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Aircraft engine HP per cubic inch.

M

Mopar591

Well Known Member
Mod: I put the thread in here to get traffic.. Feel free to move if needed.

This thread isn't about the comparison of a aircraft engine vs auto engine on aircraft.

I have been building engines for cars for years.. And knowing my way around the auto engines and not having much experience with aircraft engines has raised a few questions..

1: Why is the Hp per Cube on a aircraft engine so much lower than that of any other engines with 320c.i or 360c.i.??

2: Why are most aircraft engines only capable of turning under 3,000rpm.. Prop efficiency?

3: Why is it so hard to squeeze HP out of aircraft engines vs any other engine?

Looking at engines lately just planning ahead has really got me thinking.. I mean lycoming has a 200hp IO-360 factory engine and eci has a 409c.i. Stroked engine putting out a whole 30hp more? So 48 cubic in for only 30hp... Hmmm

Please enlighten me..:D
 
You got it with #2. If the prop tips go supersonic the efficiency drops like a rock. So for most real direct coupled props that limits RPM to 2800 rpm or so.
There have been a few attempts at gear boxes (Cessna 421, I think) but they add weight and complexity.
 
I'm no A&P but ill take a stab at it.

1. Because its working at a much lower RPM and lower compression. Think about it, where's that Mopar making all its HP? Probably up at 5-6000 RPM right? Spin that lycoming up to 5000 RPM and would probably make 325hp too... Which leads to

2. Low RPM creates reliability and a flat power curve. Run that Mopar at 325 hp (or 6000 rpm) and see how long it lasts. Vehicles rarely see those rpms except for short bursts (unless its a NASCAR). However, your Lycoming is always being ran at say, 75% of its max horsepower. The lycoming should also produce its max HP for its entire 2000 hour tbo life. Maybe a new car would, but I doubt any older Car engine would maintain new HP through 2000 hrs. Also, I don't think many props would last long at RPMs up over 3000, and they'd be noisy as **** as the tips break the sound barrier at each revolution.

3. It's not. They make a lot of HP (and torque) at a low RPM. Many of the Larger displacement aircraft engines are derated to better suit their mission and increase reliability even more. For example, a skylane runs an IO-540 rated at only 235 HP, whereas a Cirrus SR22 runs an TSIO-550 rated at 315 HP.... That motors barely working in the skylane, but it ought to last forever.

Or simply put, I like to compare lycoming a to Diesels.... 150 HP in a diesel means a heck of a lot more than in a gasser.

Apples to oranges really. The real question is; why on earth does something so simple cost so gawd awful much? Sheesh!
 
But why can't they get more than a little over 200hp under 3k rpm.. Seems like there is more room for growth.. Keep the prop sub sonic and work on that rpm
Range..
 
Dbro172 said:
Apples to oranges really. The real question is; why on earth does something so simple cost so gawd awful much? Sheesh!
Click to expand...

I would love to know the answer to that also!! It's ridiculous..

I have built N/A 409ci Chevy engines that make around 600hp at 6k rpm but the one engine in particular was in a dirt car and was making 236hp At 2500 rpm. I know the prop speed and the rpm these engines have to run is a big factor.. But it's really seems like they would be able to figure out a cam profile or something that would increase performance at the rpms that it is operating in.
 
Not only the prop induced RPM limits already mentioned, but air cooling comes into play.

Then there is the need to keep the weight down....and the reliability up....and so it goes.
 
horsepower = fuel burn

So horsepower is really equal to how much fuel you can burn per hour. It has little to do with displacement alone. Even going back to WW2 radials, it seems airpcraft HP is 1/2 displacement. o360=180 Hp, 320 is about 160, PW 2800 radial is about 1400hp, with some added or subtracted for fuel injection. Now the F1 engines are only running 2.something liter displacement but they put out upwards of 700hp, but they do this at 18000 rpm with a very short stroke. Again it is how much fuel you can burn in an hour. JMHO
 
Mike S said:
Not only the prop induced RPM limits already mentioned, but air cooling comes into play.

Then there is the need to keep the weight down....and the reliability up....and so it goes.
Click to expand...

I can defiantly see cooling as a key issue... But all the technology now seems like that could be delt with..
 
The higher the displacement ultimately the higher the fuel burn also.. More cylinder volume needs more of the good stuff aka (liquid gold).. Can't disagree.

Reliability is defiantly high on the list..
 
johnny stick said:
So horsepower is really equal to how much fuel you can burn per hour. It has little to do with displacement alone. Even going back to WW2 radials, it seems airpcraft HP is 1/2 displacement. o360=180 Hp, 320 is about 160, PW 2800 radial is about 1400hp, with some added or subtracted for fuel injection.
Click to expand...

Of course, if you want to go with something more complex, you can get more...like the venerable Rolls-Royce Merlin. 1650 c.i., and

"By the end of the war the "little" engine was delivering over 1,600 horsepower (1,200 kW) in common versions, and as much as 2,060 horsepower (1,540 kW) in the Merlin 130/131 versions specifically designed for the de Havilland Hornet. Ultimately, during tests conducted by Rolls-Royce at Derby, Merlin 130 series engines generated over 2,600 horsepower (1,940 kW).[22]" (Wikipedia)

But now we're talking liquid-cooled, two-stage blowers, etc. :)
 
And just what was the reliability of the 2600 Hp merlin?
Ask an Unlimited Gold Reno Racer. It might make it through race week which probably in total is about ten hours or less of flying.

Yes, an aero engine can be made to chuck out lots of power but weight, heat, reliability and prop efficiency are all in the mix.
 
xblueh2o said:
And just what was the reliability of the 2600 Hp merlin?
Ask an Unlimited Gold Reno Racer. It might make it through race week which probably in total is about ten hours or less of flying.

Yes, an aero engine can be made to chuck out lots of power but weight, heat, reliability and prop efficiency are all in the mix.
Click to expand...

Unlimited Gold racers are running well beyond the original design. IIRC, Maximum War Emergency Power on a Mustang was something like 65" Hg, whereas Strega and her like are up around 130 or more.

If you want a more reasonable comparison, look at the stock racers (Unlimited Bronze class). Many of those planes are running the same engines they use the rest of the year, and they don't fail anywhere near as often as Dago, Strega, etc. But then again, they're using stock two-stage, two-speed superchargers, etc.

The "stock" Merlins (there are so many variants its hard to call any one model "the" Merlin) has a 500-hour TBO, which is not bad for a weapons system :) Granted, an overhaul is something like $100K+ from what I'm told, but hey...money=speed, right? :)

ETA: From the Stallion 51 website page on the Merlin:

"In the late 1950s the Mustang was released for sale to the general public. Most airframes sold had low times and warbird owners enjoyed a period of three decades where engine overhaul posed little problem, and very often a spare engine (or two) had been acquired with the airframe anyway. Overhauls undertaken during this time were similar to military schedules where the engines were disassembled, cleaned, and reassembled. Though new seals and rings were sometimes installed, major rework was just not necessary."
 
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I believe it is all about staying away from detnation, you won't hear it in an aircraft like you could in your old station wagon going up a hill in summer, (pre knock sensors) .5 HP per C.I. Has a big safty margin compared to 1 HP per C.I.
 
I have been building engines for cars for years.. And knowing my way around the auto engines and not having much experience with aircraft engines has raised a few questions..

1: Why is the Hp per Cube on a aircraft engine so much lower than that of any other engines with 320c.i or 360c.i.??

2: Why are most aircraft engines only capable of turning under 3,000rpm.. Prop efficiency?

3: Why is it so hard to squeeze HP out of aircraft engines vs any other engine?

Looking at engines lately just planning ahead has really got me thinking.. I mean lycoming has a 200hp IO-360 factory engine and eci has a 409c.i. Stroked engine putting out a whole 30hp more? So 48 cubic in for only 30hp... Hmmm
Click to expand...

Lets answer a few questions directly;

Horespower is a function of Torque and RPM. Any engine rating worthy of comparison is Torque. So a 200HP at 2700RPM is actually more torque than 400HP at 6000RPM, and when a prop has a limit due to tip speed the max RPM is important.

So you design an engine capable of the RPM you need and the torque you want, thus the HP required. Sure you can get more HP by running an IO360 at 3300 RPM, many Pitts etc do this, but there are compromises. Such an engine might give you 240HP.

What is more important is BSFC, and when I ask people what BSFC is your fancy engine giving you, and my old design Lycoming is giving me 0.39.......they go very quiet.

As for why is it harder to squeeze HP out of an aircraft engine, lots of things, as you have mentioned, at the same torque, but double the RPM, a few things need to change, least of all is the cam shaft. But lets play simple games and say an IO540 at 2700RPM can be 260 to 300HP and if we take that to 6000 RPM we get (assuming constant torque) we get 578 to 667HP. Sure that is still under 100HP/Litre, but this is a basic run all day design OK. Not F1, Nascar, V8 Supercars etc, so cut some slack.

It is also air cooled, so greater margin for detonation is required, and we are still talking about 8.5:1 CR.

So when you look at things in a realistic open mind.....the old engines are still providing, the right RPM and torque, the right long term continuous thrust, and when operated properly the right BSFC.

Hard to beat on any front.

Any questions fire away!
 
Mopar591 said:
I would love to know the answer to that also!! It's ridiculous..

I have built N/A 409ci Chevy engines that make around 600hp at 6k rpm but the one engine in particular was in a dirt car and was making 236hp At 2500 rpm. I know the prop speed and the rpm these engines have to run is a big factor.. But it's really seems like they would be able to figure out a cam profile or something that would increase performance at the rpms that it is operating in.
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That's 0.58 hp/ci on your 409 at 2500. That's not at all impossible to get from an O-360 with bigger cam, higher compression, electronic ignition or whatever (that'd be 208hp)....

Hp is just torque*rpm (and a constant)
 
Thermodynamics: The higher the pressure before ignition the more the energy release per unit of fuel. Higher compressions leads to pre-ignition. Simple and reliable air-cooled, manualy leaned, aircraft engines lack the auto equivelent systems to prevent pre-ignition. Those system (like water cooled cylinders, and electronic ignitions) add weight and un-reliability.
A typical aircraft compression ratio is 8:1. Most high spicific output auto engines are 12:1 or higher. - It is the age old engineering compromise.
 
RV10inOz said:
What is more important is BSFC, and when I ask people what BSFC is your fancy engine giving you, and my old design Lycoming is giving me 0.39.......they go very quiet.

Hard to beat on any front.

Any questions fire away!
Click to expand...

:D:D:D I find it the same David. We are getting a lot better performance from these old lyc's than a lot of people realise. There may be improvements that can be made but they need to be backed by DATA.
 
I appreciate the replies guys! I figured that there were limits to what could be made within the parameters we have to work with. Not doubting that we are getting good performance already but just wondered why the performance hasn't increased over the years. Cam profiles have cams a long way since the 60s.. Flow matching, ect..

You can't beat the reliability, weight, and the amount of hp per c.i. Giving the rpm operated in.. All in a relatively low compression ratio..

Thanks for confirming.
 
Hp on an atmo engine is mainly a function of displacement, rpm and compression ratio. If you compare a 6L Lycoming to a 6L Mopar or Chevy at say 2700 rpm, you'll see they produce about the same hp, factoring out the compression ratio.

The mission of the aircraft engine is to turn the prop at a relatively efficient rpm for a long time hence the large displacement/ slow turning recipe is common.

Engines are just air pumps really, turn them faster, they process more mass flow, boost them heavily, ditto. No magic involved.

Just as a point of interest, the Merlins in Strega and such produce over 4000hp at 150+ inches.
 
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BMEP

BMEP (Brake Mean Effective Pressure) is one of the most fundamental measures of engine performance, yet rarely discussed outside engineering circles. In broad terms, you get more power out of an engine by either increasing the BMEP or increasing the RPM. Most aircraft engines compare very favorably to high performance car engines in terms of BMEP.
For more detailed information, see:

en.wikipedia.org/wiki/Mean_effective_pressure

and

http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm

Additional Googling will display many more references.
 
Thermodynamics: The higher the pressure before ignition the more the energy release per unit of fuel. Higher compressions leads to pre-ignition. Simple and reliable air-cooled, manualy leaned, aircraft engines lack the auto equivelent systems to prevent pre-ignition. Those system (like water cooled cylinders, and electronic ignitions) add weight and un-reliability.
A typical aircraft compression ratio is 8:1. Most high spicific output auto engines are 12:1 or higher. - It is the age old engineering compromise.
Click to expand...

I think you are really meaning Detonation, not preignition. The two are very different. Damage done from heavy detonation can cause a component (usually a spark plug) to fail (usually ceramic breakage) and thus become a heat source to create preignition.

Or the failed plug can happen from being dropped and start preignition all by itself.


Wesael
I find it the same David. We are getting a lot better performance from these old lyc's than a lot of people realise.
Click to expand...

Correct!!;)
 
It's all about money. A new technology must show better total performance at a comparable price or comparable total performance at a better price. The only real alternative is a turbine, that will offer considerably better performance, but the price is way too high.
 
HP

Basicly, In my opinion the mainstream of GA aircraft are having their needs met by the standard Lycoming/Continental engine so there is little demand for improvment and little competition to drive it. Lycoming would never have offered roller cam technology if Superior had not forced them to with competition. A regular O-360 makes 0.5hp/cid an old 220hp Franklin makes 0.63hp/cid but they arent around competitivly so lycoming isnt concerned. A custom built high performance 0-360 derivatives from Lycon, Sky Dynamics, and a couple other dedicated performance shops make 0.69hp/cid so improvements are available coupled with reasonable longevity and direct drive propeller friendly RPMs however very limited volumes on a hand built basis and very high prices. Again, Lycoming isn't concerned and there really isn't meaningful competition. If a new GA engine supplier were to come to the forefront and start offering serious competition both in horsepower and price Lycoming could easily step up to the plate and offer competitive products. But unless that happens, they have no reason to do so. Russ
 
Perhaps Russel, but when you have an engine that is really quite reliable, produces a BSFC of 0.39 and is in a low volume market, how do you expect any better on both fronts? Front A is significant improvement value in a small market, and Front B is beating 0.39BSFC but anything significant.

Turbines are not in the race, not even close, otherwise they would have eaten the piston market long ago.

diesels like SMA and others..... niche only market.

It is what it is.....but folks can dream!
 
RV10inOz said:
Front A is significant improvement value in a small market, and Front B is beating 0.39BSFC but anything significant.
Click to expand...

I agree with both but may add a third. The ability to prove it is reliable with tens of thousands of hours of flight experience. Only place that may happen is in the experimental aircraft community since no certified builder will take the chance with an unproven engine.

[As much as we are used to odd shaped, funny looking aircraft, like the Long-Eze, certified builders can not sell anything that does not look like a traditional airplane, like a C172. Don't believe me look no futher then the Beech Starship and the Piaggio Avanti. Both should sell betterthen they did based on performance. Engine will be no different.]
 
plehrke said:
But what is the TBO for a turbine (compared to a internal combustion)?
Click to expand...

Philip, there is no TBO for our "Restricted" category but there is a 3500 hour "refresh" required for Part 135 operators...King Airs and such. Mine has 9500 hours SNEW and has never been majored!!

Mike, I burn 47 GPH working and around 40 GPH ferrying.

We do 1200 hour hot sections...split the engine and mic the clearance between the power turbine blades and the segmented circle that it rides in...around .0010", and examine the combustion chamber for cracks, hot spots and so on....about every three years in my case.

We do IRANs..Inspect And Repair as Necessary. Since we have a torque meter and separate engine and prop RPM indicators as well as an ITT (Inter-turbine Temp) gauge, you can somewhat monitor your engine this way and we post starts, flights and temps for each day, so we have a trending system for monitoring day-to-day.

Best,
 
Horse power and torq rating that Lycoming advertises for example: On the O-360-A4A is rated @ 180hp @ 2700rpm @ sea level. This is the mule engine that I use for testing on the Dyno. In stock configuration, only modification is a test header that incorporates wide band sensors, the most correct to sea level hp @ 2700rpm that I have seen is floats around 165hp running on 100ll av gas.
 
plehrke said:
[As much as we are used to odd shaped, funny looking aircraft, like the Long-Eze, certified builders can not sell anything that does not look like a traditional airplane, like a C172. Don't believe me look no futher then the Beech Starship and the Piaggio Avanti. Both should sell betterthen they did based on performance. Engine will be no different.]
Click to expand...
Not sure the "odd shaped, funny looking aircraft" is the true reason why the two examples you list did/do not sell large numbers of aircraft. The Beech Starship flight characteristics were different enough that the status quo at the time was unwilling to alter their perceptions to incorporate the changes. As for the Piaggio, well, an $8 million dollar twin engine turbo prop is a hard price to swallow when one could have a sexy jet, or two, for the same money.

As for me, if I had $8 million laying around I would not hesitate for one second in forking over the money for the Piaggio. That is one hot airplane that has no equal! :cool:
 
G3i Ignition said:
Horse power and torq rating that Lycoming advertises for example: On the O-360-A4A is rated @ 180hp @ 2700rpm @ sea level. This is the mule engine that I use for testing on the Dyno. In stock configuration, only modification is a test header that incorporates wide band sensors, the most correct to sea level hp @ 2700rpm that I have seen is floats around 165hp running on 100ll av gas.
Click to expand...

Thomas, something is clearly not right there. Either your dyno is wrong, which is possible or the engine is not right.

Just for curious minds, what are the engine parameters when you get the 165 corrected HP? Wot and full rich? What are the MP RPM and fuel flows? What timing? What egt and cht values are you recording?

Cheers!:)
 
Why should I be concerned with HP per cubic inch?

I am concerned with fuel efficiency and I am concerned with weight and I am concerned with durability. The Lycoming does real well on all those counts. I don't think having slightly smaller cylinders is something that would be noticeable at all or benefit me in any real way.
 
180Hp??

Thomas, You are not the first person to find that certified engine horspower is rather optimistic. Continental & Lycoming do not, to my knowledge, use SAE net standards for measuring horsepower. So if you run one of their engines on a dyno using SAE net standards you will not measure anywhere close to the claimed horsepower. I ran into this some years ago at the Diamond factory. Powerflow exhaust was advertising a 23hp increase using their exhaust system on the "180hp" IO-360-M1A in the DA-40. I asked how such a system could be legaly installed as it was my belief that the FAA would require re-certification of the airframe to run 203hp. I was informed that the engine in question accualy measures 160-163 ish on the dyno and that following a verifyed 23hp increase its dyno measured horspower was within the +5% allowable for a 180hp engine. I said hmm well I learned something about advertised vs. as installed horspower. Russ
 
Testing for HP

G3i Ignition said:
Horse power and torq rating that Lycoming advertises for example: On the O-360-A4A is rated @ 180hp @ 2700rpm @ sea level. This is the mule engine that I use for testing on the Dyno. In stock configuration, only modification is a test header that incorporates wide band sensors, the most correct to sea level hp @ 2700rpm that I have seen is floats around 165hp running on 100ll av gas.
Click to expand...

When I took delivery of my Superior IO-360 (180 HP) I was given the spreadsheet from the run-in at the factory including dyno results. Either they are lying or it is, as advertised, a 180 HP engine. That said, I don't know what HP it produces with an exhaust system and an alternator installed. That is one of the reasons why I am trying to calibrate the test "club" that was built to Jan Carlsson's specifications by Lonnie Prince, for me. I have mentioned it in previous posts and I am still trying to find a way to test the club to ensure that it is accurate.

If there is anyone out there that can put it on a dyno for me, I'll pay the shipping in both directions. Anyone? It fits the bolt pattern and size for my engine and thus for any Lyco-type 360.

With certified airplanes, they have poor induction systems, poor exhaust, etc. My induction system is capable of producing manifold pressures greater than ambient when going 200 mph. That is not rare in RV's but probably pretty rare in spam-cans. I have been unable to get Continental or Lycoming to state exactly what the test configuration was for an engine that also has a published chart.
 
n5lp said:
Why should I be concerned with HP per cubic inch?

I am concerned with fuel efficiency and I am concerned with weight and I am concerned with durability. The Lycoming does real well on all those counts. I don't think having slightly smaller cylinders is something that would be noticeable at all or benefit me in any real way.
Click to expand...

I agree, cubic inches is but one way to make horsepower, Formula 1 engines are very small, 2.4 liters, but turn 18,000 rpm. So, if you turn more rpm, you need a gearbox which is weight, so you need to make the engine lighter, in other words, reduce the displacement, it becomes a balancing act. I think the Lycoming on a power to weight basis compares very well, especially when you also consider durability as gearboxes do not have a great reputation.
 
skybolt31 said:
I agree, cubic inches is but one way to make horsepower, Formula 1 engines are very small, 2.4 liters, but turn 18,000 rpm. So, if you turn more rpm, you need a gearbox which is weight, so you need to make the engine lighter, in other words, reduce the displacement, it becomes a balancing act. I think the Lycoming on a power to weight basis compares very well, especially when you also consider durability as gearboxes do not have a great reputation.
Click to expand...

The Rotax 912 has a gearbox. It simply runs in hundreds of thousands of installations, year after year with no problems whatsoever, no cracked cylinders, no burned valves, no overheated cylinder tops etc and no destroyed gearboxes.

The Lycomings are good engines, but they are old and no new development is has been done for decades. The state of the art 6 cylinder ULPower could replace all 320s and 360s. For a slightly higher price you get a 10-20 % lighter engine, FADEC, auto fuel, smooth 6 cylinder run.
 
Your assessment of the Rotax is a little lacking in reality.

They have there fair share of drama too, and when you look at hours flown, it might shorten up the perception gap.

I love the Rotax, but it is not really any better than a good Lyc or TCM in my opinion.

BSFC is not that startling either, with a water cooled heads and better chances at detonation margin being lowered compared to an air cooled you would expect something. But even their EFI is talked about in the high 0.3's so how does that compare to say a properly set up IO540 at 0.39?

The old dinosaur engines were not so bad...even yesterday ;)
 
SvingenB said:
The Rotax 912 has a gearbox. It simply runs in hundreds of thousands of installations, year after year with no problems whatsoever, no cracked cylinders, no burned valves, no overheated cylinder tops etc and no destroyed gearboxes.
Click to expand...

I can point you to a Kitfox owner friend of mine whose Rotax gearbox seized, lunching the entire engine because of the sudden stoppage. Those additional components (cooling system, gearbox, etc) do fail from time to time, with expensive and potentially dangerous results.
 
RV10inOz said:
The old dinosaur engines were not so bad...even yesterday ;)
Click to expand...

No, they are excellent engines, but they are getting old and no development is done any more. I have personally only seen one faults with Rotax, complete loss of cooling fluid. The error was done by the installer, hopeless installation of heat exchanger-tubing. He landed safely on a small field he happened to fly over.
 
There are much hype about the Honda engine conversion, especially touting the marine's continued WOT operation is similar to aviation's requirement.
Can you tell me why the auto engine is rated at 117 hp, while the marine engine is rated at only 90 hp? Honda, with all its engineering might and technical know how, is missing something?
 
Honda Engines

Simple. The Honda car engine has a different duty cycle than the marine engine, with the marine engine having to put out 60-100% power for extended periods. Similar to an aircraft or industrial engine duty cycle. ALL engine manufacturers rate their industrial or marine engines in a similar way.
 
RVnoob said:
There are much hype about the Honda engine conversion, especially touting the marine's continued WOT operation is similar to aviation's requirement.
Can you tell me why the auto engine is rated at 117 hp, while the marine engine is rated at only 90 hp? Honda, with all its engineering might and technical know how, is missing something?
Click to expand...

A marine engine typically operates at zero alt. An aeroplane normally cruise a bit higher (less HP) and max HP is also normally time-limited.
 
Marine vs. Air

SvingenB said:
A marine engine typically operates at zero alt. An aeroplane normally cruise a bit higher (less HP) and max HP is also normally time-limited.
Click to expand...

On the other hand, marine engines have a virtually unlimited cooling capacity while liquid cooled aircraft engine cooling systems seem to be a bit problematic for many alternate engine users.

Skylor
 
SvingenB said:
The Rotax 912 has a gearbox. It simply runs in hundreds of thousands of installations, year after year with no problems whatsoever, no cracked cylinders, no burned valves, no overheated cylinder tops etc and no destroyed gearboxes.
Click to expand...

I have a friend whose Kitfox landed in a bean field after a gearbox failure. The gearbox locked up and caused a sudden engine stoppage, resulting in much more engine damage than a simple locked gearbox. IIRC, he has been told that the fix is a new engine.
 
There are more Rotax 912 around than Lycoming 320/360. Most of the Lycomings are certified, most of the 912s are not. Still, failures with a 912s are rare, failures with Lycomings are happening all the time. Maybe not catastrophic failures, but cracks and valve related failures. That is my impression.

The important thing is that there is nothing going on at Lycoming to improve the engines. They are just producing overpriced parts using manufacturing tools from the 50s and 60s. It's like the old east block countries before the wall fell. They did the same producing 50s and 60s type cars, copies from western Europe, at least they had the decency to sell them cheap. The Lycomings are good engines, the engineering done when they were designed was top notch. But thing has happened since the 60s. Cylinders don't crack anymore, valves don't burn and so on. And if they do, then things are redesigned so it won't happen again.
 
Well this has turned into quite a disscussion.. I agree that you cannot beat the reliability and weight of these engines..

Just didnt understand why they have to be so many CI to get the amount of power they do.. Seems like engineering has just came a long way from when these engines were first designed.
 
Mopar591 said:
Seems like engineering has just came a long way from when these engines were first designed.
Click to expand...

Maybe so. But the cost of engineering to fix something that isn't broken is pretty high. Add to that the cost of new engine design certification and it seems like it's easier and less expensive to stay with a proven product.

There are so many airplanes that continue to rely on these old designs that there might not be a business case to re-certify all those old planes for new engines.
 
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