My IO-550 upgrade journey

Martin Pauly

Martin Pauly

Line Up and Wait
PoA Supporter
Joined
Dec 27, 2011
Messages
924
Location
Cedar Rapids, IA
Display Name
Display name:
Martin Pauly
I bought my A36 in 2012, with ca. 1,600 hours on an IO-520-BB with quite a bit of history. Eight years and 1,000 flight hours later, I decided to replace the engine with a factory reman IO-550-B, using the D'Shannon STC and baffle kit.

I had a McCauley 3-blad prop, OK but not in great shape. In the end I decided to replace that one as well with a new Hartzell Scimitar prop. It turned out the prop governor was in bad shape, so I got a new one as well. Alternator and instrument pressure pump were replaced with overhauled units as well. And of course one always finds a few unexpected things along the way... Most of the firewall-forward equipment is now new or newly overhauled.

It wasn't cheap - think around $80K for the above. The performance difference is very noticeable on take off and climb. I can't yet say anything about typical cruise performance, because I've only run it with very rich mixtures so far. I could get used to seeing the airspeed indicator at 170 KIAS. The fuel flow at 20+ GPH, not so much. ;)

Shane Vande Voort in Pella, IA (Classic Aviation) did the installation, and went on the first flight with me. Here is how that day went.

 
Last edited:
Groundpounder said:
Am I correct in reading that you got 2600 hours out of your IO-520?
Click to expand...
Yes, that is correct. And it was still running fine when I took it out, with no signs that it was near its end of life. The youngest two cylinders were 1,000 hours old, replaced by the previous owners just before I bought the plane.

- Martin
 
Martin Pauly said:
Yes, that is correct. And it was still running fine when I took it out, with no signs that it was near its end of life. The youngest two cylinders were 1,000 hours old, replaced by the previous owners just before I bought the plane.

- Martin
Click to expand...

Wow, that is impressive
 
Very cool. :thumbsup::thumbsup::thumbsup:
But it looks like you tried to save money. ;)
False economy! :eek:
Go ahead and write the check for the missing Tornado Alley turbo-normalized system. Then the firewall forward in your Bo will really be complete (and your bank account completely empty). :D
 
GRG55 said:
Very cool. :thumbsup::thumbsup::thumbsup:
But it looks like you tried to save money. ;)
False economy! :eek:
Go ahead and write the check for the missing Tornado Alley turbo-normalized system. Then the firewall forward in your Bo will really be complete (and your bank account completely empty). :D
Click to expand...

Depends, he has a pretty impressive useful load, not sure the extra weight would be worth it.
 
GRG55 said:
Go ahead and write the check for the missing Tornado Alley turbo-normalized system. Then the firewall forward in your Bo will really be complete (and your bank account completely empty). :D
Click to expand...
The TAT TN system is fantastic, no question. But that's another $50K or more. I just can't do it. If money was no object, then sure... (Actually, if money was no object, I'd have a PC-12.) Living in Iowa, the number of flights I make where the extra speed or extra altitude capability from the TN could make a difference is so small for me, I just would rather spend the next big check on an EFIS and autopilot than a turbo.

If I lived in or near the mountains, then yes, absolutely!

- Martin
 
You'll enjoy it. That's the combination we have. 70s vintage A36 with IO550.

I remember 'new engine day'. Its like christmas, except that it is followed by 'write check to the installer day' :-0


How many hours of shop labor to get the D'Shannon baffles to fit ?
 
Last edited:
Were you running LOP or ROP to get that 2,600 hours?
 
Martin,
that engine mount fretting....wow!

Just watching it now.... looks great so far, but I couldn't help myself, have to chime in about something that is screaming to me
Take this for what what it's worth...I'm not an A&P.....just a mechanical engineer who's first job out of college was as a Maintenance Engineer in a pulp and paper mill. My job was to always be on the look out for issues and work with/advise the millwrights and maintenance folks...so it's just an indelible habit I suppose....and this is like seeing food caught in somebody's teeth, I can't focus on anything else in the picture!

Around the 11:00-12:00 minute mark there's a red hose resting on top of the injector tubing clamp, with the ignition harness resting on top of it. It's probably no issue at all, but that just screams potential fretting corrosion to me. I would think there should be a clamp of some sort there.

ok...now maybe I can watch the rest of the video.....
 
Peeling the onion! I grew up in my Dads auto repair business of the fifties and sixties when there was lots of motor overhaulIng going on. Tearing apart An engine was always exploratory surgery. You never knew what you were going to find until you started tearing it apart. In the case of engine/propeller/governor decisions its sort of the same thing. Once you’re into the project, you want everything in top shape when you’re done, so you make those decisions as you peel the onion.

BTW Martin, I enjoy and benefit from your videos immensely.
 
JOhnH said:
Were you running LOP or ROP to get that 2,600 hours?
Click to expand...
Trying to understand the intent of this question. How does mixture setting effect a major overhaul number? Cylinders were replaced during that 2600 hours, which is what would be effected by mixture, in my mind.
 
Martin Pauly said:
Yes, that is correct. And it was still running fine when I took it out, with no signs that it was near its end of life. The youngest two cylinders were 1,000 hours old, replaced by the previous owners just before I bought the plane.

- Martin
Click to expand...

Martin,

Do you know how many cylinders were replaced over the life of the engine? Also, where did the engine and cylinders come from? Factory reman, brand new, some specialty cylinder shop?
 
Salty said:
Trying to understand the intent of this question. How does mixture setting effect a major overhaul number? Cylinders were replaced during that 2600 hours, which is what would be effected by mixture, in my mind.
Click to expand...
The intention of this question was to find out if he was running LOP or ROP and to add to my personal knowledge base, which is admittedly not very deep.

I'd like know the intention of your objection. Did you think I was trying to stir the LOP/ROP debate? THAT was not my intent.
 
JOhnH said:
The intention of this question was to find out if he was running LOP or ROP and to add to my personal knowledge base, which is admittedly not very deep.

I'd like know the intention of your objection. Did you think I was trying to stir the LOP/ROP debate? THAT was not my intent.
Click to expand...
I don’t understand what mixture has to do with major TBO. From your question you seemed to be making a correlation.
 
Salty said:
I don’t understand what mixture has to do with major TBO. From your question you seemed to be making a correlation.
Click to expand...

It's actually a great question Salty, there are those who swear that running ROP destroys cylinders and causes engines not to reach TBO. They say LOP is the way to go, some even go against manufacturer recommendations and run LOP at higher power settings than the manufacturer recommends.

I believe Martin believes running LOP is the way to go, but I won't speak for him.

I'm a renter so I run the engine the way the owners want, which is per the manufacturer recommendations.
 
PaulS said:
I believe Martin believes running LOP is the way to go, but I won't speak for him.
Click to expand...
I do, yes. The fuel savings when running LOP (i.e. more nautical miles per gallon) are undisputed. The lower CHTs are also a fact; most people will agree that's a good thing for cylinder longevity.

If you dig a little deeper, you'll find that the time of peak cylinder pressure (thetaPP), or - more generally speaking - the cylinder pressure as a function of crankshaft angle is different ROP vs LOP. LOP has lower peak pressure (at the same horsepower) spread out over a longer time, compared with ROP. Some will argue that this is helpful not just for cylinder life, but also for the bottom end. I have not heard anyone argue that it'll hurt anything.

Regards,
Martin
 
Salty said:
I don’t understand what mixture has to do with major TBO.
Click to expand...
Does that mean you don't understand it, or you don't believe it?
From your question you seemed to be making a correlation.[/QUOTE]
Read it again and show me where I was MAKING a correlation as opposed to asking a question.

There is a great debate among a lot of people that are much smarter than me re: ROP/LOP. I don't claim to know the honest answer, so I ask questions like that to help me develop an opinion.

So what is YOUR opinion re: LOP?
 
I'm not seeing how mixture setting effects anything but the cylinders. The cylinders didn't run 2600 hours. So I don't understand the context of the question.
 
Salty said:
Trying to understand the intent of this question. How does mixture setting effect a major overhaul number? Cylinders were replaced during that 2600 hours, which is what would be effected by mixture, in my mind.
Click to expand...

I think he said that only two cylinders had been replaced, but the question posed was a legitimate one. The poster curious about whether or not LOP was employed and how it may have effected engine life.

Most cylinder rebuilders can inspect and tell you whether or not lean of peak has been employed.
 
Salty said:
I'm not seeing how mixture setting effects anything but the cylinders. The cylinders didn't run 2600 hours. So I don't understand the context of the question.
Click to expand...
.

The difference is at the valves and seats, not piston/ring/cylinder wear.
 
Seriously though, it will be interesting to see how the rebuild/upgrade works out. It will be interesting to follow.
 
Martin Pauly said:
I do, yes. The fuel savings when running LOP (i.e. more nautical miles per gallon) are undisputed. The lower CHTs are also a fact; most people will agree that's a good thing for cylinder longevity.

If you dig a little deeper, you'll find that the time of peak cylinder pressure (thetaPP), or - more generally speaking - the cylinder pressure as a function of crankshaft angle is different ROP vs LOP. LOP has lower peak pressure (at the same horsepower) spread out over a longer time, compared with ROP. Some will argue that this is helpful not just for cylinder life, but also for the bottom end. I have not heard anyone argue that it'll hurt anything.

Regards,
Martin
Click to expand...

Just an interesting side note, does anyone know which famous aviator was a proponent of LOP?
 
GRG55 said:
Go ahead and write the check for the missing Tornado Alley turbo-normalized system. Then the firewall forward in your Bo will really be complete (and your bank account completely empty). :D
Click to expand...

There are times and places when turbochargers make sense on piston engines. But my opinion after spending roughly a couple thousand hours flying naturally aspirated piston twins around and another thousand or so flying turbocharged piston twins around (including pressurized) is that the benefits rarely outweigh the costs. Much more maintenance, many more failure modes, noticeably worse useful load, and a bit more speed plus higher fuel burn.

Yes, sometimes the value proposition is there. But it's rare.
 
Ted DuPuis said:
There are times and places when turbochargers make sense on piston engines. But my opinion after spending roughly a couple thousand hours flying naturally aspirated piston twins around and another thousand or so flying turbocharged piston twins around (including pressurized) is that the benefits rarely outweigh the costs. Much more maintenance, many more failure modes, noticeably worse useful load, and a bit more speed plus higher fuel burn.

Yes, sometimes the value proposition is there. But it's rare.
Click to expand...
so....your airplane now is more economical? lol. :D
 
Checkout_my_Six said:
so....your airplane now is more economical? lol. :D
Click to expand...

The MU-2 is, in fact, more economical than the 414. If I look at cost per hour of the 414 compared to the MU-2, the MU-2 wins handily by roughly $100/hr. Then you add in that my block times are 25% shorter than the 414 and the $ per mile is significantly improved. Fuel burn per hour is higher by around 60%, but that comes with the ~25% reduction in block times and a significant reduction in maintenance, even using a service center.

The MU-2 is also extremely reliable and just a great airplane that has very predictable maintenance costs and intervals. That's not just me talking, it's the consensus among owners. But even if we'd ended up with a Conquest 1 or a Cheyenne I/II I think the value proposition would be there vs. the 414.

If you make the more common comparison of a TN A36 compared to a naturally aspirated 550 A36 or a 310 vs. a 320 or T310R, though, I just don't think the benefits are there if your flying is mostly east of the Rockies. And before anyone says "But you can top weather" I'll point to the flying I did in the Aztec and 310, both naturally aspirated, and almost never flew trips under 600 nm.
 
MBDiagMan said:
Just an interesting side note, does anyone know which famous aviator was a proponent of LOP?
Click to expand...
Do you mean there was just one famous aviator that was a proponent of LOP?
Amelia Earhrt? Tom Cruise? Harrison Ford?
 
Hey Martin,

I haven't had a decent Eggs Benedict in almost a year...

We should do something about that soon...
 
Ted DuPuis said:
The MU-2 is, in fact, more economical than the 414. If I look at cost per hour of the 414 compared to the MU-2, the MU-2 wins handily by roughly $100/hr. Then you add in that my block times are 25% shorter than the 414 and the $ per mile is significantly improved. Fuel burn per hour is higher by around 60%, but that comes with the ~25% reduction in block times and a significant reduction in maintenance, even using a service center.

The MU-2 is also extremely reliable and just a great airplane that has very predictable maintenance costs and intervals. That's not just me talking, it's the consensus among owners. But even if we'd ended up with a Conquest 1 or a Cheyenne I/II I think the value proposition would be there vs. the 414.

If you make the more common comparison of a TN A36 compared to a naturally aspirated 550 A36 or a 310 vs. a 320 or T310R, though, I just don't think the benefits are there if your flying is mostly east of the Rockies. And before anyone says "But you can top weather" I'll point to the flying I did in the Aztec and 310, both naturally aspirated, and almost never flew trips under 600 nm.
Click to expand...
I love how the TAT folks like to sell the + $60K TN conversion.....one can burn a lot of 100LL for $60K. lol :D
 
Checkout_my_Six said:
I love how the TAT folks like to sell the + $60K TN conversion.....one can burn a lot of 100LL for $60K. lol :D
Click to expand...

To be honest I'm not sure why people spend that money. But that's just me. :)
 
As someone with a 550 that's over TBO, your price-tag doesn't fill me with joy; hopefully I can get a few more years out of her.

Charles Lindbergh was a LOP proponent: "...the P–38 was considered to have an operational range of just 400 miles, but Lindbergh taught the P–38 pilots how to stretch the range to 950 miles by operating them oversquare and leaning them brutally. Some pilots were reluctant to follow Lindy’s guidance at first, afraid that they’d damage the engines, but ultimately the guidance became standard operating procedure for the aircrews."
 
You must log in or register to reply here.
Back
Top