Do you climb at full power on big piston engines

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woxof

Pre-takeoff checklist
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woxof
I have been doing that. But, according to an article I am reading, it is not a good idea.

"If your POH has a limitation on takeoff power (usually two to five minutes where present), then follow it."

"Any other suggestion in the POH to reduce power for the climb should be viewed with extreme suspicion. I am tempted to say it should be universally ignored as bad advice, but that may be too strong. In any event, the normally aspirated engines are almost always rated for continuous full-power operation. Use it. On all these engines (again, normally-aspirated), the first observable reduction in MP from the fully open position will also lean the mixture. That's something you don't want to do. It is counter-productive because it can actually increase the peak internal cylinder pressure, and it moves the peak pressure too close to top dead center. You will usually see the CHTs rise if you do that."

"More and more, we're finding that the text in the POHs and other recent publications is very poorly written from an engineering standpoint, and often directly contradicts the hard data from the same manual. The modern (since the late 1960's) POHs seem to be written by the marketing departments, and then proofed by non-flying lawyers for CYA, with little or no regard for the engineering data, and more concern for maximizing speed and range numbers than for the proper operation of the engine. In some cases, the difference can lead to premature engine failure. To that extent, it is a factor in safe flight — as well as economical flight. I'm less interested in CYA for the manufacturers, or marketing hype, and more concerned with protecting my own A, thank you very much.

You follow some POHs at your own peril. For example, the POH for the Chieftain suggests a climb fuel flow of 27 to 30 GPH, with a limit TIT of 1,500°F. We demonstrate that on the test stand (briefly), and the accelerated burn time of the not-rich-enough mixture will usually cause light detonation. Even if it doesn't on any given day, it always causes very high internal pressures and CHTs, even higher than a full power, full rich setting. Over time, that abuse can cause worse results than mere light detonation."

"If you take off full-bore with any of the big flat sixes, the full RPM from most of them will make a lot of prop noise. If this is a consideration, reducing RPM by 100 or 200 RPM will make a big difference in noise output, and will not harm your engine in any way, provided you have the fuel flow set to redline, or more. It's not "optimal" for the engine to reduce the RPM, but in my opinion, it's a decent trade-off."
 
I go full max sustained power in climb (many have time limitations), it'll all be in the POH, sometimes for takeoff in the skywagon I'll pull the prop back a finger width if I have plenty of runway ahead of me.

Mixture and cowl flaps for target CHTs
 
IO-470-F
Full power all the way up.

If I’m not leaning on the way up, I’m getting progressively richer just because the atmosphere is thinner (I’m not making 100% power as I go up; MP keeps dropping).

I think accurate temp data acquisition from today can be superior to guidance in the POH or other older sources, but only if today’s guidance is statistically proven correct (think of the ROP vs LOP arguments of recent past).
 
woxof said:
I have been doing that. But, according to an article I am reading, it is not a good idea.

"If your POH has a limitation on takeoff power (usually two to five minutes where present), then follow it."

"Any other suggestion in the POH to reduce power for the climb should be viewed with extreme suspicion. I am tempted to say it should be universally ignored as bad advice"
Click to expand...

So does your POH have a limitation on takeoff power or not?
 
455 Bravo Uniform said:
IO-470-F
Full power all the way up.

If I’m not leaning on the way up, I’m getting progressively richer just because the atmosphere is thinner (I’m not making 100% power as I go up; MP keeps dropping).

I think accurate temp data acquisition from today can be superior to guidance in the POH or other older sources, but only if today’s guidance is statistically proven correct (think of the ROP vs LOP arguments of recent past).
Click to expand...

You leave mixture full rich all the way to say 8k??
 
James331 said:
You leave mixture full rich all the way to say 8k??
Click to expand...

Nah, wide open throttle, I start pulling back the red knob at 5k (field elev 600).

Also, I have a FMS due to an STC and I follow the related checklist.
 
455 Bravo Uniform said:
Nah, wide open throttle, I start pulling back the red knob at 5k (field elev 600).

Also, I have a FMS due to an STC and I follow the related checklist.
Click to expand...

What are your CHTs during all of this?
 
My engine, 310 HP normally aspirated, makes enough power that I could reduce power soon after takeoff, to complete my climb. And at one time I thought such a power reduction was a good idea, to promote a longer lifetime for the powerplant. But an instructor convinced me that safety is more important than engine lifetime, and safety is promoted by getting to altitude quickly, since altitude is your friend. So now I climb at full throttle until I level off, which takes 6 min for a 6000’ climb.

The POH, fwiw, says only this:
“Normal climbs are performed flaps UP (0%) and full power at speeds 5 to 10 knots higher than best rate-of-climb speeds.”
 
I know of one io550 that did not agree with such an arrangement.
 
woxof said:
I have been doing that. But, according to an article I am reading, it is not a good idea.

"If your POH has a limitation on takeoff power (usually two to five minutes where present), then follow it."

"Any other suggestion in the POH to reduce power for the climb should be viewed with extreme suspicion. I am tempted to say it should be universally ignored as bad advice, but that may be too strong. In any event, the normally aspirated engines are almost always rated for continuous full-power operation. Use it. On all these engines (again, normally-aspirated), the first observable reduction in MP from the fully open position will also lean the mixture. That's something you don't want to do. It is counter-productive because it can actually increase the peak internal cylinder pressure, and it moves the peak pressure too close to top dead center. You will usually see the CHTs rise if you do that."

"More and more, we're finding that the text in the POHs and other recent publications is very poorly written from an engineering standpoint, and often directly contradicts the hard data from the same manual. The modern (since the late 1960's) POHs seem to be written by the marketing departments, and then proofed by non-flying lawyers for CYA, with little or no regard for the engineering data, and more concern for maximizing speed and range numbers than for the proper operation of the engine. In some cases, the difference can lead to premature engine failure. To that extent, it is a factor in safe flight — as well as economical flight. I'm less interested in CYA for the manufacturers, or marketing hype, and more concerned with protecting my own A, thank you very much.

You follow some POHs at your own peril. For example, the POH for the Chieftain suggests a climb fuel flow of 27 to 30 GPH, with a limit TIT of 1,500°F. We demonstrate that on the test stand (briefly), and the accelerated burn time of the not-rich-enough mixture will usually cause light detonation. Even if it doesn't on any given day, it always causes very high internal pressures and CHTs, even higher than a full power, full rich setting. Over time, that abuse can cause worse results than mere light detonation."

"If you take off full-bore with any of the big flat sixes, the full RPM from most of them will make a lot of prop noise. If this is a consideration, reducing RPM by 100 or 200 RPM will make a big difference in noise output, and will not harm your engine in any way, provided you have the fuel flow set to redline, or more. It's not "optimal" for the engine to reduce the RPM, but in my opinion, it's a decent trade-off."
Click to expand...
Please share with us the source of the article and the qualifications of the individual that wrote it. Thanks
 
455 Bravo Uniform said:
No digital CHT. CHT stays below what I see during ROP cruise (leaning with EGT, 150 ROP).

I’m at 5k in less than a few minutes.
Click to expand...

No kidding, I've always targeted max 350 cruise and 380 climb, whatever gets me there, but running fat on the climb robs you of power
 
James331 said:
No kidding, I've always targeted max 350 cruise and 380 climb, whatever gets me there, but running fat on the climb robs you of power
Click to expand...

Indeed it does. I’m at TPA right as I start my turn to crosswind when I’m doing pattern work though, so climb power is not a factor (the only time I wish I had more power is when I’m at cruise, for speed).
 
Ut oh, looks like someone found Pelican’s Perch...

I was told to limit WOT to 5 minutes max. I noted CHT at 405 during climb out the other day. I typically go to a cruise climb setting (top of the green arc on MP) once I get a cou0ke thousand ft up.
 
Full throttle provides cooling. I always leave throttle full in but the prop comes back to 2600 as soon as flaps are retracted after liftoff and/or obstacle clearance. Full power is too noisy, especially in cool or cold weather.
 
Stewartb said:
Full throttle provides cooling. I always leave throttle full in but the prop comes back to 2600 as soon as flaps are retracted after liftoff and/or obstacle clearance. Full power is too noisy, especially in cool or cold weather.
Click to expand...

Merica?

 
Depends on the engine.

In most flat (horizontally opposed) non-turbo engines, yes, I do climb at full power.

Turbo or supercharged: I respect the published limits.
 
Full rental power to altitude in my TSIO-520D (285 HP).....no power back till we level off. CHTs stay cool with the cowl flaps open and the fuel flow high. I do lower the nose once the gear is up. Then we build speed and do a full power cruise climb....something around 140 kts and +1,000 fpm. :D
 
With a IO540 (300 hp) I was instructed to use full power till about 1000 feet above field elevation, then pull back to 25 manifold pressure. The engine is rated full throttle for 5 minutes.

Sent from my SM-G950U using Tapatalk
 
drotto said:
With a IO540 (300 hp) I was instructed to use full power till about 1000 feet above field elevation, then pull back to 25 manifold pressure. The engine is rated full throttle for 5 minutes.
Click to expand...
This is what I always did. Reduce to "climb" power after reaching a safe altitude. C185s, C206s, C310s, etc. Wide open throttle all the way to cruise altitude was against the way I was trained and is just counter-intuitive. Reduced power always made it much easier to manage CHTs, across the different aircraft types.
 
edo2000 said:
This is what I always did. Reduce to "climb" power after reaching a safe altitude. C185s, C206s, C310s, etc. Wide open throttle all the way to cruise altitude was against the way I was trained and is just counter-intuitive. Reduced power always made it much easier to manage CHTs, across the different aircraft types.
Click to expand...

You were taught that way because the CFI that taught you learned it that way, from someone else who learned it that way, etc. Nobody in the chain bothered to stop and think about it, to understand how the fuel flow setups work, or to read any of the empirical data that supports that idea that full-power climbs (observing any temporal limits imposed by the manufacturer) are actually better for the engine. I think if you take some time to read some of the more modern, engineering-and-observation based stuff out there on engine operation, you'll find that most of the "experts" suggest wide-open throttle climbs at the max permitted RPM.
 
bradg33 said:
I think if you take some time to read some of the more modern, engineering-and-observation based stuff out there on engine operation, you'll find that most of the "experts" suggest wide-open throttle climbs at the max permitted RPM.
Click to expand...

I climb full throttle full prop, but that doesn't count in this thread as I'm flying a puny IO-360.
 
If we didn't need more power, they would have never made the 4360, gone to turbo-prop, or invented the after burner..the quest is never ending.
 
NoHeat said:
My engine, 310 HP normally aspirated, makes enough power that I could reduce power soon after takeoff, to complete my climb. And at one time I thought such a power reduction was a good idea, to promote a longer lifetime for the powerplant. But an instructor convinced me that safety is more important than engine lifetime, and safety is promoted by getting to altitude quickly, since altitude is your friend. So now I climb at full throttle until I level off, which takes 6 min for a 6000’ climb.

The POH, fwiw, says only this:
“Normal climbs are performed flaps UP (0%) and full power at speeds 5 to 10 knots higher than best rate-of-climb speeds.”
Click to expand...

I agree you want full power to safe altitude, but 2500 AGL is plenty unless you are over mountainas or highly populated areas.
 
PA46-350P...42" and 2500RPM full rich for takeoff in a TIO540...climb power is 35" and 2500RPM and leaned to 32-35 GPH, CHTs never go above 360.

There's no limitation or time restriction on full rated power but it just doesn't give me a warm and fuzzy feeling running this thing at 42" for half an hour.
 
How come my POH says max CHT is 460? Everything else I’ve been exposed to says don’t go over 400 and 380 is better.
 
JCranford said:
How come my POH says max CHT is 460? Everything else I’ve been exposed to says don’t go over 400 and 380 is better.
Click to expand...

Prob from Mike Bush....... My Redlines are blisteringly hot. I panic when I see 425 on climb out though. Cruise I hover right at 400 on my hotest with Gamis.
 
JCranford said:
How come my POH says max CHT is 460? Everything else I’ve been exposed to says don’t go over 400 and 380 is better.
Click to expand...

Continental or Lyc?

The ‘don’t let it get above 400F, try to keep it below 380’ has been floated specifically toward big bore Continentals for which a lot of experience has shown don’t handle heat as well regardless of what they originally published.

I did everything I could to keep my CHTs down in my Baron (IO-470s).

I don’t worry as much with my Pratt and Whitneys.

Engines in hell have Continental cylinders on Lycoming bottom ends.

Engines in heaven are all P&Ws.
 
I climbed my Cirrus SR22 with IO550 at full power and max rpm, except when I flew for AirShares - they wanted an rpm reduction to 2,500 rpm at 1,000’.

Thought: If CHT’s are trending higher than desired, why not just nose over and climb at a higher speed to improve cooling?
 
FastEddieB said:
Thought: If CHT’s are trending higher than desired, why not just nose over and climb at a higher speed to improve cooling?
Click to expand...
In my opinion, that's the best idea.

But sometimes you have to do both. In the Baron I climbed at FT and IIRC 2600 RPM (or whatever the POH recommended) and lowered the shallowed the climb as necessary for cooling. But, I remember times on hot summer days climbing out in the Baron where even lowering the nose wasn't enough to keep the temps down.
 
Fearless Tower said:
In my opinion, that's the best idea.

But sometimes you have to do both. In the Baron I climbed at FT and IIRC 2600 RPM (or whatever the POH recommended) and lowered the shallowed the climb as necessary for cooling. But, I remember times on hot summer days climbing out in the Baron where even lowering the nose wasn't enough to keep the temps down.
Click to expand...

To be fair to Conti, some of that is application specific, meaning that the way the particular aircraft application the engine is cowled under could be not doing it any favors. Not familiar with Contis beyond the cylinder woes, but IO-470s are generally regarded as the more resilient of the Conti NA offerings.
 
JCranford said:
How come my POH says max CHT is 460? Everything else I’ve been exposed to says don’t go over 400 and 380 is better.
Click to expand...

As @Ted DuPuis says, “Limits are not goals.” :)

For those with a way to measure, 400 is mo’ bettah than 460.

For those of us with a questionable single point probe and a manufacturer gauge, staying well below the top of the green is wise.

I’ll push my Cummins to limits on the ground. And did. And blew the head gasket. And got to pay to tow it and head work. (The cylinders and pistons all looked great they said! Didn’t hurt them at all!)

But I won’t push limits on the airplane. For all I know the baffles aren’t right on the other side from my single point probe and that side is pushing limits while this side is well below them.

But there’s reasonable empirical data that I’m probably not. (Most people who add a monitor don’t find one cylinder way high, they find valve problems by watching EGT. But that’s a different discussion.)

Those who can measure go off of the hottest one for their limits.

And by all means yes, give it more fuel, put the nose down and go faster, or reduce power or all three if you’re bouncing off the top peg on temperatures!
 
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