Leaning the DA20 C1 IO240 engine

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1911Tex
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Leaning the DA20 C1 IO240 engine

Post by 1911Tex »

At altitude, what is your procedure for lean of peak without a sophisticated engine monitor? I need to add that I cruise at 65% power (2400 rpm).
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Re: Leaning the DA20 C1 IO240 engine

Post by RMarkSampson »

I have an JPI EDM-900 but quite frankly never use its Lean of Peak feature. To go lean of peak, I simply level off, adjust the throttle to be well above 2400 rpm and then "do the big pull" and pull the mixture back until the engine slows and the rpm is closer to 2400. For me, the mixture knob is in the vicinity of the "e" of the word mixture on the panel plate. Be sure you do this with the electric fuel pump OFF, otherwise you will get a nice surprise when you turn off the electric fuel pump after the big pull and watch the engine rpm suddenly go way down. Your pilot buddy in the right seat will start reaching for the Engine Out checklist before you admit to your mistake and re-richen the mixture.

Anyway, my fancy EDM-900 does provide great confirmation that my EGTs are around 1400 (mine peak in the high 1400's if you watch them during the big pull) and fuel flow is around 5.5 gallons. Then just tweak the throttle and mixture until you are happy with the engine rpm, gauges and its smoothness. Of course altitude matters where things ultimately end up - if you are up at 6-8K, then 65% power is really around 2600 rpm and you will scoot along at a faster clip than staying lean and low. It is worth the climb to me especially if the air is smooth up there, the wind is not in your face and you have some country to cross...

Definitely don't try to climb to a higher altitude running at lean of peak, CHTs will quickly rise to uncomfortable levels (450 is red line on my EDM but anything above 360 and I am taking immediate action to reduce CHT temps). I've never seen a 380 CHT reading on any cylinder which is the one benefit of having a good engine monitor.
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Re: Leaning the DA20 C1 IO240 engine

Post by 1911Tex »

Thanks Mark.....I really appreciate your answer.
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Re: Leaning the DA20 C1 IO240 engine

Post by thefoxx »

What prop do you have Mark - I assume NOT the MT?
I have an JPI EDM-900 but quite frankly never use its Lean of Peak feature. To go lean of peak, I simply level off, adjust the throttle to be well above 2400 rpm and then "do the big pull" and pull the mixture back until the engine slows and the rpm is closer to 2400. For me, the mixture knob is in the vicinity of the "e" of the word mixture on the panel plate. Be sure you do this with the electric fuel pump OFF, otherwise you will get a nice surprise when you turn off the electric fuel pump after the big pull and watch the engine rpm suddenly go way down. Your pilot buddy in the right seat will start reaching for the Engine Out checklist before you admit to your mistake and re-richen the mixture.
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Re: Leaning the DA20 C1 IO240 engine

Post by RMarkSampson »

I do have the MT prop
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Re: Leaning the DA20 C1 IO240 engine

Post by thefoxx »

Ok. Was just wondering because i have the MT prop as well and dont seem to be getting similar rpms as you.

What rpm can you expect full power on takeoff? Wonder if calibration of my tach is off?

Maybe im just being too easy on her and need to throttle up more in cruise!
RMarkSampson wrote:I do have the MT prop
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Re: Leaning the DA20 C1 IO240 engine

Post by 1911Tex »

I have the MT prop as well. Noticeably less climb rate than the Sensenich; however in cruise as you lower the nose, it picks up rpm quickly and at 2400, its bang on 120 knots (64%). Never could accomplish near that with the Sensenich. That is the difference between a cruise and climb prop. Next flight I am going to test Marks method of leaning.
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Re: Leaning the DA20 C1 IO240 engine

Post by RMarkSampson »

Arthur,
I pulled my data from my EDM to answer your RPM question. I just looked at a couple of flights from the log but data points are probably consistent with all my flights. Data points are every six seconds so here are my best guess at averages: Upon full throttle and take-off flaps, speed 20-60 knots, RPM 2150-2180. Upon takeoff and through the first 500 feet of altitude, 65 knot climb, RPM 2200. Flaps Ups climbing through the next 500 feet of altitude, speed 75 knots, RPM 2300.
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Re: Leaning the DA20 C1 IO240 engine

Post by thefoxx »

Hi Mark,
Thanks for taking the time to do that! It sounds like my performance is pretty similar to yours which makes me feel better!

I think for my cruise performance I'm just throttling back to the point where it feels I'm not over working the engine. You know how you just get that feeling based on sound? I usually really don't try to over work any equipment I own whether it's a vehicle or aircraft.

I went out today and just experimented with higher cruise throttle settings and obviously got much better airspeed!

Is it detrimental to run at a higher than comfortable RPM (2400 RPM?) Or is that a fairly happy place for this engine? It just seems that even though throttle lever is about at 75% physically but that 25% left only gets about another 100rpm or so in cruise!

Is % an expression of RPM or just plain engine power?

If my questions sound like amateur hour.. it's because it is!.... And because I'm still learning the nuances of my first bird!
RMarkSampson wrote:Arthur,
I pulled my data from my EDM to answer your RPM question. I just looked at a couple of flights from the log but data points are probably consistent with all my flights. Data points are every six seconds so here are my best guess at averages: Upon full throttle and take-off flaps, speed 20-60 knots, RPM 2150-2180. Upon takeoff and through the first 500 feet of altitude, 65 knot climb, RPM 2200. Flaps Ups climbing through the next 500 feet of altitude, speed 75 knots, RPM 2300.
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Re: Leaning the DA20 C1 IO240 engine

Post by Diamond13 »

You actually can run that engine all day long at max 2800 rpm, naturally burning more fuel. I have flown from London Ontario Canada to Vero Beach Florida, 2800 rpm or slightly below. Also to Calgary and back, same thing. If you are doing proper maintenance/oil changes etc, no harm done except to your wallet.
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