Power setting LOP

[Pinecone]

12 hours ago, Will.iam said:

I agree with this. The main problem is balanced fuel flow. As flying rich hides the imbalance much better than flying LOP. Ot allows the engine manufacturers to be sloppy on fuel flow balancing if you only run ROP. When i first got my 252 it would not run very far lop before getting rough running. After gami balanced my fuel flow it runs LOP well. 

OTOH, GAMI refuses to sell me GAMIjectors for my 252 as the fuel flows are too closely balanced. 

The factory tolerances are pretty wide.  But it used to be worse before GAMI.  But even then, there were some engines that ran LOP without issues.  I have a good bit of hours in my friends T-34 with IO-550.  The engine that GAMI originally developed their injectors for.  It would run LOP all day long.

[Pinecone]

9 hours ago, Shadrach said:

For the op of this thread it is not an issue as injected Lycoming 4 Cyl typically have excellent fuel/air distribution out of the box. The stock injectors in your TSIO360 MB1 likely flowed very evenly and precisely. The intake manifold is the problem and necessitates uneven injector flow to create even fuel air ratios. The “three holed flute” design of the intake allows fuel to migrate from one cylinder to the next, causing a progressively richer mixture. The reason most Lycomings run LOP well in stock configuration is because fuel cannot migrate from one intake tube to another like it does with the Continental.

TSIO-360-MB and -SB have a balanced length intake.  Not the 3 holes flute like the IO-550.

[Shadrach]

2 hours ago, Pinecone said:

TSIO-360-MB and -SB have a balanced length intake.  Not the 3 holes flute like the IO-550.

Looks like I got burned by the interwebs.   Before posting, I did an image search of the TSIO360-MB1 and this turned up. My mistake. 

 

[Shadrach]

11 hours ago, 0TreeLemur said:

According to the attached figure (from the Lycoming engine operator's manual, which assumes ROP ops), at 6000 ft and 24"/2400 rpm you are running at about 73% power.  Based on my experience, I think at 9.2 gph you are running richer than you need to, possibly near to or in the dreaded "red box".  Here's why I say that:

At TOC, I level out, reduce to 2400 rpm and mp to where I want, close the cowl flaps, and let it speed up.  Above 5000 ft, WOT, else 24" MP typ.  At or below about 7000 ft, I quickly pull the mixture back to a ff of about 7.5 gph, then richen to 8.3 gph.   That's a good place to start the LF function LOP.  Richen to peak, then lean it back to about -15F LOP on the richest cylinder.  It will typically be right at about 8.2-8.5 gph.  That minimizes time spent in the "red box".   Higher than 7,000 you can lean a bit more than 7.5 gph, and start LF from there.

How well this works depends on your GAMI spread.

CHTs in the high 200s/low 300s at an OAT of 40° are not “Redbox” numbers.  It’s prudent to pay attention to the actual feedback from the engine, rather than generalized, one size fits all, theoretical recommendations. 

Here’s a controversial statement based on decades of operating a normally aspirated IO360 - The “Redbox“ does not extend into the lean side of the mixture spectrum for a Lycoming IO360. Its borders, while fuzzy, are located solely on the rich side of peak EGT.

 

[A64Pilot]

I don’t really have an exact definition of red box or red fin or whatever, but I know detonation is not primarily a function of mixture, it’s more predicated on possible ignition sources like too hot a heat range plugs or carbon or maybe an exposed tang of a helicoil etc (yes I know these are pre-ignition but as the result is essentially the same does it matter)? In the cockpit you can’t tell the difference.

But also MP and just plain on how hot is the combustion chamber (cyl head temps)

So in other words it’s sort of like the fire triangle, you have to have all three for a fire. To get into detonation and engine damage you pretty much have to have all three.

A mixture that can support detonation, an ignition source and a high enough power setting to enable it, although power setting and heat are very closely related. Heat in itself can be considered an ignition source, pure detonation doesn’t require a hot “thing” but heat alone is enough, think Diesel engine where heat from compression along with very low octane fuel is enough.

So often detonation is caused by requiring high power to climb over those mountains or whatever that results in high cyl head temps that are aggravated by slow climb airspeeds like Vy for example and the coffin nail could be the pilot who doesn’t want to spend the couple of GPH that actually may be so rich that it slightly decreases power and has nothing but negative results, except that it keeps cyl head temps down. Lower RPM increases the likelyhood of detonation, remember how the 70’s cars would ping on a hill but if you pushed the pedal down causing a downshift the pinging would stop? 

If and this is an arguable point, but IF you keep cyl head temps below 400F on a Lycoming IO-360 it’s not likely you can get into detonation period, not in a normal world climbing to a cruise altitude or at a cruise altitude.

However the extra 2 GPH or so that pretty much guarantees you can’t get into detonation if you run that mixture for 10 min and fuel cost $5 a gl then it cost you $6.

$6 per trip is a cup of fancy coffee, pretty cheap insurance, I say 10 min because I don’t care how high or how long your climbing, after the first 10 min of climbing your power is down so much that it’s likely you can’t get detonation from mixture anyway

Plus the lower cyl head temp you get is less stress on the engine and less stress will result in longer at least cyl life, and most of the time people measure engine health by cyl health. I’ve almost never seen rod clearance measured when cylinders are removed to see how much bearing wear there is.

This is of course assuming no one mis fueled you with Jet or your not trying to run car gas or something

[AndreiC]

Back to my data point. I looked at a video I took and the numbers I stated were slightly wrong (and they somewhat confused me). The correct numbers were: MP 24.7, 2400 rpm, 5000ft, 29.94” altimeter setting, 9.4gph fuel burn,15-20 degrees LOP. 

What confused me was the fact that with these numbers, my power calculator says I should have been putting out over 75% power, which worried me, as it could have meant I was operating the engine outside its cruise parameters. But with the fuel burn, 9.4gph *14.9 = 140 hp, so 70% power. But then I realized this must be because I was sufficiently deep in the LOP regime for the actual power to go down. So I assume I was fine. (Please confirm.)

[Shadrach]

5 hours ago, A64Pilot said:

I don’t really have an exact definition of red box or red fin or whatever, but I know detonation is not primarily a function of mixture, it’s more predicated on possible ignition sources like too hot a heat range plugs or carbon or maybe an exposed tang of a helicoil etc (yes I know these are pre-ignition but as the result is essentially the same does it matter)? In the cockpit you can’t tell the difference.

But also MP and just plain on how hot is the combustion chamber (cyl head temps)

So in other words it’s sort of like the fire triangle, you have to have all three for a fire. To get into detonation and engine damage you pretty much have to have all three.

A mixture that can support detonation, an ignition source and a high enough power setting to enable it, although power setting and heat are very closely related.

So often detonation is caused by requiring high power to climb over those mountains or whatever that results in high cyl head temps that are aggravated by slow climb airspeeds like Vy for example and the coffin nail could be the pilot who doesn’t want to spend the couple of GPH that actually may be so rich that it slightly decreases power and has nothing but negative results, except that it keeps cyl head temps down. Lower RPM increases the likelyhood of detonation, remember how the 70’s cars would ping on a hill but if you pushed the pedal down causing a downshift the pinging would stop? 

If and this is an arguable point, but IF you keep cyl head temps below 400F on a Lycoming IO-360 it’s not likely you can get into detonation period, not in a normal world climbing to a cruise altitude or at a cruise altitude.

However the extra 2 GPH or so that pretty much guarantees you can’t get into detonation if you run that mixture for 10 min and fuel cost $5 a gl then it cost you $6.

$6 per trip is a cup of fancy coffee, pretty cheap insurance, I say 10 min because I don’t care how high or how long your climbing, after the first 10 min of climbing your power is down so much that it’s likely you can’t get detonation from mixture anyway

Plus the lower cyl head temp you get is less stress on the engine and less stress will result in longer at least cyl life, and most of the time people measure engine health by cyl health. I’ve almost never seen rod clearance measured when cylinders are removed to see how much bearing wear there is.

This is of course assuming no one mis field you with Jet or your not trying to run car gas or something

Detonation is a function of peak internal cylinder pressure. Mixture affects internal cylinder pressure but suggesting that it’s the primary driver muddies the water. Ignition timing, temperature and piston speed, are all contributing factors. 

Precisely defining the “red box” in its entirety is not really possible for practical reasons. One would have to set subjective metrics on each side of the box and the edges would vary based on conditions. It is however, easy to define the center of the red box. It is the fuel/air ratio for a given RPM that produces the most rapidly propagating flame front which in turn produces the highest PEAK internal cylinder pressure and thereby the highest CHT. Typically ~40ROP. Small changes in mixture from that point either richer or leaner make only small differences in flame front propagation and peak ICP. At some point beyond those small changes, propagation and peak pressure start to decrease significantly (relatively speaking). At some from peak ICP, going leaner generates a somewhat more rapid decrease than the corresponding point on the rich side. The Lycoming graph I posted earlier presents a clear, conceptual picture of the spectrum. The center of the red box (highest peak pressure) is depicted in the graph as the top of the CHT curve (hottest point). From an internal cylinder pressure standpoint, at any manifold pressure, peak EGT or leaner is more conservative than 100° ROP. By ~50° LOP, The engine is getting to a place that’s more conservative than 250° ROP.  
However, it’s difficult to make direct comparisons. CHT (all other things being equal ) is more a function of peak ICP than mean ICP. Power is a function of MEAN pressure produced during the power stroke. The slower nature of LOP flame front propagation can produce equal (or higher) mean pressures with lower peak pressure. Sort of the difference between a hammer blow at the top of the power stroke (ROP) and a constant push (LOP).

EDIT: Hat tip to @bluehighwayflyer for catching a ROP/LOP typo. Correction made.

[Shadrach]

1 hour ago, AndreiC said:

Back to my data point. I looked at a video I took and the numbers I stated were slightly wrong (and they somewhat confused me). The correct numbers were: MP 24.7, 2400 rpm, 5000ft, 29.94” altimeter setting, 9.4gph fuel burn,15-20 degrees LOP. 

What confused me was the fact that with these numbers, my power calculator says I should have been putting out over 75% power, which worried me, as it could have meant I was operating the engine outside its cruise parameters. But with the fuel burn, 9.4gph *14.9 = 140 hp, so 70% power. But then I realized this must be because I was sufficiently deep in the LOP regime for the actual power to go down. So I assume I was fine. (Please confirm.)

See my post above. If the numbers you posted are accurate, your engine was in a very happy and conservative place. Running closer to peak and pushing all of your CHT‘s into the low 300s would be equally efficient from a BSFC standpoint and slightly faster with no detriment to cylinder longevity.

[A64Pilot]

LOP power calculations are pretty easy, because power is purely a function of fuel if your LOP knowing an engines efficiency to calculate the power produced you just multiply fuel burn by let’s just call it the efficiency number, for our angle valve 360’s I believe that number is 15, so 9.4 GPH x 15 = 141 HP which is less than 75% so you were safe.

As 75% power is 150 HP it stands to reason if your LOP any fuel burn up to 10 GPH is safe, above can be but you can make a mistake and cause damage, below 10 GPH and at least in theory you can’t. Still always watch CHT, open the cowl flaps if needed.

That number isn’t hard set in stone as of course higher RPM has greater frictional losses and there is only one LOP setting that achieves the greatest BSFC etc, but if I’m correct and our number is 15 it’s close enough, you can get deep into the weeds for sake of argument, but your splitting hairs

LOP power is a function of fuel flow because if your LOP that by definition means there is excess air available for combustion so fuel flow is the limiting factor.

Oh and I may be misremembering the number as I cruise well below that as I’m seeking efficiency and willing to sacrifice some speed for it, so I’m. ever near the limits.

It’s really tough to make a case for anything but LOP cruise assuming you’re cruising at low power anyway. Only time ROP is really called for is down low where high power is possible or if your in a hurry and time is more important than efficiency, or maybe at very high altitude where LOP just can’t make enough power, you have to go to best power to get up there.

At least in a NA engine people want to argue that you can go just as fast LOP as you can ROP but it’s not true, highest power is only at one mixture and that’s best power mixture, any mixture other than it is less power.

[Shadrach]

22 hours ago, A64Pilot said:

LOP power calculations are pretty easy, because power is purely a function of fuel if your LOP knowing an engines efficiency to calculate the power produced you just multiply fuel burn by let’s just call it the efficiency number, for our angle valve 360’s I believe that number is 15, so 9.4 GPH x 15 = 141 HP which is less than 75% so you were safe.

As 75% power is 150 HP it stands to reason if your LOP any fuel burn up to 10 GPH is safe, above can be but you can make a mistake and cause damage, below 10 GPH and at least in theory you can’t. Still always watch CHT, open the cowl flaps if needed.

That number isn’t hard set in stone as of course higher RPM has greater frictional losses and there is only one LOP setting that achieves the greatest BSFC etc, but if I’m correct and our number is 15 it’s close enough, you can get deep into the weeds for sake of argument.

LOP power is a function of fuel flow because if your LOP that by definition means there is excess air available for combustion so fuel flow is the limiting factor.

Oh and I may be misremembering the number as I cruise well below that as I’m seeking efficiency and willing to sacrifice some speed for it, so I’m. ever near the limits.

I’ve seen 15.XX used but we’re in “angels dancing on the head of a pin” territory. Friction losses are a consideration but one must also consider that the transfer of force (mechanical advantage) to the crank varies throughout the power stroke, and that those variations of pressure during the power stroke will differ with changes in RPM. 15 is a good round number that’s close enough.  Operating above 75% LOP (FF above 10gph) is not dangerous. If one has an engine monitor, it’s very easy to demonstrate why, but you must be at low altitude on a cool, high pressure day . You simply set book manifold pressure and rpm for 75% power at 100 ROP, and wait to observe steady state CHT‘s. Then reset the mixture on the lean side at wide open throttle. What will be observed is that 75% on the lean side yields lower CHT’s. And indeed more than 75% also yields lower CHT’s all other things being equal. This is a repeatable observation. At 1500msl on a cold day I can fly as fast or faster on less fuel with lower CHTs on the lean side.

It’s coming up on the time of year here in the mid Atlantic where flying at 4500MSL might equate to a DA of 1100 feet.  Under those circumstances it makes good practical sense to set mixture for the highest power possible on the lean side. Especially if you’re traveling westbound and will have to deal with high winds at higher altitude. This gives the operator the ability to fly low while enjoying a fuel burn that mirrors high altitude ROP operations coupled with a high TAS that yields optimal GS by staying below the strongest winds. Unfortunately, mixture setting can’t improve the ride down low when it’s bumpy.

[PT20J]

Since these LOP power from fuel flow multipliers get bandied about, it might be good to review where they originated and what assumptions went into them.

From Advanced Pilot Seminars:

"If you know that you're LOP, simply multiply the fuel flow in GPH times a factor that depends on the compression ratio (CR) of your engine.

14.9 for 8.5:1 CR (most normally aspirated and turbonormalized engines)

13.7 for 7.5:1 (most factory turbo-charged engines)

Both can be rounded up to the whole number without serious error, and slightly different CRs can be interpolated.

These factors are derived mathematically, as follows:

Normally aspirated and turbonormalized engines (Usually about 8.5:1 compression) have a BSFC of about 0.39 lbs of fuel per HP, ranging from between 0.385 to 0.40. Factory turbocharged engines are less efficient, with a BSFC of about 0.42 to 0.43. The actual weight of 100LL is about 5.85 pounds per gallon. Scientists and engineers prefer to use the mass of fuel for these calculations, but using a standard conversion to gallons works well enough for our purposes.

5.85/0.39 = 15.0 GPH per HP

5.85/.0425 = 13.7 GPH per HP"

Comments:

1. The calculation is numerically correct but dimensionally in error. What they meant to say is that it's 15.0 or 13.7 hours/gal per HP.

2. The difference between the initially stated 14.9 multiplier and the calculated 15.0 is unexplained.

3. The calculation assumes a BSFC which may or may not be exact for a particular engine. Additionally, BSFC is not a constant by varies slightly with mixture strength between peak EGT and the mixture for minimum BSFC.

4.  The density of 100LL used in the calculation is 5.85 lbm/gal. References I checked cite 6.01 - 6.02 at standard temperature and pressure.

So, there is a lot of uncertainty in the calculation. It's close enough to be useful, but it's not worth nit picking over a couple of tenths in the multiplier one way or another.

Skip

 

[Shadrach]

49 minutes ago, PT20J said:

Since these LOP power from fuel flow multipliers get bandied about, it might be good to review where they originated and what assumptions went into them.

From Advanced Pilot Seminars:

"If you know that you're LOP, simply multiply the fuel flow in GPH times a factor that depends on the compression ratio (CR) of your engine.

14.9 for 8.5:1 CR (most normally aspirated and turbonormalized engines)

13.7 for 7.5:1 (most factory turbo-charged engines)

Both can be rounded up to the whole number without serious error, and slightly different CRs can be interpolated.

These factors are derived mathematically, as follows:

Normally aspirated and turbonormalized engines (Usually about 8.5:1 compression) have a BSFC of about 0.39 lbs of fuel per HP, ranging from between 0.385 to 0.40. Factory turbocharged engines are less efficient, with a BSFC of about 0.42 to 0.43. The actual weight of 100LL is about 5.85 pounds per gallon. Scientists and engineers prefer to use the mass of fuel for these calculations, but using a standard conversion to gallons works well enough for our purposes.

5.85/0.39 = 15.0 GPH per HP

5.85/.0425 = 13.7 GPH per HP"

Comments:

1. The calculation is numerically correct but dimensionally in error. What they meant to say is that it's 15.0 or 13.7 hours/gal per HP.

2. The difference between the initially stated 14.9 multiplier and the calculated 15.0 is unexplained.

3. The calculation assumes a BSFC which may or may not be exact for a particular engine. Additionally, BSFC is not a constant by varies slightly with mixture strength between peak EGT and the mixture for minimum BSFC.

4.  The density of 100LL used in the calculation is 5.85 lbm/gal. References I checked cite 6.01 - 6.02 at standard temperature and pressure.

So, there is a lot of uncertainty in the calculation. It's close enough to be useful, but it's not worth nit picking over a couple of tenths in the multiplier one way or another.

Skip

 

The original calculations were APS numbers. Then someone created a CSV file that extrapolated multipliers for all compression ratios with an HP calculator (available here in the downloads section).  

Mathematically trying to differentiate between the the 14.89 used for 8.5:1 CR and the 15.13 used for our 8.7:1 CR Lycomings is like measuring two cubes of jello with a micrometer.

[A64Pilot]

CHT closely follows power output, a reason CHT drops as you go LOP is due to the power drop.

Depending on how you label high power, high power isn’t possible LOP or of course we could takeoff and climb LOP. Be foolish to do so but full throttle LOP is possible, significant drop in power and there is risk, but you can do it.

Don’t, because you could get yourself in trouble trying, best BSFC is just a bit LOP, roughly -20F, which isn’t much, enrichen just a tad and then your running full throttle at peak, which I think most agree could get you into detonation, and that could be a $50,000 oops and or a forced landing.

Personally the biggest reason for me to run LOP is efficiency, and you get even more efficient by slowing down. I cruise LOP almost always, usually at 8 GPH, yes that’s quite a bit off of full throttle, but I burn even less fuel than a Piper Cub or my C-140 as a function of fuel mileage, and it’s not just a little bit, it’s a whole lot less. It’s surprising when you run the numbers. At 6 GPH I’m 50% faster than a Cub in a four place airplane burning about .5 GPH more, but that’s slow even for me.

I don’t have an analyzer in this aircraft, I have before but the way I fly I don’t need one, it’s s misconception that you have to have one to run LOP, you don’t, just be sure to stay below a power setting where you could cause damage, which is something that I think you should do anyway. Stay South of 10 GPH, for me well South and yiu can do anything you want to with the red knob and not hurt the engine.

I’ve become risk adverse in my Retirement, the cost benefit analysis of high power LOP just isn’t there for me.

[Fly Boomer]

On 12/27/2023 at 12:06 PM, wombat said:

Cylinder temps are "OK" (Let's say 390, and redline is 470 on a Continental TSIO-520-NB)

While 390 may be “okay”, 470 is absolutely not okay.

[0TreeLemur]

On 12/28/2023 at 10:43 AM, Shadrach said:

Here’s a controversial statement based on decades of operating a normally aspirated IO360 - The “Redbox“ does not extend into the lean side of the mixture spectrum for a Lycoming IO360. Its borders, while fuzzy, are located solely on the rich side of peak EGT.

 

This doesn't disagree with what Mike Busch thinks either.   From his presentation posted to Savvy's web site, slide 44, this is how he conceptualizes the red box, it extends from just slightly LOP to about 75F ROP.  Its existence is of course contingent upon running the engine at more than ~65% power.

 

 

[Shadrach]

2 hours ago, A64Pilot said:

CHT closely follows power output, a reason CHT drops as you go LOP is due to the power drop.

Depending on how you label high power, high power isn’t possible LOP or of course we could takeoff and climb LOP. Be foolish to do so but full throttle LOP is possible, significant drop in power and there is risk, but you can do it.

Don’t, because you could get yourself in trouble trying, best BSFC is just a bit LOP, roughly -20F, which isn’t much, enrichen just a tad and then your running full throttle at peak, which I think most agree could get you into detonation, and that could be a $50,000 oops and or a forced landing.

Personally the biggest reason for me to run LOP is efficiency, and you get even more efficient by slowing down. I cruise LOP almost always, usually at 8 GPH, yes that’s quite a bit off of full throttle, but I burn even less fuel than a Piper Cub or my C-140 as a function of fuel mileage, and it’s not just a little bit, it’s a whole lot less. It’s surprising when you run the numbers. At 6 GPH I’m 50% faster than a Cub in a four place airplane burning about .5 GPH more, but that’s slow even for me.

I don’t have an analyzer in this aircraft, I have before but the way I fly I don’t need one, it’s s misconception that you have to have one to run LOP, you don’t, just be sure to stay below a power setting where you could cause damage, which is something that I think you should do anyway. Stay South of 10 GPH, for me well South and yiu can do anything you want to with the red knob and not hurt the engine.

I’ve become risk adverse in my Retirement, the cost benefit analysis of high power LOP just isn’t there for me.

It’s clear to me that it matters no number of factory power graphs, annotations, accompanying explanations and references will be sufficient to change your misperceptions and that is fine by me.  No one has ever asked you to operate your plane outside of how you see fit. I just wish you would stop stating your opinions as facts (especially with no supporting data).

When someone posts a question about engine operations they are typically looking for something more in-depth  than,

“you don’t need some fancy engine monitor to run LOP. Just run at less than 60% like me. I’m risk averse and you should be to because your engine will self destruct if you run more aggressively than I do and anyway there is no such thing as high power LOP and if there is you’ll shoot your eye out trying and…” 

How many pilots do you think have harmed their engines in the last several years incorrectly operating LOP?

[jetdriven]

Ive ran engines LOP with a single point Westach analog EGT.  run it at 65% power and lean to lose 3 KIAS.

[A64Pilot]

11 hours ago, Shadrach said:

 

“you don’t need some fancy engine monitor to run LOP. Just run at less than 60% like me. I’m risk averse and you should be to because your engine will self destruct if you run more aggressively than I do and anyway there is no such thing as high power LOP and if there is you’ll shoot your eye out trying and…” 

How many pilots do you think have harmed their engines in the last several years incorrectly operating LOP?

You changed what I said tremendously adding what you think.

The gist of what I said was that it’s possible to hurt the engine if your attention is somewhere else at high power and the mixture drift towards rich, like say be overwhelmed getting IFR reroutes and be assigned a higher altitude

How many have harmed their engines from detonation, I’d say hundreds, maybe more in the last year, my Brother detonated the IO-520 to death in the C-210, and my neighbor detonated a cylinder not to death but enough to have to replace it on his new Helicopter IO-540.

That’s two that I’m personally close two. In fact that’s the only piston engine damage that were family or close friends.

However if my Brother had been lower power it wouldn’t have happened, but he was trying to keep up with me in a 1,000 HP crop duster.

The helicopter, well they can’t really fly at low power

The gist of what I said is that you can’t hurt one by running any mixture below 75% power in a Lycoming, so why take the risk of attempting LOP above that?

Why even try to cruise above that? For those that money isn’t an object sure cruise high power and replace the engine as necessary, but if money is no object, why try for high power LOP? When in fact if your LOP it’s not likely you can actually get high power, for high power you want 100 ROP.

Ref why cruise at lower power, see attached, you do so for greatly increased engine life, ANY engine if run very hard doesn’t last nearly as long as one that isn’t.

• For maximum service life, maintain the following recommended limits for continuous cruise operation:
• Engine power setting – 65% of rated or less.
• Cylinder head temperatures – 400˚ F. or below.
• Oil temperature – 165˚ F. – 220˚ F.

From here and other places, this is just the first Google hit on

https://www.lycoming.com/content/leaning-lycoming-engines#:~:text=For maximum service life%2C maintain,Oil temperature – 165˚ F.

The reason I post these things is for those that are new enough etc to be asking questions on a forum. I try to give them info that they won’t hurt their engines, then later if they decided they want to go further they can.

My Brother didn’t know what he was doing, the helicopter guy was following some internet experts advice, cost my Brother a new engine, the helicopter guy just a cylinder, he got lucky. Both had engine monitors, both first sense of trouble was an unusual noise, My Brother thought the gear were “thumping” the helicopter guy heard a rattle, thought he had a collapsed lifter, replaced that etc before finally borescoping it and finding damage

 

[Pinecone]

On 12/28/2023 at 11:16 AM, Shadrach said:

Looks like I got burned by the interwebs.   Before posting, I did an image search of the TSIO360-MB1 and this turned up. My mistake. 

 

The strange thing is, the pic I posted was from an ad for a 231.  But -LB and -GB show the 3 hole flute style.

I know the -MB and -SB have the one pictured is I have a 252.  And the only difference between those two are the RPM and MP red lines.

[Pinecone]

We had a detonation event in a CAP 182 with low compression O-470.

 

[Shadrach]

2 hours ago, Pinecone said:

We had a detonation event in a CAP 182 with low compression O-470.

 

Any idea what caused it? I’ve seen a number of detonation issues over the years. 0% of them were attributable to LOP operations. 

[A64Pilot]

I don’t disagree, if your let’s call it truly LOP you can’t detonate.

The issue as I see it is you have to maintain a pretty narrow EGT range, once you get say -50 or so LOP power falls off of a cliff, it’s safe just slow. 

Then there are engines that will run LOP but just barely, my newly overhauled with new Millenium cylinders IO-540-W1A5D with Gami injectors and new fine wires wouldn’t run any deeper than -10 or maybe -20 LOP before it got rough, so it’s margin was even smaller. It didn’t take a whole lot to put it into a mixture where detonation is possible.

That’s why I preach to run at a power setting that no matter what you can’t get into detonation. Maybe it’s just me, but I occasionally make mistakes, be flying for awhile and realize the boost pump is on, I’ve even found myself trimming out in cruise to discover the flaps were in takeoff position.

As I said all it could take is a slight climb without re-leaning to put yourself into a mixture that you could detonate, and I know if I fly long enough that’s one of those mistakes I’ll eventually make and I’m past the point of gaining experience, I’m at the point where every year in truth I’m not as good as I was the year before, for over 30 years I flew professionally, nearly every day I had Wx. Now I’m doing good to fly twice a week, but I’m determined to fly at least every week.

[A64Pilot]

2 hours ago, Pinecone said:

We had a detonation event in a CAP 182 with low compression O-470.

 

I think there is more mis-fueling possibly than we realize and or fuel contamination Apparently as the new fuel trucks require DEF, it seems people are putting DEF into the Prist tanks.

https://www.ainonline.com/aviation-news/business-aviation/2019-05-27/def-contamination-downs-two-citations

I remember taxiing an R-1340 Thrush over to the Albany Ga FBO telling the kid to top it off and as we are standing right in front of the big ole 9 cyl Radial he says these things take Jet, right?

At least he asked, I never thought I’d have to specify.

My private airplanes, I’m the only one that is allowed to refuel them.

Not saying that’s what happened there, who knows, maybe an intake leak, pre-ignition point whether carbon or piece of metal, maybe a damaged plug?

I assume it was not running car gas?

[A64Pilot]

The helicopter cylinder and piston, they tried to polish out the damage then wisely gave up. He wasn’t attempting LOP ops, I doubt any helicopter guy would attempt that.

He thought his fuel burn was excessive so they leaned the fuel servo out based on an internet expert. Luckily when it started making noise at a hover they started looking, they thought collapsed lifter, I thought maybe stuck valve, but it was detonation, of I guess you would call it “light” detonation.
 

[Shadrach]

48 minutes ago, A64Pilot said:

I don’t disagree, if your let’s call it truly LOP you can’t detonate.

The issue as I see it is you have to maintain a pretty narrow EGT range, once you get say -50 or so LOP power falls off of a cliff, it’s safe just slow. 

Then there are engines that will run LOP but just barely, my newly overhauled with new Millenium cylinders IO-540-W1A5D with Gami injectors and new fine wires wouldn’t run any deeper than -10 or maybe -20 LOP before it got rough, so it’s margin was even smaller. It didn’t take a whole lot to put it into a mixture where detonation is possible.

That’s why I preach to run at a power setting that no matter what you can’t get into detonation. Maybe it’s just me, but I occasionally make mistakes, be flying for awhile and realize the boost pump is on, I’ve even found myself trimming out in cruise to discover the flaps were in takeoff position.

As I said all it could take is a slight climb without re-leaning to put yourself into a mixture that you could detonate, and I know if I fly long enough that’s one of those mistakes I’ll eventually make and I’m past the point of gaining experience, I’m at the point where every year in truth I’m not as good as I was the year before, for over 30 years I flew professionally, nearly every day I had Wx. Now I’m doing good to fly twice a week, but I’m determined to fly at least every week.

You are full of opinions about operations that you’ve never conducted and data that you’ve never seen