IO550 vs Cirrus installation

Ted DuPuis said:
My point was that you said the modern marine engines are sold as "run however you want, they're good for X amount of fuel." In an air cooled piston, I could run it exceedingly poorly and I could get way less life out of it, at least out of the cylinders. So I don't think the analogy works quite the same. If we had a radiator the size of the Atlantic Ocean (literally) then it would be different. But for us it's more complex, as you know.
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To do so, you use more fuel. There is the 'red box' zone where you can cause damage using less fuel than more, but with modern fuel controls we could eliminate that.
 
Clark1961 said:
He can in a turbocharged aircraft - I do it on most every flight.
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I don't care what you've got in the way of a piston engine. Part-throttle power output is a function of MP, RPM, inlet air temp, and pressure altitude. Mixture is not part of the equation. Read any aircraft engine text/manual and you'll see.
 
Ron Levy said:
I don't care what you've got in the way of a piston engine. Part-throttle power output is a function of MP, RPM, inlet air temp, and pressure altitude. Mixture is not part of the equation. Read any aircraft engine text/manual and you'll see.
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I think that's because most of those aircraft manuals don't show the LOP side of things.

When ROP, %hp will be related mainly to the amount of air available. When LOP, %hp will be related also to the amount of fuel available.

If you don't believe it, Ron, here's the extreme example: Go out and set up for cruise however you'd like - Then, pull the mixture to idle cut-off. Your MP, RPM, inlet air temp, and pressure altitude will be the same (for a short time, at least! Then you'll have to come down! ;)) but your %hp will obviously not be the same.
 
flyingcheesehead said:
If you don't believe it, Ron, here's the extreme example: Go out and set up for cruise however you'd like - Then, pull the mixture to idle cut-off. Your MP, RPM, inlet air temp, and pressure altitude will be the same (for a short time, at least! Then you'll have to come down! ;)) but your %hp will obviously not be the same.
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That transient case proves nothing.
 
Ron Levy said:
Their IM's are available on line for perusal.
http://www.cirruslink.com/mycirrus/onlinepoh.aspx

Problem with doing that in your Maule is that the %HP you get at any given MP/RPM combination varies with density altitude. The Cirrus takes care of that with a digital computer that automatically determines %HP based on MP, RPM, pressure altitude, and temperature.

But for your approach work, you can definitely come up with standard power settings for particular configurations (e.g., MP/RPM/pitch attitude to get 80 knots and 400 ft/min with one notch of flaps for ILS final). Read Chapter 3 of Peter Dogan's The Instrument Flight Training Manual, widely available in the internet, for more on that subject.

And if you really want a %HP display in your Maule, you can get that with most of the JPI EDM-series engine analyzers.
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Thanks for the link.

I'm currently flying an RV10 with a lot of bells and whistles. I display and record %power but don't really know how it's calculated though I know I had enter some information from my Lycoming manual.

Yes, in the Maule I didn't know or care much what was happening. WOT most of the time, lean to roughness above 6,000 then back it off for smoothness. 113 knots was the best TAS I would ever get.. until it fell to 110 after 1500 hours.

Calibration of all the instruments is the wild card in all these data collection efforts.
 
Ron Levy said:
That transient case proves nothing.
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OK, Let's try a less extreme example. Go out, set up for cruise, lean of peak, at 12.5 gph LOP. Now, further lean the mixture to 10 gph if you can, changing nothing else.

Do you still believe you're running at the same %hp?

The *only* thing that has changed is mixture, but the %hp will be vastly different.
 
I'd guess the Cirrus is just like any other engine monitor I have used (EI, JPI) and the %HP is a computation based only on MP and RPM.

I did get a checkout in a new SR22T but we didn't go over these specifics.
 
Does this help?

Redfin.jpg


LOP, power is directly linked to fuel flow, hence the straight line and an axis that can be labeled either in fuel flow or %hp.

IOW, LOP in an SR20, 10 gph will always be 75% power and there's a formula from which that can be derived: fuel flow times about 14.9 equals HP.
 
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Nice charts. Note that there is nothing there about MP/RPM. Pull back the mixture like that, and you will see a change in RPM (fixed pitch) or MP (c/s) as well as %HP.
 
Ron Levy said:
I don't care what you've got in the way of a piston engine. Part-throttle power output is a function of MP, RPM, inlet air temp, and pressure altitude. Mixture is not part of the equation. Read any aircraft engine text/manual and you'll see.
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Ron - I can fly 30", 2400 rpm at constant altitude and OAT and vary IAS from ~110 to ~116 by burning either 9 or 10 gph. Are you trying to tell me that engine power output isn't changing? And those are part-throttle operations and reading a book won't change the facts one wit.
 
Ron Levy said:
Nice charts. Note that there is nothing there about MP/RPM. Pull back the mixture like that, and you will see a change in RPM (fixed pitch) or MP (c/s) as well as %HP.
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Sigh.... Ron, engines have never been your fortè. I can have 22" & 2400 at 14gph 10° LOP, push the power lever forward to max, pull the mixture back to 14gph 30° (or whatever it works out to) LOP, I'll be making the same power and going the same speed.
 
dell30rb said:
Right on.

75% power is fine but you have to watch the CHT's
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Well, there's nothing wrong with running at 75% power. However I wouldn't expect to have as good of cylinder life, at least not on a big bore Continental. On a Lycoming, maybe a different story depending on the model.
 
Ted DuPuis said:
Henning hit the nail on the head.

The issue with Cirrus engines isn't the engine or the airplane, it's Cirrus marketing and their recommended operating practices, which people follow. LOP is good. 85% power cruise is bad. 85% is not a cruise setting.
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Where can you cruise low enough to cruise at 85% with a NA engine? I guess I'm just used to being out west where you have to be at least 8000 to go anywhere.
 
Ron Levy said:
Nice charts. Note that there is nothing there about MP/RPM. Pull back the mixture like that, and you will see a change in RPM (fixed pitch) or MP (c/s) as well as %HP.
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My MP gauge must've been inop. :confused:

I could run my IO-540 25x25 and lean until it nearly quit and the mp wouldn't change. I'm not sure why you think that the amount of fuel being burned would change the volume of air moving through an engine.
 
dans2992 said:
Where can you cruise low enough to cruise at 85% with a NA engine? I guess I'm just used to being out west where you have to be at least 8000 to go anywhere.
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In the eastern flatlands, it's possible. But you are correct that it's harder with a NA engine to run at or above 85%.

James_Dean said:
My MP gauge must've been inop. :confused:

I could run my IO-540 25x25 and lean until it nearly quit and the mp wouldn't change. I'm not sure why you think that the amount of fuel being burned would change the volume of air moving through an engine.
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Correct. Only on a turbo engine.
 
dans2992 said:
Where can you cruise low enough to cruise at 85% with a NA engine? I guess I'm just used to being out west where you have to be at least 8000 to go anywhere.
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Lots of places, NOT out west. ;) You can get 85% power up to about 4500 feet MSL on a standard day.
 
Ron,

Engines turn air and fuel, into kinetic energy through a chemical reaction called oxidation. You already know that, I know, but the amount of energy is related to the size of the reaction. You have two reactants, fuel and air. The throttle manipulates air, the carb/fuel injection system manipulates fuel.

%HP will be equal to the power made by completely utilizing the limiting reactant. If your throttle is wide open and you pull back on the mixture, fuel will become your limiting reactant at some point. If you leave the mixture alone and pull the throttle back, air will quickly become your limiting reactant.

The engine tables you refer to include all the variables which determine the available MASS of air. This is a result of them being formulated with the idea that air will always be your limiting reactant. Once fuel becomes your limiting reactant (LOP) the variables that determine mass of air are irrelevant because there is not enough to fuel utilize the full mass flow of air. In short, you have so much air left over it is irrelevant in calculating horsepower. Mass of fuel however is much easier to measure. GPH is really the wrong unit to use, but it's close enough for us. To be really correct you'd use mass, (or weight like jets, pounds per hour). Fuel expands and contracts much less depending on ambient temp and pressure than air because it is a liquid, therefore it's much easier to calculate a rough mass flow rate.

You probably know all of this already, but maybe someone will find it useful.
 
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Sorry to bump. I talk to so many Cirrus owners who don't make TBO. Don't just lean to the blue line and run up to 85% power in cruise if you want the engine to last. TA says that you can LOP climb where you keep the power lever full forward and lean to 17.6. If you want your engine to last don't do it.

Make sure you double check that your cylinders are peaking together. If not, get a new injector on that cylinder.

This is coming from a TA Sr22 owner who has made 1000TT and plans to go TBO and beyond!
 
Jaybird180 said:
A rather pessimistic SR-22 owner told me that the engine in the SR-22 tends to not make TBO. I don't have any data either way on this matter, but would like some. He says it needs cylinders early. I simply nodded and said, Uh huh, uh huh.

Reading on this forum would indicate that the IO-550 is generally a good engine that doesn't have any "issues" that causes fleet-wide failures to make TBO.

Was this guy pulling my leg, or is there some basis for his claims of the same engine doing poorly in a specific installation, Cirrus specifically?

We were talking about the normally aspirated airplane/engine combo.
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https://www.savvyaviation.com/wp-co.../EAA_2010-07_dont-fail-me-now-(exh-valve).pdf
There are a number of factors that can contribute to premature exhaust valve failure. During cylinder manufacture/overhaul/repair, if the guide isn’t properly machined (reamed) to hold the valve perfectly concentric with the seat, a hot spot can develop relatively quickly.

For example, there’s considerable evidence that TCM had some valve concentricity issues on cylinders it manufactured during the late 1990s and early 2000s resulting in an epidemic of burned exhaust valves at 500 to 700 hours. TCM changed its manufacturingprocedures, and these problems seem to have subsided
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lotsa folks are convinced it hasn't, or at least has continued to be problematic
 
I have an IO-550-G. Basically the same as the IO-550-N that the Cirri use, except limited to 2500 RPM (and 280 hp). The Ovation3 and the STC that it uses can take the same engine with a new prop and turn it into a 2700 RPM IO-550-N for 310 hp.

65% LOP is the place to be. Had one bad exhaust valve early on (first annual, likely from before I had it), and it's been flawless ever since. We're over TBO now.
 
good recent (2018) thread in beechtalk titled - Why so many top overhauls?

also (2014) - Two more worn valve guides on G36 IO 550

& - Life Cycle of Exhaust Valve Failure Part II
 
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I’m near 2000 hours and going strong...some of my colleagues have exceeded 3000 hours. Oil analysis, engine data analysis, borescopes, filter inspections, and (less so) compressions together will tell you when it’s time to overhaul. Since the 100 hours after overhaul are by far the most likely time for engine failure, I will not overhaul until necessary. I recently got some really low compression testing results. Turns out the shop didn’t properly warm the engine. A warm engine produced results all in the 70’s. Always take compression results with a grain of salt.

I fly 65% or under, Lean of Peak, around 11.5 - 12 gph at 160 kts or so TAS.
 
run those cylinders cool....below 370.... and they will last longer than 700 hrs.
 
Checkout_my_Six said:
run those cylinders cool....below 370.... and they will last longer than 700 hrs.
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Stipulated that cooler=better as far as CHT goes.

But plenty of Continentals operated conservatively and with cool CHT’s still have cylinder issues at relatively low time.

IOW, you can’t always blame the operator for cylinder issues early on.
 
FastEddieB said:
Stipulated that cooler=better as far as CHT goes.

But plenty of Continentals operated conservatively and with cool CHT’s still have cylinder issues at relatively low time.

IOW, you can’t always blame the operator for cylinder issues early on.
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I agree.

Nearly all the engines I’ve worked on that need cylinder/valve work have been low use engines. There has been no trend that I can see that would indicate that the engines which have been run hotter than the magic 380ish degree CHT need more cylinder work than the ones that haven’t.
 
2016 SR22T G5 here. Always run at 75% / LOP. CHTs are under 380 and TITs under 1600

In 800 Hobbs and 700 tach, I’ve replaced 3 cylinders
 
here I thought all that brilliants the APS/GAMI guys were teaching was for a good reason.....no? o_O
 
jsstevens said:
Having flown a Cirrus once for ~1/2 hour...

The newer ones only have the single lever control (i.e. mixture is controlled by the computer). How do you run it LOP with that setup? Lower power I get-pull the lever back.

John
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Huh? Doubtful you’ve flown one if you think there is only a power level. Look to the right of the throttle for the big red know. Mixture control. Red.
 
MetalCloud said:
2016 SR22T G5 here. Always run at 75% / LOP. CHTs are under 380 and TITs under 1600

In 800 Hobbs and 700 tach, I’ve replaced 3 cylinders
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Lemme guess......#6, #5, & #2? if so, your climb power isn't set right....or you need more fuel flow on climb out. You need a few extra GPH than what the book calls....32-33GPH for cooling at redline power setting.

My climb routine is to take-off at red line fuel flow for max power....once cleared obstacles go for more rich flow for climb cooling at max rpm and max manifold. I also have the GAMI cooling mod for cylinder #6 and kinda have the #2 mod.
 
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Mmcwhirter said:
Huh? Doubtful you’ve flown one if you think there is only a power level. Look to the right of the throttle for the big red know. Mixture control. Red.
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Already corrected further up. I have roughly 1/2 hour of Cirrus time on a demo flight a long time ago. What I misremembered was there is no prop control. You are correct that there is a mixture control.
 
TheGolfPilot said:
Ouch, what power setting do you climb at?
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Balls to the wall.

Checkout_my_Six said:
Lemme guess......#6, #5, & #2? if so, your climb power isn't set right....or you need more fuel flow on climb out. You need a few extra GPH than what the book calls....32-33GPH for cooling at redline power setting.

My climb routine is to take-off at red line fuel flow for max power....once cleared obstacles go for more rich flow for climb cooling at max rpm and max manifold. I also have the GAMI cooling mod for cylinder #6 and kinda have the #2 mod.
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I think 3,5 and 6. But I’ll have to check when I’m home.

I get 40gph flow on climbs and all my temps are pretty cool in the climbs (unless it’s a hot day, and I’ll adjust climb rate to allow more air flow).

I’ll look into GAMI mod
 
MetalCloud said:
Balls to the wall.



I think 3,5 and 6. But I’ll have to check when I’m home.

I get 40gph flow on climbs and all my temps are pretty cool in the climbs (unless it’s a hot day, and I’ll adjust climb rate to allow more air flow).

I’ll look into GAMI mod
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Pretty sure that would be a waste as the 550 already has a tuned induction system
 
I know they are completely different animals... but in the turbo Bonanzas, if you run at the max continuous power (balls to the wall), they go through cylinders like oil. Reduce manifold and rpm after takeoff and the cylinders will go to tbo.

On the other hand. Cylinders are relatively inexpensive, replace them when they need replacing and enjoy the power.
 
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