Kitplanes auto engine roundup...sad!

[Dan Thomas]

You also missed all the top ends/cylinders that need replaced at a few hundred hours. The cams/lifters spalled due to disuse etc etc.

And I have corrected you multiple times on this. First, most aircraft engines will run to TBO without cylinder problems or replacement. The larger engines, like 520s and 540s 550s, might need cylinder work sometime after mid-time. Most of those will be the turbocharged versions, since the engine is producing more power and more waste heat. More power is not free, you know.

Again, what is YOUR hands-on experience in maintaining all these engines you so constantly criticize? I was director of maintenance in a flight school and we never changed cylinders every few hundred hours. Not even on the 540s. Tell us, please, what your experience covers. The voice of inexperience means very, very little.

Cam and lifter wear is also largely a myth. The guys that suffer that are making very short flights, or ground-running the thing, pumping moisture into the crankcase via the blowby gases, which contain lots of water. There is no PCV system to clear it out, and only getting it up to operating temperature will drive it out. Lycoming went to roller lifters a long time ago already to try to mitigate the damage being done by owners.

Just try treating a car like that, and see how long it lasts.

So tell me again how a 1200-1500 non-required TBO number is meaningful when it will take the average person 20-30 YEARS to run it that long?

There are plenty of owners here that are flying hundreds of hours per year. You can't judge all POAers by your own limited experience.

 

[pfarber]

And I have corrected you multiple times on this. First, most aircraft engines will run to TBO without cylinder problems or replacement. The larger engines, like 520s and 540s 550s, might need cylinder work sometime after mid-time. Most of those will be the turbocharged versions, since the engine is producing more power and more waste heat. More power is not free, you know.

Again, what is YOUR hands-on experience in maintaining all these engines you so constantly criticize? I was director of maintenance in a flight school and we never changed cylinders every few hundred hours. Not even on the 540s. Tell us, please, what your experience covers. The voice of inexperience means very, very little.

Cam and lifter wear is also largely a myth. The guys that suffer that are making very short flights, or ground-running the thing, pumping moisture into the crankcase via the blowby gases, which contain lots of water. There is no PCV system to clear it out, and only getting it up to operating temperature will drive it out. Lycoming went to roller lifters a long time ago already to try to mitigate the damage being done by owners.

Just try treating a car like that, and see how long it lasts.

There are plenty of owners here that are flying hundreds of hours per year. You can't judge all POAers by your own limited experience.

Stats and numbers beat a random post on the internet.

Trying to pose as an authority because 'you know better' is a laughable attempt at self inflating one's ego. I'll never get into a 'issing match about how many log pages I signed because I lost count. How many IMU/EA packages have you replaced from a Trident C4 Backfit SLBM? How can you possible think you know more than me when I have done WAY more than you. See how dumb that is? Well, I'm sure you won't lol

Cam and lifter spalling is a MYTH? Wow, you just told us you are the uber expert on all things engines and say something like that? Camgaurd would like a work with you.. also thousands of lycoming motors is also on line 2.

Road tubes were a simple solution that simply lost out to more complex PCV setups.

As for 'average hours per year' that must have gone over your head. See, to have an AVERAGE you need numbers ABOVE and BELOW the calculated number to get, well, THE NUMBER. So yes, there are PPLs the fly more than the stated 25-50-ish hours per year... then are pilots that fly 0. THE AVERAGE is what it is... so let all sing along: The AVERAGE PPL is going to fly between 25--50 hours per year. We can do it as a roll if you like?

Thank's for playing. Lisa is backstage with your parting gift: the home version of 'I think I know more than you.. becuase I say i do!'

 

[StraightnLevel]

So tell me again how a 1200-1500 non-required TBO number is meaningful when it will take the average person 20-30 YEARS to run it that long?

It's meaningful because a large number of engines in legacy airframes are at or near TBO. Given the cost in both downtime and money, this becomes a serious barrier to movement at the lower end of the market.

Spam-can pilots who are plane-shopping intend to fly 100 hours or so per year, so an engine that is 200 from TBO is a real deal-buster for an entry level purchase. Meanwhile, the seller who lost his medical and has only flown 10 hours in the past three years isn't interested in dealing with a $70K engine rebuild for a plane that he paid $35K for in 2003; he just wants it sold so he can stop paying hangar rent and insurance.

 

[MauleSkinner]

Trying to pose as an authority because 'you know better' is a laughable attempt at self inflating one's ego.

So I really think you should stop doing it.

 

[tspear]

Ouch. The name calling is getting brutal.

Tim

 

[Bell206]

I snagged a run out IO-470. Working on lengthening the BD's fuselage for W&B (common mod),

So you start a thread to whine about the lack of auto engine options for aircraft, yet you select an IO-470 for your aircraft. Again, if this is such an issue why not develop an auto engine for your project?

 

[pfarber]

engines in legacy airframes are at or near TBO

I'm sorry to say this, and I really really want to be respectful to the large % of owners and MX out there (well, kinda sorta ):

IF YOU BELIEVE IN A TBO YOU ARE AN I D 10 T.

If you are not running your motor based off operational condition, then I don't want to hear how you don't have $60k to overhaul an otherwise fine running motor. This is very different than a life limited part, btw.

If your motor is 12 years since last overhaul... better rip it off the plane for no reason other that manufacturer liability. Which is the same 'liability' that seems to disappear when an AD requires a major inspection or part replacement.

 

[pfarber]

So you start a thread to whine about the lack of auto engine options for aircraft, yet you select an IO-470 for your aircraft. Again, if this is such an issue why not develop an auto engine for your project?

IT WAS CHEAP. I think I've posted more than once that my main concern is MONEY. If I can IRAN a IO-470 for cheap then I'll run it. I never, ever said converting a car motor was free/easy/fast.... but that it IS the answer to $60k overhauls. If its a boat anchor I can sell it for parts, and for what I paid for it I'd probably make my money back... I did say it was CHEAP, didn't I?

Of course the 'gotta try and prove to be smarter than everyone else' suspects don't see this... because, well, they ain't.

Lets see, my IO-470 can run a carb OR EFI. Getting rid of mags and expensive fuel controllers and pumps. I can run car spark plugs and put an effective pre-oiler / post oiler system and even run MOGAS and detergent oil. I can add a WAY MORE effective oil cooler and I can balance the intake runners and throw away that craptastically poor intake it came with. I can even add a bypass filter and a dry sump system to help control blowby and oil dilution. If you think that will cost a lot then ok, you're not into fabrication. I'd gladly spend a week welding an intake vs spending a few grand on overhauling aviation parts that work like crap.

None of that can be done on a certified engine. As long as the costs are reasonable I'll drag that 50 year old tractor motor into the 21st century whether it wants it or not.

 

[Bell206]

IT WAS CHEAP. I think I've posted more than once that my main concern is MONEY.

Then why start this thread? Maybe start a thread on how to get a cheap IO-470, weld it up in your backyard, and stick it on a BD-4?

 

[Dan Thomas]

I can run car spark plugs

And then fight radio noise in your headset.

and even run MOGAS and detergent oil.

Sure. Mogas is fine. But if you use automotive oil, the zinc it contains can kill your engine. From https://aviationoiloutlet.com/blog/can-automotive-oil-be-used-in-aircraft/ we get this:

The main difference in aircraft engine oil and automotive engine oil is the additives. The great divide between automotive and aviation oil occurred with the addition of zinc anti-wear and detergents containing metal: these metal containing additives did not bode well in the high-heat environment of an air-cooled piston engine. As mentioned above, these type of engines burn a large amount of oil, and any detergents containing metals and anti-wear compounds like zinc can form metallic ash deposits in the combustion chamber. This can cause pre- ignition within the chamber and actually burn holes in the tops of pistons...the results would be catastrophic to the engine. This is not something you want to happen while cruising along at an altitude of 15,000 feet. This is the main reason why aviation oils as we know them today remain ashless.

and I can balance the intake runners and throw away that craptastically poor intake it came with.

There is already a balance tube across the front of that system. You will have lots of fun trying to improve that system without ending up with something much worse, which is why I have never seen any STC'd aftermarket intake systems for these engines. Moreover, the 470's induction system is really light, and anything you change will add weight. And maybe you wonder why all the rubber-hose connectors in that system? It's because the engine expands and contracts a lot as it heats up or coos down, and the induction system has to be able to accommodate that. Cylinders move apart fore-and-aft, and across the engine. The exhaust system has slip joints to allow movement.

The induction balance tube:

I can even add a bypass filter and a dry sump system to help control blowby and oil dilution.

Please explain how bypass filter and a dry sump controls blowby and oil dilution. Both of those problems have nothing to do with the location of the oil tank nor a bypass filter. Blowby is blowby, and dry-sump air-cooled engines all suffer from it. Whatever gets past the rings and into the case is picked up by the oil, and if the full-flow filter can't stop it, the bypass filter won't either. Oil and water form an emulsion that passes through filters. Operating temperatures are the only thing that remove the water.

I'm sorry to say this, and I really really want to be respectful to the large % of owners and MX out there (well, kinda sorta ):

IF YOU BELIEVE IN A TBO YOU ARE AN I D 10 T.

Tell that to the guys that run their engines on-condition in operations like pipeline or powerline patrol, or fish-spotting. They take those engines to 3000 and 4000+ hours. In Canada we can do that in commercial operations like flight training, and some run those engines way past TBO, at the hands of clumsy students, too.
From AOPA:



A pilot on Reddit says this:


Another pilot said a friend had a Lycoming that was currently at 8000 hours since major overhaul. The guy had replaced several magnetos and two cylinders in those 8000 hours. TWO CYLINDERS IN 8000 HOURS, just so you don't miss that.

More testimonials:


And another:


From an A&P:


Again, 3500 hours on the original cylinders on a 540. Nobody is replacing cylinders every few hundred hours, as you claimed:

You also missed all the top ends/cylinders that need replaced at a few hundred hours. The cams/lifters spalled due to disuse etc etc.

I suppose you will take that IO-470 off your BD-4 every 500 hours for overhaul, right?

 

[Dana]

And then fight radio noise in your headset.

Has that been an issue for people running auto plugs? Lots of people running them, but I haven't heard that interference has been a problem.

 

[pfarber]

Then why start this thread? Maybe start a thread on how to get a cheap IO-470, weld it up in your backyard, and stick it on a BD-4?

Because not many people (95-99%) have the time/ability to take a core (or car motor) from zero to hero.

Also it was a Kitplanes engine roundup and they could simply cut and paste the article every year and just change the year.

Also also Kitplanes is a dead hollowed out shell of its former self and I must gaze down upon it with haughty derision at every opportunity.

Also also also maybe get some leads/tips/ideas for other car motor guys. there are dozens of us!

As for an article I will do that.... in Kitplanes format: start a interesting series on a popular topic, but then outsource everything and pretend I did it, then stop at installment 1 and never finish. Did I mention Kitplanes is a dead hollowed out shell of its former self?

 

[moparrob66]

I'd consider an air cooled legacy engine for my kit if I knew I could source affordable parts for it . How much do you think an experimental build or rebuild for an o-470 would cost compared to an A&P using FAA approved parts?

 

[pfarber]

And then fight radio noise in your headset.

You're not doing it right.

Car oil is a no go for air cooled engines... ok, got it. Thanks. I did find this:

• entastar V6: Rarely forms metallic additive deposits because the oil jets keep the piston underside around 450°F and the water jackets keep the head cool, preventing the oil from hitting its extreme thermal breakdown threshold.
• Continental IO-470 / AVDS-1790 Tank Engine: Highly prone to metallic ash deposits on the piston crowns and exhaust valve guides because these areas regularly run between 550°F and 650°F, acting like a frying pan that instantly vaporizes liquid oil and bakes the zinc, phosphorus, and calcium additives into a solid crust.

I know some 470s DO have oil squirters drilled into the con rod. most car motors do (even my 43 Ford 'Go Devil' did). Curios.

I really like how people accept lead deposit detonation as normal. One bad, two bad but 'eh, that's the way its always been'.

I'm not going to bother with posting the exact same number of 'my motor didn't make TBO' posts. Again lets all lift our eyes, hands and hearts to the great mathematicians of yore and open our spirit to the holy words of our father: an average mean 50% above, and 50% below.

Next you're gonna do a google search trying to prove you're more righter about how long a piece of string is. So tiresome.

 

[pfarber]

I'd consider an air cooled legacy engine for my kit if I knew I could source affordable parts for it . How much do you think an experimental build or rebuild for an o-470 would cost compared to an A&P using FAA approved parts?

The money saved will always depend on the core you start with (just like flipping any item, buy low sell high). I have a hard cost ceiling of $10k for parts. My labor is free, and I will use IRAN/serviceable limits. The core I bought was amazingly cheap so this is more of a gamble than most people might take... but if the crank is good I don't see an issue... depending on what else pops up.

If you spend the $60k for a shop than you should expect new limits. I am not spending that much and will be happy with an IRAN motor that runs and is thoroughly tested.

I have a car motor ready for conversion if estimated costs for the 470 get to high. A PSRU and EFI are available comfortably under my $10k limit.

 

[Dan Thomas]

I really like how people accept lead deposit detonation as normal. One bad, two bad but 'eh, that's the way its always been'.

Where do you get the idea that we accept detonation? Detonation kills engines real quick. Burns holes in pistons, overloads bearings, cracks heads. The POH or AFM gives the numbers for operating that engine, and those numbers are the result of test cell research. But there are plenty of owners/pilots who never consult the POH and they sometimes trash their own engines. We had a guy take off in his twin, and to show off with the takeoff and climb he overboosted it. Blew a head clean off the cylinder when the detonation started. Managed to get it around the pattern and land it.

Even opening the throttle too quickly can induce brief detonation. Do that often enough and you're eventually buying another engine.

Flying requires thought and knowledge. Without the knowledge you can't make intelligent decisions.

 

[moparrob66]

The Pentastar V6 is one I'm considering as well. Is there a psru that bolts up? I dont want to make my own unit or develop an adapter. Im also concerned about 3 miles of timing chain running around in there.

 

[pfarber]

Where do you get the idea that we accept detonation? Detonation kills engines real quick. Burns holes in pistons, overloads bearings, cracks heads. The POH or AFM gives the numbers for operating that engine, and those numbers are the result of test cell research. But there are plenty of owners/pilots who never consult the POH and they sometimes trash their own engines. We had a guy take off in his twin, and to show off with the takeoff and climb he overboosted it. Blew a head clean off the cylinder when the detonation started. Managed to get it around the pattern and land it.

Even opening the throttle too quickly can induce brief detonation. Do that often enough and you're eventually buying another engine.

Flying requires thought and knowledge. Without the knowledge you can't make intelligent decisions.

If you think your air cooled motor isn't detonating just about every time you fly they you don't have the wisdom to understand ICEs, you don't fly on hot days or do climb outs lol

Not every detonation event is catastrophic. And aviation engines do everything they can to prevent it, but it still happens... you just never know about it unless its the 'big one'.

Gemini sayith:

3. In Specific High-Performance Airframes: Continuously​

Advanced engine research (such as data analyzed by organizations like Savvy Aviation and GAMI) has revealed that a few specific high-performance, factory-built turbocharged aircraft engines actually operate in continuous light detonation on one or more cylinders during standard high-power cruise settings—even when operated exactly by the factory handbook. This is usually due to uneven fuel distribution in carbureted or standard fuel-injected systems causing one cylinder to run leaner and hotter than the others.

What Does "Light Detonation" Actually Mean for the Engine?​

Contrary to popular belief, light detonation is not an instantaneous death sentence for a low-output, large-displacement aircraft engine.

• The Frequency Scale: In certification testing, "incipient (light) detonation" is technically defined as 5 to 9 explosive flashes per minute within the cylinder.
• The Impact: Unlike heavy detonation (which can melt an aluminum piston or destroy a valve train in minutes), light detonation is relatively survivable. Industry testing has shown that robust, naturally aspirated aircraft engines (producing roughly $0.5\text{ hp/in}^3$) can withstand hours of light detonation with no immediate structural damage. In fact, occasional light detonation can actually scrub carbon and lead deposits off the piston crown.

​

[TR]
[td][/td]
[/TR]

Savvy says:
However, in real-world aviation, light detonation is more common than many pilots realize. Because it happens on a micro-second scale inside the cylinder and cannot be heard over the noise of the cockpit, it often goes entirely unnoticed.

At least car motors are smart enough to sense knock and retard timing. Air cooled motors either live with it or die from it.

 

[pfarber]

The Pentastar V6 is one I'm considering as well. Is there a psru that bolts up? I dont want to make my own unit or develop an adapter. Im also concerned about 3 miles of timing chain running around in there.

I'm not concerned with the chains as they are not wear items. The GUIDES may need attention, but swapping out guides every 500 hours is a once every X year event and cost is negligible. The ECM will also alert you to timing issues because it will monitor crank and cam positions.

There are a few 100-300hp PRSUs out there. My plan is to get simply get a plate and some isolation mounts and bolt right to the bellhousing. Most PRSUs come with or have available dampener mounts for the crank.

 

[Doc Holliday]

I'm not concerned with the chains as they are not wear items.

 

[moparrob66]

I'm not concerned with the chains as they are not wear items. The GUIDES may need attention, but swapping out guides every 500 hours is a once every X year event and cost is negligible. The ECM will also alert you to timing issues because it will monitor crank and cam positions.

There are a few 100-300hp PRSUs out there. My plan is to get simply get a plate and some isolation mounts and bolt right to the bellhousing. Most PRSUs come with or have available dampener mounts for the crank.

Would you use a Jeep manual ECM? Does it need a vehicle speed sensor input? Or are you planning on a custom ECM?

 

[pfarber]

lol someone it trying to be more smarter... to bad they can be easily proven wrong:

A timing chain is not considered a standard "wear and tear" maintenance item like brake pads or tires. It is an internal engine component designed to last the lifespan of the vehicle—typically between 80,000 to 120,000 miles, or up to 300,000 miles if properly maintained

Timing chains in modern engines are designed as 300,000-mile components under normal conditions. Some reach 500,000 miles before replacement becomes necessary. When you see severe wear at 52,000 miles, you’re looking at accelerated degradation caused by operating conditions or component failure, not normal service life.

Timing chains are different from timing belts in that they do not need to be changed for maintenance every few years, so there is not a recommended specific interval for getting it replaced

Unlike rubber timing belts—which are treated as routine wear items with mandatory replacement schedules (usually every 60,000 to 100,000 miles)—timing chains are explicitly engineered as "lifetime parts" designed to last the entire service life of the engine.

The original chains in my 245000 mile Caravan are quiet as a mouse. But I also use Torque and set the oil pressure PID to know exactly where my oil pressure is. If you're oil pressure light comes on, the damage is already done... that light is just a reminder to get out your ATM card.

Repeat after me: your guides and tensioners will fail LONG before a a chain. Tensioners will leak. A common fix for a noisy valvetrain on older F150s was a Melling high capacity oil pump. Way easier fix than replacing an entire timing/valve train.

PROVE. ME. WRONG. lol you can't. we already know this.

 

[pfarber]

Would you use a Jeep manual ECM? Does it need a vehicle speed sensor input? Or are you planning on a custom ECM?

aftermarket ECU. my pick so far is megasquirt. but I'm not 100% set on it. SDI makes a very good solution but isn't car motor specific (VVT or VVL etc).

I'm debating on weather to delete VVT or just disable it. Getting rid of 10lbs of metal is tempting but I have not found a bolt on replacement for the VVT block.

 

[Cap'n Jack]

If you think your air cooled motor isn't detonating just about every time you fly they you don't have the wisdom to understand ICEs, you don't fly on hot days or do climb outs lol

Not every detonation event is catastrophic. And aviation engines do everything they can to prevent it, but it still happens... you just never know about it unless its the 'big one'.

Gemini sayith:

3. In Specific High-Performance Airframes: Continuously​

Advanced engine research (such as data analyzed by organizations like Savvy Aviation and GAMI) has revealed that a few specific high-performance, factory-built turbocharged aircraft engines actually operate in continuous light detonation on one or more cylinders during standard high-power cruise settings—even when operated exactly by the factory handbook. This is usually due to uneven fuel distribution in carbureted or standard fuel-injected systems causing one cylinder to run leaner and hotter than the others.

What Does "Light Detonation" Actually Mean for the Engine?​

Contrary to popular belief, light detonation is not an instantaneous death sentence for a low-output, large-displacement aircraft engine.

• The Frequency Scale: In certification testing, "incipient (light) detonation" is technically defined as 5 to 9 explosive flashes per minute within the cylinder.
• The Impact: Unlike heavy detonation (which can melt an aluminum piston or destroy a valve train in minutes), light detonation is relatively survivable. Industry testing has shown that robust, naturally aspirated aircraft engines (producing roughly $0.5\text{ hp/in}^3$) can withstand hours of light detonation with no immediate structural damage. In fact, occasional light detonation can actually scrub carbon and lead deposits off the piston crown.

​

Citing an AI? Sorry, not valid information. An AI NEVER says "I don't know", but it will give an answer that ranges from correct to totally made up and you have no way of knowing. If you have enough knowledge to know if the answer is valid, you can also do a proper search without relying on the AI.

 

[AZEL]

 

[Doc Holliday]

PROVE. ME. WRONG. lol you can't. we already know this.

No need, you do a good job of it over and over.

The more of your inane diatribes only proves you have very little working knowledge of aircraft engines, period. Also as far as automotive we termed guys like you as "shade tree mechanics".

But please, keep digging that hole deeper and deeper.

 

[pfarber]

Citing an AI? Sorry, not valid information. An AI NEVER says "I don't know", but it will give an answer that ranges from correct to totally made up and you have no way of knowing. If you have enough knowledge to know if the answer is valid, you can also do a proper search without relying on the AI.

I cited Mike Busch from Savvy. I don't includes cites anymore cause no one reads them and just posts whatever they pull out of thin air.

If you don't think an air cooled motor isn't detonating (I NEVER SAID CATASTROPHIC) then you must enjoy your rose colored glasses.

They do... you just never, hear it.

Detonation and Pre-Ignition - SavvyAviation

Often confused and misunderstood, these two abnormal combustion phenomena are as different as night and day. Although we often hear people describe what goes on inside the cylinders of an Otto-cycle engine as being an explosion – i.e., a violent, nearly-instantaneous event – it’s not. The...

www.savvyaviation.com

I doubt you'll read it but there is it.

"In an automobile, we can usually hear detonation in the form of audible “knock.” In an airplane, we can’t – there’s too much noise – but we can observe it on an engine monitor in the form of excessive CHT and depressed EGT."

SIgh... I now know how Sisyphus felt. Lead that horse to water... can't make it drink.

Yes I mixed that metaphore.... lets see the Internet pilut commdoes rage on about that lol

 

[pfarber]

No need, you do a good job of it over and over.

The more of your inane diatribes only proves you have very little working knowledge of aircraft engines, period. Also as far as automotive we termed guys like you as "shade tree mechanics".

But please, keep digging that hole deeper and deeper.

Ah yes.. I'm so wrong you can only wax poetically on how right you are. I'll metaphorically hold my breath while you try and prove me wrong.

 

[Cap'n Jack]

I cited Mike Busch from Savvy. I don't includes cites anymore cause no one reads them and just posts whatever they pull out of thin air.

If you don't think an air cooled motor isn't detonating (I NEVER SAID CATASTROPHIC) then you must enjoy your rose colored glasses.

They do... you just never, hear it.

Detonation and Pre-Ignition - SavvyAviation

Often confused and misunderstood, these two abnormal combustion phenomena are as different as night and day. Although we often hear people describe what goes on inside the cylinders of an Otto-cycle engine as being an explosion – i.e., a violent, nearly-instantaneous event – it’s not. The...

www.savvyaviation.com

I doubt you'll read it but there is it.

"In an automobile, we can usually hear detonation in the form of audible “knock.” In an airplane, we can’t – there’s too much noise – but we can observe it on an engine monitor in the form of excessive CHT and depressed EGT."

SIgh... I now know how Sisyphus felt. Lead that horse to water... can't make it drink.

Yes I mixed that metaphore.... lets see the Internet pilut commdoes rage on about that lol

I did read the Savvy Aviation link in the post above- it is an interesting how he uses a comparison of a bomb to a gun to illustrate detonation. You certainly can't speak for me, or anyone else on this board, but I do read the few citations that you deign to share.

However, that was NOT what you originally cited- please stop gaslighting us. You cited an AI- here is your post again, with the reference to an AI highlighted:

Gemini sayith:

3. In Specific High-Performance Airframes: Continuously​

Advanced engine research (such as data analyzed by organizations like Savvy Aviation and GAMI) has revealed that a few specific high-performance, factory-built turbocharged aircraft engines actually operate in continuous light detonation on one or more cylinders during standard high-power cruise settings—even when operated exactly by the factory handbook. This is usually due to uneven fuel distribution in carbureted or standard fuel-injected systems causing one cylinder to run leaner and hotter than the others.

What Does "Light Detonation" Actually Mean for the Engine?​

Contrary to popular belief, light detonation is not an instantaneous death sentence for a low-output, large-displacement aircraft engine.

• The Frequency Scale: In certification testing, "incipient (light) detonation" is technically defined as 5 to 9 explosive flashes per minute within the cylinder.
• The Impact: Unlike heavy detonation (which can melt an aluminum piston or destroy a valve train in minutes), light detonation is relatively survivable. Industry testing has shown that robust, naturally aspirated aircraft engines (producing roughly $0.5\text{ hp/in}^3$) can withstand hours of light detonation with no immediate structural damage. In fact, occasional light detonation can actually scrub carbon and lead deposits off the piston crown.

[TR]
[td][/td]
[/TR]Savvy says:
However, in real-world aviation, light detonation is more common than many pilots realize. Because it happens on a micro-second scale inside the cylinder and cannot be heard over the noise of the cockpit, it often goes entirely unnoticed.

At least car motors are smart enough to sense knock and retard timing. Air cooled motors either live with it or die from it.

One other note: The cooling method doesn't matter regarding knock sensors as that is separate from the cooling system.

 

[Kenny Phillips]

Yes. Torsional vibration. That heavy propeller wants to turn at a steady rate, like the flywheel that it is. The engine's crankshaft does not turn at a steady rate; every time a cylinder fires it accelerates, and on every compression stroke it decelerates. This makes the gears or chain chatter, especially at resonant frequencies related to RPM, and the loads thus placed on the PSRU can be many times the load of the engine driving the prop. Belts can absorb a little more of the TV, but they can still fail. So the PSRU has to be designed to be either really stout (meaning heavy) or with enough damping and flex to absorb the TV.

In a car or truck with a manual transmission, you'll find a clutch plate with springs in it to absorb TV, but that TV is very small since it's only the transmission and driveline involved, not a heavy propeller with much angular momentum. An automatic uses a torque converter that absorbs TV since it slips anyway.

All modern automatics fully lock up in cruise, and in some acceleration modes.

 

[StraightnLevel]

All modern automatics fully lock up in cruise, and in some acceleration modes.

Sure they do, BUT, auto engines aren't running anywhere near the load factor of airplanes. The driveline has multiple dampers that don't exist on airplanes - heavier flywheel, torque converter, shock mounts on engine, transmission, differential, u-joints on the driveshaft (or CVs), and finally the tires themselves are dampers that reduce the mechanical effect of jerk on the various components. Unless you're on a racetrack or the autobahn you're probably nowhere near the peak power output of an auto engine, while the airplane runs right at peak all day every day.

As an aside, I question why anyone would expect an automotive engine to have higher reliability and/or life than an airplane engine. At 70 mph, 2,000 hours is 140,000 miles. If you drive any car 140,000 miles on the highway, holding it in a lower gear so that it stays just below redline, what do you expect from it? Is it going to tolerate that usage? What do you think the bearings and valves are going to look like?
Similarly, I'm not sure why a 2,000 hour life on Lycosaurus fan engines is seen as problematic. Again, what do you expect from a reciprocating engine?

 

[Doc Holliday]

Sure they do, BUT, auto engines aren't running anywhere near the load factor of airplanes. The driveline has multiple dampers that don't exist on airplanes - heavier flywheel, torque converter, shock mounts on engine, transmission, differential, u-joints on the driveshaft (or CVs), and finally the tires themselves are dampers that reduce the mechanical effect of jerk on the various components. Unless you're on a racetrack or the autobahn you're probably nowhere near the peak power output of an auto engine, while the airplane runs right at peak all day every day.

As an aside, I question why anyone would expect an automotive engine to have higher reliability and/or life than an airplane engine. At 70 mph, 2,000 hours is 140,000 miles. If you drive any car 140,000 miles on the highway, holding it in a lower gear so that it stays just below redline, what do you expect from it? Is it going to tolerate that usage? What do you think the bearings and valves are going to look like?
Similarly, I'm not sure why a 2,000 hour life on Lycosaurus fan engines is seen as problematic. Again, what do you expect from a reciprocating engine?

We often hear via SGOTI how someone has a automobile engine mounted on their homebuilt with "thousands of hours" but never any details such as who this person is, how much time on the engine between major maintenance, etc. The few homebuilts I'm familiar with that do have automotive engines have little time on them and have had multiple problems.

I took my Instrument checkride years ago in a 172 that had 4,000+ hours on it's O320 since new. Never had a cylinder replacement or other problems. It was a flight school airplane used extensively and had excellent maintenance. Throughout my time as an A&P/IA I have encountered many GA engines operating happy past TBO because they were maintained and not hangar queens.

 

[pfarber]

200 from TBO is a real deal-buster for an entry level purchase.

Entry level would mean 'cheap because its got issues/at the end of its life', right? Telling me an engine is 200 hours from TBO means almost nothing. I'll take that risk if the price is right. 200 hours is 4-10 years of average PPL flight hours. An IRAN without significant issues is maybe $20k... if you can afford a plane, hangar, and gas then a few more $$ per hour is not a deal breaker. $20,000/200 = $100/hr engine fund. WIth THE RIGHT PURCHASE you are still below rental rates.

As an aside, I question why anyone would expect an automotive engine to have higher reliability and/or life than an airplane engine. At 70 mph, 2,000 hours is 140,000 miles. If you drive any car 140,000 miles on the highway, holding it in a lower gear so that it stays just below redline, what do you expect from it? Is it going to tolerate that usage? What do you think the bearings and valves are going to look like?
Similarly, I'm not sure why a 2,000 hour life on Lycosaurus fan engines is seen as problematic. Again, what do you expect from a reciprocating engine?

This again? Most airplane motors die from sitting, not flying. I'll leave it to you to figure out bearing speeds and reliability of auto engines. I've posted many times that Toyota runs random engines at 100% power for DAYS and they don't break. A modern engine will run circles around an air cooled bag of bolts at max power (NOT max RPM, there is an choice to be made. My v6 plan is to derate from 260 to 200hp because bearing speeds are an issue and easy to avoid). The issue with car motors in airplanes is that every install of a car motor is basically a unique one off that depends on the knowledge of the individual to make it work. That is in the past. Anyone who does modicum of research now can get a car motor into an airplane trouble free. To the point that there is an STC for an LS engine in a 172, Diamond uses an off the shelf BMW engine, and just about any 4 cylinder Japanese engine is a shoe in for reliability if installed properly. Toyota certified a car motor but never used it. Lycoming certified a diesel.. the only reason any of these didn't come to market is cost due to obscenely low volume.

Also posting about TV.... um why do so many airplane motors have crank dampeners? Gee, you make it sound like TV is only a car issue. How many engines have RPM restrictions? Again, TV. But wait, I've just been informed this only affects car motors... lol

I do read the few citations that you deign to share.

So you admit to not reading them all...hence why I stopped... its a waste of my time and i give enough information that a simple google query will get you the same result. Other people's laziness is not my problem.

 

[pfarber]

We often hear via SGOTI how someone has a automobile engine mounted on their homebuilt with "thousands of hours" but never any details such as who this person is, how much time on the engine between major maintenance, etc. The few homebuilts I'm familiar with that do have automotive engines have little time on them and have had multiple problems.

I took my Instrument checkride years ago in a 172 that had 4,000+ hours on it's O320 since new. Never had a cylinder replacement or other problems. It was a flight school airplane used extensively and had excellent maintenance. Throughout my time as an A&P/IA I have encountered many GA engines operating happy past TBO because they were maintained and not hangar queens.

Again, for an average you will have engines in the 90th percentile and in the 10th percentile. The real number is in the middle.

SDS ignition. Of course you never read about it because you already know way more than everyone else... right? I just gave you a source of car motors with thousands of hours (considering when the artilce was written 10+ years ago) yet post like this still try and sound authorative.

EDUCATE YOURSELF before you make such easily disprovable statements.

 

[StraightnLevel]

Entry level would mean 'cheap because its got issues/at the end of its life', right?

No. Entry level means first airplane purchase.

Telling me an engine is 200 hours from TBO means almost nothing. I'll take that risk if the price is right. 200 hours is 4-10 years of average PPL flight hours.

You're joking, right? I'm a low-time hobbyist and I average closer to 120 hrs/year since I got my PPL. 200 hours from TBO means I get less than 2 years before I'm AOG for months,
Not sure where you're getting "average", but I'm guessing that it includes guys who own airplanes but don't actually fly them.

A modern engine will run circles around an air cooled bag of bolts at max power

You say that, yet the major automotive manufacturers don't seem to be able to get much past a 2,000 hour usable life. In fact, recent trends to run smaller displacement with more boost have resulted in far worse reliability in auto engines.

https://www.autoblog.com/news/downsized-efficient-but-fragile-why-todays-engines-may-not-last

There’s no escaping the fact that modern engines are failing at alarming rates. Toyota, Honda, and General Motors have all issued massive recalls involving hundreds of thousands of vehicles due to catastrophic engine failures. Engines are seizing up, catching fire, and leaving drivers stranded. Even brands with reputations for reliability are putting out engines that should last 200,000 miles, yet are barely making it past warranty periods.

there is an STC for an LS engine in a 172

How many are installed, and how many flight hours have been observed?

Diamond uses an off the shelf BMW engine,

Huh. Which one is that? The Lycoming, Continental, or the Rotax? Which specific model are you referring to?

In any case, yes, a number of planes have used BMW engines, since they started as an airplane engine manufacturer. I doubt that you're talking about the FW190 or HE162, however.....

 

[Doc Holliday]

Again, for an average you will have engines in the 90th percentile and in the 10th percentile. The real number is in the middle.

SDS ignition. Of course you never read about it because you already know way more than everyone else... right? I just gave you a source of car motors with thousands of hours (considering when the artilce was written 10+ years ago) yet post like this still try and sound authorative.

EDUCATE YOURSELF before you make such easily disprovable statements.

I don't believe I need to educate myself with regards to my statement.

You can't cite any reliable numbers on hours in aircraft with automobile converted engines because you simply don't have them and have little to no knowledge on the subject.

This is precisely what I wrote:

We often hear via SGOTI how someone has a automobile engine mounted on their homebuilt with "thousands of hours" but never any details such as who this person is, how much time on the engine between major maintenance, etc. The few homebuilts I'm familiar with that do have automotive engines have little time on them and have had multiple problems.

So please educate us and show us evidence of these high time auto engine conversions.

Or just keep moving the goal post.

 

[AZEL]

In any case, yes, a number of planes have used BMW engines, since they started as an assembler of Pratt and Whitney airplane engines... .

FTFY

 

[Cap'n Jack]

You certainly can't speak for me, or anyone else on this board, but I do read the few citations that you deign to share.

I’m not sure how you get from the statement above to your reply below this one. I’ll try again- I read all the citations you post, but you don’t post very many of them.

So you admit to not reading them all...hence why I stopped... its a waste of my time and i give enough information that a simple google query will get you the same result. Other people's laziness is not my problem.

 

[Cap'n Jack]

Diamond uses an off the shelf BMW engine

No, that’s not true. Is is based on a BMW engine, but it isn’t a BMW engine.

Austro Engine E4 - Wikipedia

en.wikipedia.org

 

[asicer]

No, that’s not true. Is is based on a BMW Mercedes-Benz engine, but it isn’t a BMW Mercedes-Benz engine.

Austro Engine E4 - Wikipedia

en.wikipedia.org

FTFY.

Oh, and BTW. https://web.archive.org/web/2025062...austro-moves-to-building-its-own-core-engine/