sure to get the D'Shannon baffling, it make a big difference in cooling!

Bonanza Man wrote:

mtv wrote:
BUT READ the power section of the engine book.....some of these engines are not to be leaned AT ALL if you're running more than 70 or 75 % power. You'll burn cylinders if you do so.


MTV

For the really interested go to the APS website and sign up and you can take a test they give to their students before they start the class. http://www.advancedpilot.com/freesignup.php It's free and will challenge everything you think you know about engines. Burning up cylinders on a 550 at 75%? You were doing it wrong. These guys as well as the GAMI guys will show you how to run your 550 at full power LOP during climb as well as break in your engine LOP. Take the test.

BM,

I've read all the stuff those folks put out. I've also read the engine operating instructions for the flavor of 550 that I ran, and Continental specifically states DO NOT run the D engine with mixture leaned above 75 % power. GAMI doesn't warranty my engine..Continental does.

And, yes, you are correct that the dipshit that used my airplane for 25 hours didn't do it right....and fried two cylinders...because he was trying to run it at rpm/mp settings he was used to on a 520...ie: leaning it above 75 %.

I try to abide by the manufacturers recommendations most days. And while graphic engine monitors aren't necessary to run LOP, they sure make a lot of sense for diagnostics on these expensive engines.

MTV

Finally, why the heck would you want to run one of these engines that hard anyway? They sing at 70 % and LOP.

It's a higher time engine and I'm curious if guys are running them beyond TBO. Obviously it depends on how the engine was run and I'd want to have the engine checked as thoroughly as possible. On our club planes, we routinely run them beyond TBO (O-470s and O-320s) so long as they aren't making metal and compressions/borescopes are good. We also do oil analysis as well. Typically we run them to 3000 hours if all is well.

BM, I didn't mean to imply that GAMIs and an engine analyzer are required. Personally, though, I want them (specifically the analyzer) before I run LOP.

Thanks for the info guys!

In my opinion I would NEVER run any engine LOP. A lot of people out there swear you can, but I wouldn't gamble the life of my engine just to save a few extra gallons. It's just not worth it and if you can afford the 550 conversion than what's an extra couple gallons of fuel?

N300RE wrote:In my opinion I would NEVER run any engine LOP. A lot of people out there swear you can, but I wouldn't gamble the life of my engine just to save a few extra gallons. It's just not worth it and if you can afford the 550 conversion than what's an extra couple gallons of fuel?

The 550 will run cooler and last longer LOP
I think u just need to research how its done but if u want the super simple cant mess it up approach

It's this:

Climb to 10,000 ROP then lean to 12.4 gallons per hour or less
Puts u at about 65% power and u just can't really hurt it there.

N300RE wrote:In my opinion I would NEVER run any engine LOP. A lot of people out there swear you can, but I wouldn't gamble the life of my engine just to save a few extra gallons. It's just not worth it and if you can afford the 550 conversion than what's an extra couple gallons of fuel?

There is no more danger in running an engine at LOP at any power setting than ROP. Assuming that you are really over on the lean side.

The danger is running it just rich of peak actually, something that a ham handed knucklehead is just as likely to do trying to attain his "usual" rich of peak setting as he is trying (and failing) at the correct mixture for LOP ops.

Your cylinders don't care what the EGT is anyhow. Run it wherever the heck you want at high power and watch the CHTs, or run it at lower power and don't worry either.

It's been shown that you can not only do LOP operations, but that it isn't harmful to the engine when done properly. So, why not treat the engine well and save on fuel? Of course, the operator has to do the research, learn how to do it, and be willing to accept that much of what we thought we knew about engines (like 50 ROP) was simply wrong.

As already posted, the IO550 is the way to go hands down! -520 doesn't even come close. More power you can feel for t/o, smoother. Torque peak is 2400rpm acording to the Continental engineering rep, so it can pull a big prop at a slower more efficient speed. Make SURE that the fuel flow is set for 30 gal/hr at full power sea level or you will be one of those whiners that claim the engine is junk and burns up cylinders. It loves LOP at lower power settings. I run my 185 with the 550 at 21 inches/ 2300 rpm / 12.5 gal. Hr. Speed depends on config and alt. The plugs are always clean and the cylinders borescope real nice with good numbers. Once you go 550, you will never go back! Worth every dime!

Thanks Rock Hopper and everyone one else. Guess we'll see how the planes look that I'll be seeing the next week or so and go from there.

What's an overhaul cost these days on a 550?

The IO-550 is the best running piston engine that I have flown, out of at least a dozen others.

I am a believer in the lean of peak philosophy. The CHTs are lower and there are almost no carbon deposits in the combustion chamber after many hundreds of hours. This method is easier on the valves, will virtually eliminate the possibility of detonation, and you can save a considerable amount of fuel while you are at it.

I would be comfortable running lean of peak without an EGT gauge by understanding that there is a "hump" on the EGT/mixture graph, and you need to pull the mixture through the high region from ROP to LOP. After you are over said hump, all of your engine temperatures are decreasing. The lean until it runs rough and enrichen slightly technique is acceptable in a naturally aspirated engine, where high EGTs and Turbo inlet temps are not detrimental. I still have yet to hear a convincing argument for ROP operations. Continental encouraged LOP ops on the Lancairs and Columbia 300,350,and 400 models, which I have flown for years. "That's what I was taught" isn't convincing to me.