IO-540 Leaning...

Beachcomber

Beachcomber

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Beachcomber
just acquired an aircraft with the IO-540 and I have a question on leaning procedures. Is it enough...to simply lean or enriched the mixture when necessary to strive for 1380 EGT and 380 CHT? I’ve read so much on leaning, my head is spinning. Sure was easier back in the old Skyhawk!

So my question is can I just forget about the LOP/ROP and simply make my mixture adjustments so that I consistently maintain 1380/380 temps? Seems like it’s the right balance and won’t harm the engine. May not always be the best performing nor most efficient, but is it effective and safe to simply follow that thought process?
 
I fly an 0-540, 250 HP, fixed pitch, no temp information. I lean to engine roughness and then rich for peak RPM. Works fine.

I also fly an IO-360, 210 HP, constant speed, with GEM temp information. Yes, I lean to the rich side at 1385F, no issues.

Both engines went well beyond TBO with no issues.
 
What plane? I have an IO-540 in my Saratoga. I have a jpi 830. If you’re running a MP / RPM setting of 65% HP or less then “Peek” really isn’t an issue. In my experience. Leaning to rough and enriching just enough to eliminate the rough run will have you LOP, assuming cylinder injectors are pretty even.

I’d highly recommend a good engine monitor. The ability to fine tune the leaning process will pay for the monitor in fuel savings alone.
 
arkvet said:
What plane? I have an IO-540 in my Saratoga. I have a jpi 830. If you’re running a MP / RPM setting of 65% HP or less then “Peek” really isn’t an issue. In my experience. Leaning to rough and enriching just enough to eliminate the rough run will have you LOP, assuming cylinder injectors are pretty even.

I’d highly recommend a good engine monitor. The ability to fine tune the leaning process will pay for the monitor in fuel savings alone.
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I have a Saratoga as well with the JPI 700 monitor. Doing a panel upgrade soon, which will have better engine monitoring. I also have the GAMI injectors. Wish I had the 830...very nice.
 
I fly a Trinidad with an IO-540. I set power by the book settings and fly at 65% power. When I first bought it I leaned to peak and then ROP 50-75 degrees, at cruise that was always right around 13.5 g per hr, depending a little on altitude. Now I almost always just set mixture off fuel flow, setting it at 13.5, maybe a little 13.8 if flying low, 2500-3500. From what I've read it's hard to hurt the IO-540 at the 65% power setting, plus I don't see much speed improvement at higher settings. I am having an ei MVP50 installed so we'll see if that changes my setting any.
 
That’s a good point GB regarding 65%. I too set at 65%. That’s gives me about 150 knots TAS at 14.5gph. I could go to 70% and fly 152 knots at 16.5 gph. Not appealing to me.
 
just to add.....full power above NA 7,000 feet MSL is going to be a safe power setting to lean....cause you will be lower than 70%HP.
 
I will echo what others have said above, but will take a tip from GB. I run 65% power pretty much all the time in cruise in the Lance, but have been leaning to 100° ROP on the CGR-30P. Always seems to pop me up about 1.5 GPH higher than what I expect. 50°-75°would put me right about 13.8 GPH like the book says. I had heard people talk about not running around 50° ROP though.
 
My Commander 114 - has an IO-540. I just had a JPI 830 installed, so no experience with LOP - yet. In my experience, it's not any different than any other engine (normally aspirated) - I've been able to run by the book, leaning to roughness, then enriching and watching the temps - with solid performance and my oil analysis so far (4-ish years) have been good.

A good engine monitor is important if you try to work with LOP. Good luck with the panel upgrade - I just finished one

Dean
 
BGF_Yankee said:
I will echo what others have said above, but will take a tip from GB. I run 65% power pretty much all the time in cruise in the Lance, but have been leaning to 100° ROP on the CGR-30P. Always seems to pop me up about 1.5 GPH higher than what I expect. 50°-75°would put me right about 13.8 GPH like the book says. I had heard people talk about not running around 50° ROP though.
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Again, from what I have been told, it's hard to hurt the IO-540 if you stay at 65% power. BUT, I am not an expert, the last thing I want to do is give bad advise! IMO 100 ROP seems a little to conservative.
 
Appreciate the responses. Seems best to first set power settings ~65%, then begin to lean to roughness, enrich, and keep temps around 1380/380. Thanks all. It’s a new engine, so want this sucker to run a good life up to and behind TBO.
 
Checkout_my_Six said:
btw....the CHTs are much more important than the EGTs. Using the EGTs for "relative" comparison is good, but absolutes aren't as important.
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Agreed. My CHT's across the board will be 10-20 degrees cooler LOP than ROP. I used the LOP function on the JPI 830 early on until I determined specific fuel flows that obtained the temps I liked. Now I simply lean to fuel flow and verify I like my CHT's.
 
I run an IO540 in my RV10. I did all the things necessary to run LOP (engine monitoring, injector balancing, study) and am very happy with the results so far (1,000 hours). I recommend all of that highly.

Sounds like you have what you need to run LOP (or ROP) already You may want use your engine monitor to check that your GAMI injectors are doing their job as designed.

Regarding temps: CHTs you want as low as possible and no higher than that specified in the manual. As others have pointed out, EGTs are only meaningful relative to each cylinder’s peak. The actual temp is kind of meaningless.

Leaning to rough and backing off to smooth at 65% or less wont get you in trouble. Manipulating the mixture to maintain those temps may cause you to run the engine just where you don’t want to.... though at 65% you still won’t hurt anything.

It would be worth your while to study up on LOP. You have the equipment needed to do it at all power settings (but not during the climb). You just need to check things are setup properly then learn how to utilize what you have to the max.

Here’s how I run my IO540: WOT at sea level takeoff with no less than 24gph. Starting at 1,000’ or above I lean to maintain the same EGT in all cylinders (i.e. very ROP). At cruise altitude I maintain WOT and do the ‘big pull’ bringing the prop back to approximately the MP and the mixture to peak EGT - 10 degrees or less. Cruising at 7-8k that means roughly 2200rpms, 22”MP and 11gph. CHTS are between 290 and 340. The mixture may be reduced a bit more during descent and won’t go forward until final approach in anticipation of a go around.

YMMV but you already have what it takes to burn a couple of gallons less per hour safely.




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So I have an IO 540 in my Bo and was going nuts trying to figure out the leaning procedure. I have a JPI 700 and was trying to figure the LOP method using that. There are some guys over on Beechtalk who run APS seminars and I think have a pretty good take on LOP ops. They like the JPIs but feel that you should use a "feel method" ( my word) to lean. They advise taking the plane up to 8K with everything full forward. at that point your RPMs and MPs will drop you won't be in danger of blowing anything up. They advise to trim the plane up, get her settled for a few minutes and then do what they call "The big pull" close your eyes and pull the mixture out at a constant rate, not to slow or gently but don't yank it out. When you feel the plane slow down( you'll feel it in your seat) you have hit LOP.
 
I’ve got to go back to post 1. Maybe the OP has read a lot about leaning, but some real fundamentals have been missed. An EGT of 1380 means nothing by itself. You could be LOP, ROP, or right on peak. The absolute number doesn’t tell you anything. Understand this concept, read the scientifically based articles about the subject (John Deakin for example), learn how to use your instrumentation and you’ll be good to go. There’s nothing head spinning about LOP ops and many advantages to running that way. Your IO540 will appreciate it.
 
Any leaning without good engine monitor is a bad idea especially at high power settings and lower DAs. Now as someone said above 7-8000 and less than or = 65% power you can not hurt IO540 .
 
As the OP, I appreciate all the feedback, tips and suggestions. I do need to get more familiar with my JPI 700 and lean correctly and consistently. I’ve read the manuals, and watched the videos (crappy ones), and will continue to research. I know what I’m doing won’t cause harm, but clearly there’s the right way that I need to grasp. Thanks all.
 
Some good advice here but let me add my thoughts. I had to pull a cylinder at annual due to low compression and had to rehone the exhaust valve seat. The shop I sent it to hates LOP ops but when I pointed out how clean the exhaust port of the cylinder was, they couldn’t argue. The valve seat was due to TCM valve guide misalignment. I attended APS and have studied extensively (read John Deakin’s stuff on this subject) and an EXCELLENT YouTube video (approved by John Deakin) is LOP by Martin Pauly. Very clear explanation of how and why. 50 degrees ROP is the absolute worst place to run.
I have a JPI 830 and you will find that the % HP is not that accurate. APS teaches to use 14.9 x fuel flow divided by max HP = % Power (use 15 for a very close but easier in your head math).
 
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