Leaning the DA20 C1 IO240 engine

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RMarkSampson
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Re: Leaning the DA20 C1 IO240 engine

Post by RMarkSampson »

Arthur,
I'm currently in information overload to answer your question with some facts vice opinion - the EDM-900 Engine Management System has a program that shows you lots of squiggly line graphs and data dumps into Excel. Neat stuff but it is going to take me some time (and desire) to digest it all. What it does show me is I'm a creature of habit. Most of my cross-country flights, I set the RPM to the high 2400s, almost to 2500 with engine at LOP. There is good data to support those settings. EGTs are in the low 1400's. I cruise along burning about 5.5 GPH at around 65-70% HP. The engine seems to me to be happiest here.

During the solar eclipse - I flew to pick up my daughter from college, then up to Triple Tree, SC to experience the eclipse - and then back home. So on the fifth flight of the day I did have some "get home'itis" and ran closer to 2600 rpm, and upon descent - let it run to 2700 rpm. I've uploaded my EMS data in a spreadsheet and screen-shot a picture of the graph. Fuel Flow was between 6.2-6.7 GPH. Looking at my EMS numbers I tend to agree with D.13, you will not get into trouble driving her at 2800 rpm - the IO-240B is designed to operate comfortably at a 70-75% HP setting. Here are my one "do" and three "don'ts" that matter most to me:

1. Do run at higher RPM's at higher altitudes. Altitude matters. If you look at the POH, performance chart - you will see that the engine operating at 2,800 RPM is only running at 68% power at 8K. In fact, those higher altitudes don't even quote performance numbers at lower RPM. Too low of a power setting at an altitude above 6K and your AOA will just increase until you drop out of the sky (figuratively speaking)...

2. Don't try and run LOP at max RPM. From my experience, I do not believe you can run LOP and maintain 2,800 RPM. Throttle position is set high but it is almost irrelevant, For LOP, RPM is more governed by the mixture setting. Peak EGTs are around the high 1400"s for me. When I go LOP, the RPM will naturally drop to vicinity of 2,500 RPM (altitude depending). If I increase the mixture to get more RPM, then I am really running at Peak EGT. Thus to run at that RPM you should be running ROP, and as D.13 says, pay the price. I don't have any data that shows me running ROP at 2,800 so I can't give you a fuel flow number, but the POH has it in the 8+ GPH range. Maybe at 12K you can do it but I have not tried that.

3. Don't go lean of peak and climb - your CHTs will quickly rise into uncomfortable numbers. It has nothing to do with RPM because our MT props will not spin that fast in a climb. I'm taking action and richening the mixture anytime I see a CHT 360+.

4. Watch that you don't cold shock the engine upon descent. It is OK to be running at higher RPM but if you instantly richen the mixture and pull it back to idle or low RPM to descend then the stress on the engine is far greater than worrying about a high RPM setting.

Finally, just remember, I'm an amateur too. All my experience has been in the last five years of owning my DA-20-C1, listening to my A&P and reading Mike Busch's articles. Good stuff but I should not be classified as an expert...
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1911Tex
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Re: Leaning the DA20 C1 IO240 engine

Post by 1911Tex »

MARK: I have the same experience with with my MT prop, same takeoff and climb rpm performance as you indicated. 2400rpm cruise consistent through most altitudes (safe 64%) lean of peak) gives me 120 knots. Generally between 5.5-6 gals. per hour, right by the book.
ROBERT: yes you can cruise safely at 2800 rpm; however per Continental, you must be at or below 65% for safe aggressive leaning. Just my thoughts.
The I0-240 is a terrific engine, taking the best of the great 0-200/360 engines.
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1911Tex
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Re: Leaning the DA20 C1 IO240 engine

Post by 1911Tex »

Error in above content...should be 0-200/320 engines....
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hogster50
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Re: Leaning the DA20 C1 IO240 engine

Post by hogster50 »

I was at Diamond fest some years ago. They told me the engine will run all day at high RPM. 2400 plus. I run mine at different RPM settings during cruise. It's just me, I figure it's good not running at same RPM, like a car. But it's just me..... I change my oil and filter 25hrs. I have a MT prop....
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