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Just a thought. I am talking prop planes here. I understand prop motors in planes aren’t particularity powerful. Not sure what the balance between HP and torque needs to be. It’ll be fun to see a small block Chevy V8 flying something.
The short answer is no. The reason doesn't have anything to do with HP or Torque. It comes down to the "powerband" of the engine, lubrication, and cooling. It's the same reason that Marine engines are quite different than car/truck engines. Aircraft engines are designed to operate in a specific RPM range for long periods of time. They have oil pumps that are tuned for this as well. The cooling system is also fine tuned for this. Regular automotive engines are designed to operate over a wide range of RPM's. So an automotive engine would be very inefficient in an aircraft. The other consideration is weight. Aircraft engines go to great lengths to be as light as possible. Automotive it doesn't matter.
I read a long time ago about a kit car that someone placed a V-12 from an WW2 era aircraft into. The project was a bit of a disappointment because although the engine produced 1,500 HP, it was in a narrow RPM range. I think it was 8,000 to 10,000 RPM. The engine produced virtually nothing below 3,000 RPM. The engine also revved slowly. It wasn't fun to drive at all.
I know someone who, being cheap tried to use a 350 truck motor in a boat. The water pump in the engine had an entire lake of cold water to use, so the engine never made it to a normal operating temperature. It caused the oil to become contaminated with water vapor, and the engine locked up after only a couple of months.
Yeah, a lot of kit planes have been built with air-cooled VW and Porsche engines. Ideally they get different cams since as noted an av engine works in a narrow and probably lower than you think RPM band, and I think in some cases are required to have magneto ignition (considered more reliable) and maybe dual magnetos - but alloy automotive motors have been put in airplanes.
Look at the engine in the Wright Flyer - looks a lot like typical automotive motors of the day.
An iron V8 would tend to be on the heavy side for av use, if nose mounted would be hard to balance out, you might need to put it amidships like a P-47.
The guy with the 350 in the boat simply did it wrong. If the proper restrictors are used, a V-8 in a boat runs at normal operating temperatures just like in a car or truck. Best in a boat to run a closed antifreeze system and a heat exchanger if you want to reject heat to the lake.
Subaru is the automotive division of Fuji Heavy Industries Ltd. (FHI) of Japan and they produce automobiles with a horizontally opposed or boxer type engine. And its is also used by aircraft builders and some small companies to convert this into an aircraft engine. Eggenfellner and Stratus, for example, have been doing this for years and they have created a very fine product.
Like Rotax, Lycoming and Continental Subaru realized that a horizontally opposed engine has less natural vibrations to compensate than an in-line or a V-engine. In cars this design results in an engine that has a lower center of gravity. For aircraft installations it means that the cowling has a lower profile and thus less drag, a very desirable property if you want to reduce fuel consumption by streamlining the cowling.
The short answer is no. The reason doesn't have anything to do with HP or Torque. It comes down to the "powerband" of the engine, lubrication, and cooling. It's the same reason that Marine engines are quite different than car/truck engines. Aircraft engines are designed to operate in a specific RPM range for long periods of time. They have oil pumps that are tuned for this as well. The cooling system is also fine tuned for this. Regular automotive engines are designed to operate over a wide range of RPM's. So an automotive engine would be very inefficient in an aircraft. The other consideration is weight. Aircraft engines go to great lengths to be as light as possible. Automotive it doesn't matter.
I read a long time ago about a kit car that someone placed a V-12 from an WW2 era aircraft into. The project was a bit of a disappointment because although the engine produced 1,500 HP, it was in a narrow RPM range. I think it was 8,000 to 10,000 RPM. The engine produced virtually nothing below 3,000 RPM. The engine also revved slowly. It wasn't fun to drive at all.
I know someone who, being cheap tried to use a 350 truck motor in a boat. The water pump in the engine had an entire lake of cold water to use, so the engine never made it to a normal operating temperature. It caused the oil to become contaminated with water vapor, and the engine locked up after only a couple of months.
I have a buddy whose father built and raced boats in the 50-60s. He learned from him and currently has a 17' jet boat with a Ford 427 pro street engine in it. I'll have to ask what he did to make it run in the boat. It has the typical cooling/exhaust setup from what I have seen of it. It is fast as hell and too much fun to drive. There is nothing like a hard right turn in a jet boat at 60 mph. Engine is a loud beast.
Can auto engines power aircraft, yes they can. Is it smart to use an auto engine to power an aircraft, no it isn't. Most the people that have built home made kit planes with VW engines have converted them to aircraft engines because the auto engines fail fairly fast.
Auto engine spend most of there life at 35% power or less. Aircraft engines operate at 75% to 100% power.
Has any one wondered how the aircraft manufactures come up with a TBO (Total Before Overhaul) hours. Here's how they do it, when they have a new designed engine they but the engine on a test mount and run it at 100% power until it breaks (non stop), then they fix what broke and then run it again until it breaks again. Most aircraft engines will run 1500 hours or more before they fail. Auto engines barely make it 500 hours at full throttle before a catastrophic failure.
Porsche actually made an engine for aircraft based on their best auto engine. It was proclaimed to be the most fuel efficient engine for aircraft. After about a year they pulled the engine because of too many failures.
Can auto engines power aircraft, yes they can. Is it smart to use an auto engine to power an aircraft, no it isn't. Most the people that have built home made kit planes with VW engines have converted them to aircraft engines because the auto engines fail fairly fast.
Auto engine spend most of there life at 35% power or less. Aircraft engines operate at 75% to 100% power.
Has any one wondered how the aircraft manufactures come up with a TBO (Total Before Overhaul) hours. Here's how they do it, when they have a new designed engine they but the engine on a test mount and run it at 100% power until it breaks (non stop), then they fix what broke and then run it again until it breaks again. Most aircraft engines will run 1500 hours or more before they fail. Auto engines barely make it 500 hours at full throttle before a catastrophic failure.
Porsche actually made an engine for aircraft based on their best auto engine. It was proclaimed to be the most fuel efficient engine for aircraft. After about a year they pulled the engine because of too many failures.
That would have been the Porsche-powered Mooney I imagine.
Of the aircraft that I've flown (a couple dozen smaller planes), maximum continuous power has been 75%, and full power was only approved for short bursts, such as take-off roll and initial climb. Of course, "full power" is usually considered full throttle at sea level with standard air temp and barometric pressure, as power declines with pressure altitude and heat (thinner air, less oxygen).
On a summer day in Wyoming, it's tough to get 75% power even on the ground with a normally aspirated engine. For more fuel-efficient flights, I usually cruised at 10,000-12,500 feet asl where full throttle gave me 50-65% power, iirc. (I no longer fly.)
For several years I was involved with the Experimental Aircraft Association. Several builders used various car engines in their homebuilts. I was never crazy about water-cooled engines for planes after the father of a friend of mine was scalded to death when a water hose burst in the P-51 he was flying.
So much nonsense in above responses, it's almost too funny.
1) Aircraft engines use up to 100% of their rated power (one must derate actual developed HP per density altitude, this is significant for those of us who fly from high altitude airports ... my base is at 6,000' MSL, so it's a big deal hit on performance) for take-off and climb operations. Otherwise, most GA aircraft engines are operated at 75% max HP for cruise, and many pilots will choose to operate at 65% HP for cruise to conserve fuel with a modest trade-off for reduced cruise speed.
2) Time/speed/fuel consumption calculations are a major aspect of GA flight, especially for an owner/operator who gets to pay for the operations and any mistakes leading to shortened engine life or increased operating costs. For those who don't need to push their cruise performance or wish to extend maximum distance without refueling, it's not uncommon to run their engine at substantially lower %'s of rated HP ... my C182 owner's manual includes "maximum range power settings" tables down to 34% (achieved at 2000 RPM and 14" manifold pressure) at 15,000' (which isn't an unusual cruise altitude for me if I'm cruising taking advantage of strong tailwinds for a few hours). The advantage is about 100 miles further cruise distance on full tanks and a reduction in published speed from 150 mph (at 54% HP) down to 101 mph. The speed reduction can be more than offset by favorable tailwinds at altitude, not uncommonly 50-100 mph to restore my over the ground speed into normal to well faster than normal traveling speeds.
at most of the altitudes that I fly, and many times it's only 2,000' AGL ... it's impossible on a warm day to achieve 65% HP at cruise RPM's. I do a lot of flying at 50-55% at WOT and I'm thankful to get that much, especially on those days when I'm up against our Rocky Mountain area headwinds.
3) numerous automotive engines have been successfully used in aviation applications. VW air cooled engines have been used for decades in small aircraft, and Subaru flat-4's have been used quite successfully in recent years, too. Note that the Subie's are water cooled engines and the details of that have been quite well worked out by a number of aircraft modifiers. There are a few models of experimental/home built craft that have been very favorably operated with these engines; the power/weight ratio has been acceptable and the performance with specific fuel consumption has been well received. There have also been a number of V-6 and V-8 automotive engines with the appropriate cooling systems engineered which have proven themselves in the experimental aircraft biz. The advantage to all has been that the engine cost is much less than certificated aviation engines, and the automotive technology is pretty far advanced over what is available in Continental or Lycoming (or Franklin, or a whole host of other aviation engines with their origins in the 1930's). Even if the service life before being worn out and needing overhaul is shorter than in a certificated engine, the net cost per hour is much less.
A big detail in using these engines is the reduction gearing from the crankshaft to the propeller RPM, where you typically will operate in a 2,000 to 2,500 RPM range. Much depends upon the propeller design, pitch, and diameter ... and what you're seeking in take-off, climb, and cruise performance for a given airframe. Some matches prove to work well, some don't. You usually won't know what's "best" unless somebody has already tried a given combination and you can work from their results.
But the biggest wear area of using these engines is the reduction gearing, not the engine hard parts.
4) The Porsche PFM/Mooney combination sucked, big-time. All that vaunted Porsche engineering with higher HP per specific fuel consumption with a fan-cooled air cooled engine was poorly done. The engine was turning high RPM to generate the rated HP on a relatively small displacement engine. The concept was to take advantage of a smaller more fuel efficient engine. In reality, it weighed as much or more installed than the certified engines it replaced. It achieved it's improved fuel consumption per hour at the cost of a slower aircraft (which meant it was actually producing less HP than it was advertised to produce). In side-by-side flight tests, the PFM powered aircraft could keep up with the certified Mooney aircraft only by upping their fuel consumption (and RPM, IIRC) to where they were using more gallons/hour than the certified aircraft engines.
Porsche had high hopes and marketing push to install the PFM engines into Cessna aircraft, with a target of the 182 marketplace (and hopefully, retrofits into legacy 182's). The reality was that the PFM in a 182 yielded far lower cruise speeds when it achieved lower fuel consumption. To keep up with the original test bed 182 performance ... well, my understanding was that it never was able to do it, no matter how much they (Porsche) tweaked the motor. They were up against an O-470S Continental engine that weighed less and ... on paper ... made less HP per gallon of fuel per hour than the Porsche. I wouldn't go so far as to say that Porsche lied about their numbers, but they sure didn't make any friends in the Cessna camp ... and there were a lot of Cessna owners who'd love to find an alternative to the short top end life of the big-bore Continental engines in service.
Porsche's cost per motor, premature short life, and maintenance costs far in excess of the Continental or Lycoming motors they were targeting sank that program, much to Porsche's chagrin and embarrassment. My understanding was that Mooney bought back a bunch of the airplanes, and Porsche offered to exchange failed engines at a specified price in the planes that continued to fly with that engine. The cost, performance, maintenance, and wear was a total bust. And Porsche was no stranger to aviation, nor to understanding design/performance requirements in building an engine for a specific purpose. Supposedly, they dedicated a sizable team and engineering man-hours to craft their aviation dedicated product and really came up short.
5) TBO is, at best, a wild-eyed guess on the part of the manufacturers. The original spec aren't rigorously determined by running engines on test stands for hours to failure, they're determined by a conservative guess by the manufacturer based upon many assumptions of how the engines will be used. Typically, those initial TBO specs are modified as engines come in for overhaul/repairs and the wear amounts are documented from actual service to show that the engines can and will deliver satisfactory service for far longer hours.
It wasn't until recent years (perhaps a bit more than a decade or so) that the fallacy of operating "past TBO" has been more carefully reviewed and rejected. Why so? because years ago airworthiness requirements effectively mandated that is was "unsafe" to operate past that magic number. For GA certified aircraft in commercial service, it's still a mandatory number to observe. But private GA operators, and some fleet operators, have proven that the TBO numbers were a joke ... an expensive joke foisted upon GA owners.
There's a lot of aircraft engines that are operated and maintained far past TBO, even in severe service.
Typical example: an O-470R Continental engine in a C182 has a 1,500 hr TBO. This has never been changed. Yet, even back in the day when I bought my C182 over 30 years ago, private owners inspecting and maintaining the engines "on condition" were achieving 2,000+ hrs on these engines. Why was the original TBO set so low? Continental's story was that this engine used in a 182 could be subjected to all kinds of shock cooling and abuse in training flights or in other ham-fisted operator's hands. I know folk to this day who put on a lot of hours per year and plan to replace a perfectly fine running O-470 at 1,500 hrs with a factory zero-time reman when they're getting close to that number. And yet, back when I bought mine ... fish spotters and pipeline or powerline patrols were flying 2,000+ hours with good service, normal power, normal oil consumption ... and when the engines were torn down for overhaul, the parts were inspected. Cleaned, measured, magnafluxed, xyglowed, x-rayed ... you name it, all the normal stuff aviation requires to "yellow tag" a part for return to service. Ya' know what? those engines were showing that the parts could still be safely run. Yes, the wear items needed to be replaced ... bearings, seals, pistons/rings. But I've seen numerous 2,000+ hour cylinders that still measured within specs and could be returned to service with a light honing to seat in new piston rings (and I've got 6 of them on my O-470R ... who knows how many hours total on these cylinders which came on the factory 0 timed overhaul that the owner installed prior to me buying the plane? I've put over 2,000 hours on those cylinders since I bought the plane, and yes ... they've all been off the engine at least once to overhaul them, but they're still flying and within specs)
OTOH, put that O-470R in a number of other aircraft and Continental rates it for 1,800 hours TBO. As well, a number of aftermarket engine modifiers have gotten FAA approval for 2,000 hours on what is effectively the same engine components as the original factory items ... in some cases, with mods that extract more HP but still use the original engine rods/crankshaft/cylinder heads.
Similarly, I've seen many Lycoming engines in Piper and Cessna aircraft that have been run hundreds of hours past TBO with excellent service and still ready to go more hours. Pilots are doing so in recent decades with confidence. How so? well, the first aspect of this is that in-flight engine monitoring is now a common item in the industry. Folk get to more closely observe and record engine temps and fuel mixtures and ignition performance under load, in flight. Borescope examinations are now more detailed, and the "art" of looking at exhaust valves and analyzing the colors of valve/seat burning is now common knowledge. You can look at a valve and determine it's likely service life remaining, or when it's at a point when it needs to be overhauled; years ago, a "compression" test was the be-all and end-all of such a diagnosis. And the required figures bore little relationship to the safe remaining service life of these items. (Check out Mike Busch's articles on diagnosis and "on-condition" engine analysis and repairs ... years ago, his positions would have been heresy, now they are gaining ... if they haven't already been ... acceptance. At the cost of aviation maintenance and repairs, unneeded expenses aren't tolerated so easily anymore).
6) Marine use of automotive engines has a long history of many successful powerplants, with untold millions of hours of excellent service. Take your pick, gas or diesel engines abound.
Marine modified, but essentially the main engine block/crank/cylinder head/fuel system ... wow, where to begin?
Detroit Diesel engines marinized as Graymarine diesels. From lowly 3-53's all the way up through V-12's, with a stellar history of performance/fuel economy in civilian, military, and commercial use for decades. These were a very popular fishing boat engine for decades.
Cummins Diesel ... a highly successful contemporary use is virtually the same engine as found in a Dodge pick-up truck, yes ... the in-line 6.
Caterpillar ... 3406's, and so many others in their line-up. A major player in the marine propulsion industry.
And many others that were designed as automotive engines. Not unusually, many have higher HP ratings in their marine versions than the USA emission controlled road versions.
Gasoline engines? Ford 460's Chevy 454's and 350's. Incredibly popular engines for marine service for inboard power plants, for decades. You probably would have a hard time finding power boats in the mid 20' to 35' range of the 1960's-70's-even the 1980's that didn't use these engines with stellar performance and service lives.
When the marine industry went to a lot of inboard/outdrive power plants ... automotive engines were still the first choice. Again, many Ford, GM, Volvo ... and a host of others ... are the engines in a lot of pleasure craft. Simple mods for water pumps, exhaust manifolds, compression ratios, make a "marine" conversion simple. Oil pans may need to have a different shape, but that's another easy mod and not a fundamental change of the engine. I got to overhaul a carb on a 4-cylinder Mercruiser engine this summer (as an emergency for a friend's fishing trip here in Wyoming ... and the carb was a slightly updated item from the familiar two-bbl Motorcraft carb of decades ago). The starter and alternator on it were standard automotive items ... and both also needed replacement on this trip (funny how that works out ... your "friends" come out for a visit/fishing trip and the next thing you know, you're taking care of their multi-years deferred maintenance items so that you can enjoy the fishing company).
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