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Can of Worms: O-360 CS Hartzell Setting Advice

Okay, so as the title suggests, I know I am opening a can of worms here. But single engine piston—and especially constant speed propeller stuff—is new to me, and if I’m being brutally honest with myself it’s a little bit mystifying.

I have flown jet aircraft for years, and between the Airbus I currently fly, and the U-2 which I flew in the Air Force, I feel pretty stoopid when I have to actually think about what my engine’s doing. Heck, in the U-2 (yes, they’re still flying), you push the throttle to “mil” on takeoff and usually leave it there until descent. Now I have not one, but TWO more levers to think about.

I bought my first plane, an RV-6 with the above eng/prop setup a few months ago. I understand the basics, and have flown my plane a lot using a formulaic approach to settings, but I need more info. I shoot for <= 380 CHT, and my usual flying is at 6500 or 7500ft in the SF Bay area. I find my MP at cruise and full throttle is 22-2300, and I set the prop at 2300. Then I lean until peak, keep going until slightly rough, then back in a couple turns. I end up with about a 1250 EGT. Seems like about 130-140 kts IAS is where she’s happy.

Am I in the right ballpark? I’m not worried about how fast I can go; I want to keep my engine happy and dependable for as long as possible. I looked for threads here, and surprisingly didn’t see much. Also googled the **** out of this, and found some great advice for fuel injected 540s. Again, not much for our setup.

Fire away.
 
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Keith:

Welcome to the world of small aircraft.

For what's it's worth (since I fly an -8) but have the O-360 with Hartzell C/S here are my typical settings:

MP: 24 inches (or full throttle at higher altitude)
RPM: 2350
Lean: Highest EGT - less than 1400 (usually about 1380); CHT - highest is usually less than 340 (I believe 400 is the max that Lycoming recommends); oil temp is usually just below 180 (carburetor engine, results vary with the seasons.)

Leaning the way you described is fine. It always worked for me before I had instruments to tell me things like EGT and CHT. I don't have a fuel computer - if I did I would probably lean it a bit more but the readings above will keep your engine in good condition. Mine has run like a top (knock on wood) for 750 hours.

Chris
 
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0 360

Avoid continuous operation between 2000.2250 r/m. The tachometer should have a yellow arc in that range, most probably do not.Try running the rpm at 2350 or 2400, it should be noticeably smoother at that r/m.
The EGT reading is irrevalent. What you are seeking is a reading below peak EGT. Lean to peak then richen 50-100 degrees.
If your CHT's are under 400, at 7500' or higher it is almost impossible to hurt a normally aspirated Lycoming with the mixture control. It may or may not be possible to run lean of peak with a carburetor.
 
Thanks! So at higher altitude, what is your MP? Is my ~2200 at 7500 ft about right?

22 inches is about right. On longer trips, I like to fly at 7500-8500 feet and full throttle because that's where the O-360 is most efficient. So you're at full throttle there. At those altitudes, my MP will read somewhere between 21 and 22 inches.

The IO-360 guys get a little more MP there but not much.

I'm jealous of your U2 flying. It must have been a thrill. You'll have to get used to a different vantage point now, and look out for more traffic.;)

Chris
 
I?m envious of your flying experience!
Your prop/power/mixture procedure works fine. A couple notes I can think of;
Depending on which prop model you have, Check with your prop?s mfgr to see if there are any limitations for operating at certain RPMs continuously, and engines with carbs don?t benefit much when leaned too much past peak.
 
Thanks! So at higher altitude, what is your MP? Is my ~2200 at 7500 ft about right?

Yes. At full throttle, you should see the actual atmospheric pressure outside the plane, minus any losses going thru the air filter and induction system, plus any gain due to ram air pressure. A rough rule of thumb is 30? at sea level, minus 1? per thousand feet altitude. So for you 30 - 7.5 = 22.5?, about right. I assume you meant 22?, not 2200.
 
Great. Ideally I take off at full throttle (of course) and just leave it there until descent, assuming a cruise alt over 5000ft. It?s those other two squirrelly knobs that are so mysterious.

So do you lean in the climb? How about the prop? Say you?re climbing to 7500ft... When do the blue and red thingys become active? In what order? I feel like I know what to do when I get to cruise altitude (mostly), but how about on the way to it? Is this a lot of questions? If I have to ask, don?t I already know?!
 
Yes. At full throttle, you should see the actual atmospheric pressure outside the plane, minus any losses going thru the air filter and induction system, plus any gain due to ram air pressure. A rough rule of thumb is 30” at sea level, minus 1” per thousand feet altitude. So for you 30 - 7.5 = 22.5”, about right. I assume you meant 22”, not 2200.

Yes. Thanks! Man, that helps a lot.

Oh, and yeah, 22” Hg. See why I need help?
 
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Keith,

Yes...lean in climb. You said you have about 1250 EGT on takeoff; lean during climb to that EGT.
 
At altitude (7500' +), if you're happy with the cruise speed/fuel burn, then that's great. A lot of guys never seem to go above 2400 in cruise. I rarely do these days, if I'm just up boring holes. But you're leaving a lot of performance on the table for cross country work. Try to find an operations manual for the engine. With normally aspirated engines, operating up in the 7500-8500 foot altitude range, you don't get to 75% power unless you've got wide open throttle and turning 2700 rpm. At that altitude, full throttle and 2700 rpm, you should be burning almost exactly 10 gallons an hour, unless you have electronic ignition. That *might* buy you 1/2 to 1 gph at 75% power. (Many claim bigger savings, but they are typically running much less than 75% power.)

edit: Here are Van's numbers for the -7, which are very close to a -6:
http://www.vansaircraft.com/public/rv7perf.htm
Those 8000' numbers are at full throttle, 2700 rpm.

Yes, it might last a bit longer at 60% than 75%, but it's designed to run at 75%+ all day long & go 2000 hours. The ones that don't make TBO usually fall short because they weren't flown regularly; not because of running at 75%. There is somewhat of an exponential curve in fuel burn as you get past 60%, though... :)

Manifold pressure with a carb'd engine will be just slightly under atmospheric, at full throttle. Standard pressure chart:
https://www.avs.org/AVS/files/c7/c7edaedb-95b2-438f-adfb-36de54f87b9e.pdf

The most efficient way to operate, once you're at a reasonable cruise altitude, is at wide open throttle with the prop dialed back to limit RPM, if you're lower than ~8000'. This is a gross oversimplification, so get the operating manual & a book on piston engine operation. As others mentioned, there are 'yellow arcs' in rpm where you can't linger with metal props, and a couple of other cautions.

Charlie
 
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Not sure what model Hartzell you have.

This link may be of interest to you if you have this prop commonly used on RV's: https://www.vansaircraft.com/pdf/Hartzell_c2yr.pdf


New Hartzell "Blended Airfoil" HC-C2YR-1BF/F7496 Prop RecommendedFor Lycoming 360's With Electronic Ignition / FADEC Systems

Propeller vibration characteristics and stress amplitudes on a reciprocating engine installation are primarily mechanically generated by the engine. Any modification to the standard engine configuration to include high compression pistons, electronic ignition, FADEC, tuned induction and exhaust, and turbocharging or turbonormalizing have the potential to adversely effect the propeller vibration characteristics and stress amplitudes. Hartzell Propeller, therefore, does not endorse any such engine modification unless the specific engine and propeller configurations have been tested and found to be vibrationally acceptable according to FAR 23.907.

Such flight testing of a new “blended airfoil” propeller has been accomplished in accordance to FAR 23.907 to ensure compatibility with Lycoming O-360 engines and various ignition systems. As a result of this testing, Hartzell’s new blended airfoil propeller, model HC-C2YR-1BF/F7496 is approved for use as described below and is the recommended propeller for use on Lycoming O360 engines equipped with electronic ignition systems and FADEC. This propeller essentially eliminates the “no continuous operation” zone of the original HC-C2YK-1BF/F7666A -2 , -4 propeller, when operated in conjunction with the Lycoming O-360-A1A (undamped 180hp) engine. The specific approvals are indicated below:


Hartzell Propeller Model HC-C2YR-1BF/F7496 is vibrationally approved when mounted on Lycoming model O-360-A1A rated at 180 HP at 2700 RPM and equipped with magneto ignition and/or Lightspeed Plasma II or Unison LASAR electronic ignition installed in Van’s Model RV-8 and similar single engine tractor aircraft with the following operating restrictions:

1. Do not operate above 22” manifold pressure below 2350 RPM.

2. Operation above 2600 RPM is limited to takeoff. As soon as practical after takeoff the RPM should be reduced to 2600 RPM or less.

3. The propeller diameter limits are 74” to 72”.

Hartzell Propeller Model HC-C2YR-1BF/F7496 is vibrationally approved when mounted on Lycoming model IOF-360-A1A rated at 180 HP at 2700 RPM and equipped with Aerosance FADEC engine control installed in Van’s Aircraft Model RV-8 and similar single engine tractor aircraft with the following operating restrictions.

1. Do not operate above 22” manifold pressure below 2350 RPM.

2. Maximum engine RPM must be limited to 2650 RPM.

3. The propeller diameter limits are 74” to 72”.

Note:

No testing has been done, at this time, on the IO-360-A1A, AIB6 (200 hp) or other derivatives of that engine.

The HC-C2YK-1BF/F7666A-2, -4 propeller will continue to be available for those aircraft where its use has been tested and is approved.
 
Keith-

Not that this matters at all, but I have more than 27 years on the U-2/ER-2 program both as a GI and Engineer, and the RV-8 I fly is owned by a former Deuce pilot. We probably know a lot of the same people. Gimme a shout via PM and I'll give you my contact info. I'm very familiar with the mission profile of the Lady and can talk to you in terms you are familiar with. Easier to talk through this on the phone than message boards.
 
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O360-A1A power settings

Power settings for 55%, 65% and 75% power at varying altitudes, versus RPM and MP. I don't remember where I originally got this, but found it this afternoon on a backup of a long gone computer. Also have easier to read tables in my RV6 (O360A1A, Hartzell CS) which I have been flying for 22 years. Could get them next time at the hangar and bring them home and scan and post if desired.

Power Setting Table.jpg
 
Here's a Lyc document.
https://www.lycoming.com/sites/default/files/O-HO-IO-HIO-AIO%20%26%20TIO-360%20Oper%20Manual%2060297-12.pdf
You might not find your exact model listed, but all the parallel valve 360s for fixed wing a/c will look pretty similar.

Try page 3-41, a HP/altitude nomograph for an IO-360 M1A. Raw 8k' 2700 rpm is 135 HP. There is also a set of MP correction lines, and the 22" line indicates close to 140 HP. I'd assume that this is a correction for slightly improved efficiency due to lower backpressure on pistons with higher altitude; note that the graph on the left shows a straight 135 HP at 22"/2700 rpm. Corrected HP at 8k'/2400 rpm appears to be 126 HP.
 
Great. Ideally I take off at full throttle (of course) and just leave it there until descent, assuming a cruise alt over 5000ft. It?s those other two squirrelly knobs that are so mysterious.

So do you lean in the climb? How about the prop? Say you?re climbing to 7500ft... When do the blue and red thingys become active? In what order? I feel like I know what to do when I get to cruise altitude (mostly), but how about on the way to it? Is this a lot of questions? If I have to ask, don?t I already know?!

It seems no one exactly answered your question about the prop control. After cycling in runup, my prop is full for taxi and takeoff. After takeoff, when I am at about 500' AGL, I reduce the prop to cruise (my field is at 7K'. If I'm taking off near sea level, I blow through 500' before the rush of the RV takeoff has passed, so I may be somewhat higher). I usually go with 2400 but 2200 also works (2350 is the restricted rpm on my prop). I stay at that rpm until I am on downwind and/or my speed is at pattern speed, when it goes back to full. There's not much reason to fiddle with the prop in normal flight operations.

By the way, I seldom bother with MP since we don't get full power anyway at my field elevation, not to mention variations in density altitude. I find my injected engine does about 10-11 gph at full throttle and I set my cruise throttle at about 7-8 gph to get an indicated 135 knots in level cruise at around 8500'. These are probably not the most efficient settings but they are comfortable for me.
 
Climb/Cruise Power settings.

TAKE OFF AT SEA LEVEL:
Mixture full forward = Rich.
Prop full forward = Low Pitch, High RPM.
Power = Full forward.

CLIMB FROM SEA LEVEL:
Mixture full forward = Rich.
Prop = pull back slowly to 2,500 RPM
Power = pull back slowly to achieve 25? of manifold pressure.

As you gain altitude increase power with throttle to maintain 25? of manifold pressure; as you gain altitude start leaning mixture while monitoring cylinder head temperatures, and oil temperature; (?leaning starts, generally above 5,000?)
As your altitude increases your manifold pressure will slowly drop & even at full power you won?t be able to maintain 25?. This is normal unless engine is turbocharged.

LEVEL CRUISE FLIGHT:
Bring prop back to 2,300?2,400 RPM.
Bring power back to 21-24? of Manifold Pressure.
Bring mixture back as you previously described.
Lower manifold pressures will result in less fuel burned & less cruise airspeed.
As you descend from cruise altitude don?t forget to ease the mixture forward.
***ALL THAT SAID:: I SUGGEST SOME DUAL INSTRUCTION FROM AN EXPERIENCED RV PILOT WHO IS FAMILIAR WITH YOUR TYPE AIRCRAFT & ENGINE***
 
I see some differences in operation from my own. Not saying it's the only way to do it but I typically fly the throttle as the OP is used to in the Deuce... WOT from takeoff to descent. I'll pull the prop back a little (2500) for cruise climb, then set RPM for cruise (2250 for the Rocket or 2350 for the -8); the mixture at target EGT for the climb, then as desired for cruise (peak for the Rocket or 30 LOP for the -8).
 
My plane had your carbureted engine with a fixed Sensenich prop when I bought it.

On take off,full throttle, I got 2300 RPM during climb.

I have since changed the engine over to fuel injection and a C/S prop. I now take off ,full throttle,2700RPM and after clearing obstacles reduce the RPM to 2500 or 2600 leaving the throttle full in. Remember with the fixed pitch I only got 2300 to 2350.... My highly instrumented engine has lower CHT's in climb if I DO NOT reduce MP with the RPM reduction.

I agree EGT's are not important in value but are used to determine PEAK. Your 1250 EGT may be different if your probes were placed closer to the exhaust port or further away. Comparing one cylinder to another may help trouble shoot a problem (cold cylinder,intake leak ect).

Your method of leaning is likely to be LOP (lean of peak): lean to roughness then richen until somewhat smooth. LOP gives a reduction in CHT over the same percentage of power ROP (rich of peak). I have operated LOP for many hundreds of hours, in Mooney's,Bonanzas and My RV7.
My speeds at 8500 are similar 132 to 140 KTS indicated on 7.4 GPH for a TAS of 155 to 165 KTS...
 
Power settings for 55%, 65% and 75% power at varying altitudes, versus RPM and MP. I don't remember where I originally got this, but found it this afternoon on a backup of a long gone computer. Also have easier to read tables in my RV6 (O360A1A, Hartzell CS) which I have been flying for 22 years. Could get them next time at the hangar and bring them home and scan and post if desired.

Power Setting Table.jpg

Where can I get these numbers for my O-540 ?

Mark
Rv-10
 
I shoot for <= 380 CHT, and my usual flying is at 6500 or 7500ft in the SF Bay area. I find my MP at cruise and full throttle is 22-2300, and I set the prop at 2300. Then I lean until peak, keep going until slightly rough, then back in a couple turns. I end up with about a 1250 EGT. Seems like about 130-140 kts IAS is where she?s happy.

Fire away.

Mountain, I just got an RV7A and am also switching from 10 years of fixed pitch prop. There's a fellow named Deakin that is real good explaining this. There's a youtube with a guy quoting his graphs that I saw last night, but can't find now.

In that video using Deakin theory, they have a "red box" described as Peak EGT to 100* ROP, as this is the area where the engine is under the most stress *IF* producing 75* power (only at sea level). They recommend 25* LOP or 100* ROP and to try avoiding operating in the "red box". The red box isn't necessarily bad, but can reduce engine life if you're in it all the time (as I imagine a lot of rentals probably are).

In my previous Tiger, leaning your method was EXACTLY the same as attempting to do all of the above, but I was usually at 15* LOP. A lot of carbed engines can't handle lean of peak as fuel flow varies per cylinder if not injected.
 
Wow. This might be the most helpful series of posts on any forum ever. I really appreciate all the help, and the thought that went into it. And nobody even called me stupid! Thanks.

I have a bit more reading to do, thanks to your posts. I?m also very fortunate to have a great RV community at my airport, especially a few guys who have versions of my airplane and a lot more experience with it. I promise I?m listening to them. What I hoped for was some technical info I could refer to, and MAN, did I get it.

Again, thanks. Fly safe out there.
 
I have an RV-6 with a carburated O-360 and Hartzell C/S. It's most efficient to run it at full throttle above ~8000 ft during cruide. manifold pressure should be 24" or less. Set cruise RPM ~2400. Try to maintain your Cylinder temps as low as possible, preferably below 350 deg.

Jacksel
 
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