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which auto engine can run at full power for long periods?

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Himat

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I'm thinking that putting the engine in a plane is outside the manufacturers recommendations.
Ron
Definetively!:)

But as long as the engine is operated within safe working parameters, car, truck, boat, plant or aircraft does not matter to the engine.
 

Himat

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Then they've derated the engines. I got my specs here:
The Ford 351 Windsor & Cleveland Engine Specs

50°C is really hot weather. The engine will run warm and won't produce anywhere near rated power. At 50°C (122°F) at sea level, the density altitude is about 3700'.

Dan
I think the specs you got is from pre 1973 muscle cars. Hauling a F150 is a different use and Ford obviously have derated the engine.
Which make me think about car engine use. The Paris - Dakar rally used to have a "production" class for unmodified cars.
One I did read about in a 4WD magazine was in the mid 1980'ies. They bought a Izizu Trooper 2.6 petrol, loaded it with spares and equipment and headed for Dakar.
They finished (rolling the car at least once), and noted that in soft sand they had to back of the throttle a little to not overheat the engine.

A candidate for a cheap 130hp engine:
What about the Alfa Romeo 2l twin spark?
Aliminum block and ready for redundant ignition system.
Only trouble is that 130hp is at 5000rpm, this is the max torque rpm, in a car it's rated 143hp @6000rpm . A reduction drive is then needed.
(To get 130hp at aircraft propellor speed, without turbocharging a engine size of 3.5l or more is needed.)
 

Dan Thomas

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(To get 130hp at aircraft propellor speed, without turbocharging a engine size of 3.5l or more is needed.)
The 3.3 litre engine in my '06 Hyundai Sonata is rated at 287 hp at 6500 RPM (Canadian rating; California's is 12 hp less). With a PSRU losing maybe five or 10 percent it would still produce 250 hp.

But I wouldn't expect it to live a long time at that output. I see abused cars all the time; rattling, clunking, smoking vehicles whose drivers are forever using all the throttle to accelerate away from the lights.

Dan
 

Vigilant1

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A candidate for a cheap 130hp engine:
What about the Alfa Romeo 2l twin spark?
Aliminum block and ready for redundant ignition system.
Only trouble is that 130hp is at 5000rpm, this is the max torque rpm, in a car it's rated 143hp @6000rpm . A reduction drive is then needed.
(To get 130hp at aircraft propellor speed, without turbocharging a engine size of 3.5l or more is needed.)
An Alfa Romeo? Probably not a good choice for anyone living int he US (they are a rarity). And, unless their engineering/quality has changed a lot in the last few decades, I can't imagine flying behind an Alfa engine. My Triumph Spitfire was a paragon of reliability compared to the Alfa Romeos of the time.
 

Himat

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The 3.3 litre engine in my '06 Hyundai Sonata is rated at 287 hp at 6500 RPM (Canadian rating; California's is 12 hp less). With a PSRU losing maybe five or 10 percent it would still produce 250 hp.

But I wouldn't expect it to live a long time at that output. I see abused cars all the time; rattling, clunking, smoking vehicles whose drivers are forever using all the throttle to accelerate away from the lights.

Dan
Maybe I was not particualarly clear, to get 150hp at a crankshaft speed of 2500 to 3000 rpm (typical aircraft engine?) the engine need to be of the same size as an aircraft engine. An O-320 series engine is 3.875l and is rated somewhere like 150hp at 2700rpm. As as far as I remember the thermodynamic class, the torque of a four cycle normally aspired petrol fuelled internal combustion engine is set by the mean combustion pressure and size of the engine. Mean combustion pressure is more or less the same on all engines if the design is ok and the induction system not suffocating the engine. Power is the product of torque and angular speed (rpm). In the end, to get a certain power at a specified rpm the volume have to be larger than specific minimum.

To get more power of an engine with a given capacity there is two options.
Make it spin faster or raise the mean combustion pressure by supercharging it.

Example:
An O-360 is rated 180hp @2700 rpm (Wikipedia).
An Ford 351 "H" is rated at 355 ft. lbs @ 2600rpm (your source) wich gives 175hp @2600rpm.
Same source rate this Ford 351 at 177 and 250bhp @4600rpm, it do look like the torque fall significant at higher rpm.
The Ford 351 "W" is rated at 380 ft. lbs @ 3400 rpm, gives 246 hp @3400 rpm. Max is 340hp @5400rpm.

The O-360 might give 250bhp @4600 rpm, but i suspect only for a short while.
 
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pie_row

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To get more power of an engine with a given capacity there is two options.
Make it spin faster or raise the mean combustion pressure by supercharging it.
Pump more air. Here is the way I look at Hp. Piston area time average piston speed times Ve time Me times Te times a bunch of stuff at the end to make it work out in Hp gets you Hp. IF you want more hp then you need more piston area, more average piston speed or more Ve. More Ve is the lightest way to add more power to an engine. A shorter stroke with a re-drive is lighter than a longer stroke without a re-drive for the same average piston speed.
 

Himat

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An O-320 has 320 cubic inches, which converts to 5.24 liters.

Dan
Thank's spell checker missed that one.
(I must have confused the numbers as I did not convert them at the time.)

Anyway, your 3,3l (204cu. in?) Hyundai engine isn't that bad.
From an internet source I find 235hp @6000rpm. (Different source, market...)
226 ft. lbs @3500rpm, which translates to 150hp @3500rpm.
At 3500rpm even a Hyundai should last if maintained.
That O-320 need another 2l capacity to get the same horsepower at 800rpm less.
You can rev the car engine past 6000rpm without destroying it, I would not try that with an aircraft engine.
 

Dan Thomas

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You can rev the car engine past 6000rpm without destroying it, I would not try that with an aircraft engine.
No, the aircraft engine wouldn't like 6000 RPM. Valves would have floated long before that anyway. The racing guys do hop up aircraft engines and run them at 4000 RPM, though. O-200 and the like in the Formula racers, with little short props. An O-320 is typically rated at 2700 because that's what the usual propeller bolted to it can take. Overrevving an engine is always harder on the prop than the engine; the centrifugal forces increase by the square of the increase in speed. Lycoming (engine) and and McCauley (prop) recommend inspections for any overspeed of 10% that lasts more than, IIRC, 5 seconds. The prop especially, needs an NDI to look for stress cracks. A 10% overspeed increases the centrifugal forces by 21%. 20% overspeed increases them by 44%. You can see that the prop, which is already the most highly stressed part of most airplanes, could suffer.

Dan
 

autoreply

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And to add to Dan's remarks; Formula 1 completely bans metal props and a major part of the regulations talk about what the prop must be able to endure.
 

Topaz

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No, the aircraft engine wouldn't like 6000 RPM. Valves would have floated long before that anyway. The racing guys do hop up aircraft engines and run them at 4000 RPM, though. O-200 and the like in the Formula racers, with little short props. An O-320 is typically rated at 2700 because that's what the usual propeller bolted to it can take. Overrevving an engine is always harder on the prop than the engine; the centrifugal forces increase by the square of the increase in speed. Lycoming (engine) and and McCauley (prop) recommend inspections for any overspeed of 10% that lasts more than, IIRC, 5 seconds. The prop especially, needs an NDI to look for stress cracks. A 10% overspeed increases the centrifugal forces by 21%. 20% overspeed increases them by 44%. You can see that the prop, which is already the most highly stressed part of most airplanes, could suffer.

Dan
Not to mention prop efficiency drops radically at large RPMs, unless the diameter is small - which increases the disk loading and so efficiency drops anyway. Not much point in spinning a conventional propeller beyond the point where the tips go sonic. All you're really making at that point is a lot more noise, with not much extra thrust.
 

GaryBuster

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My Mazda bridgeported 12a was dyno'd at 209 hp at 7500 rpm... and would do that all day long with a 2.85 PSRU. The tandem gyroplane was ALWAYS flying "non-stop" at the fly-ins giving rides!! I'm looking forward to peripheral porting a renesis on my next tandem gyro I build. Again.. I'll spin it at 7500 rpm max and lug around the airport about 5500 rpm.
 

litespeed

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I will just jump in here,


After that comment on the old Alfa Engine.

These engines were built in one form or another for about 40 years and were still a very good thing.
The problems they have are either the modern crap that all cars seem to have or poor maintenance.

They have done twin plug heads, fuel injection and even variable valve timing since the early seventies.

I have had and loved alfas since my misspent youth, and the engine itself- not bad tuning or spagetti electrics is one hell of a tough bastard.

They are all alloy- heads, block and big (6.6lt) sinned sump.

Twin cam, twin row chains- not belts. Very light but rigid block, and strong forged rods, pistons, crank.

No problems with burnt exhaust valves- sodium filled valves were standard.

Last one I was a 78 model with over 300,000km hard driving- bugger could not be killed-

Cold morning- push the throttle once (quad choke carbs) and start- every time.

In the end, the spare low km motor had a find a new home- no need.

Yes it used oil, but they are designed that way and not much more than new. Aero engines are the same.

For a engine that is simple, rugged as hell but wonderfully engineered a old Afla two valve with twin plugs and modern injection would be hard to beat.

130hp at 5000rpm and big wide torque band so it makes good power at low revs- 2800 prm say if without a psru.

With a psru it would be great as a light and efficient, uncomplicated engine that has reasonble cubes so doesn't have to work too hard.


The SAAB would be a good candidate- that motor was built and designed in the pre GM days- when SAAB cars was something to occupy spare capacity at the Aerospace company.

Oh and Alfa was a major aircraft engine maker when the above motor was designed......................spooky.
 

litespeed

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If you have a bigger design that needs more grunt and want a direct drive?

Nothing beats cubic inches- then its only a matter of how to get em and still be light and smooth- less pulse for the prop and prsu.

My vote...........

BMW V12 M70 from the e34 and e38 seven series.

Actually amazingly light- 5 litres and 300hp at 5,500rpm.

All alloy construction and 60 degree- very small for its size and has been designed to pull a 2 plus tonne limo at 200km/hr plus crossing Europe.

If it can punch a limo through air a big speed hour after hour- its designed well. Heads are perfect for aero use as they are designed for maximum torque not revs. So big fat prop turning power is available at low revs, like a big block v8 but super smooth and far better suited.

The M70 is actually lighter than the six used in the same car. I will take twelve pots every time.
 
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Comparing NASCAR Cup engines to Formula One engines, by EPI Inc.
"At the end of the 2006 season, Formula One engines typically used a 20,000 RPM redline (sometimes even throughout the course of a Grand Prix), and produced a peak power of about 755 BHP at above 19,000 RPM, with a peak torque of about 214 lb-ft (290 nm) at 17,000 RPM.
NASCAR "Cup" engines, by comparison, are the opposite end of the regulation spectrum. Not only are they more tightly restricted with regard to allowable parts, materials, dimensions, component minimum weights, etc, they must be derived from a (nominally) production-based, iron-block, 90° V8 with pushrod valve actuation, two valve wedge heads and a single four barrel carburetor. These engines are subject to various parameters imposed by NASCAR upon the four competing manufacturers in addition to those in the published rule book.
Of particular note, the Cup V8 is restricted to a 106.3 mm (4.185 inch) maximum bore, a 5.86 liter (358 cubic-inch) maximum swept volume, a 90° crankshaft, steel conrods, a single valley-located camshaft, flat tappet cam followers of no more than 22.2 mm (0.875 inches) diameter, pushrod & rocker-arm valve actuation using steel pushrods and aluminum or steel rockers, (approved) aluminum cylinder heads with two valves per cylinder using steel helical valvesprings, a single four barrel carburetor based on a specified Holley model and a single, distributor-controlled ignition. Engine weight is approximately 260 kg (575 lbs).
Each car must, by regulation, use the same engine for one complete race meeting (practice, qualifying and the race) or be penalized. Races are typically 300 – 500 miles in length, so the design life of an engine is up to 800 miles.
At the end of the 2006 season, Cup engines made peak power of about 820-830 BHP at about 9000 RPM, and peak torque of about 520 lb-ft at about 7500 RPM. During a typical oval race, these engines continuously cycle between about 7000 and 10,000 RPM. (I have it on very reliable authority that, if it were not for the final drive gearing rule, today’s Cup engines would be operating close to 11,000 RPM.)"
 

Topaz

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The issue of RPM with aircraft is less about engine life and more about prop efficiency. It drops dramatically as the tips go supersonic, which happens at surprisingly low RPMs for practical prop diameters.

Once you go beyond a certain point, your engine is turning more of its gas into noise than additional thrust.
 

Dana

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The issue of RPM with aircraft is less about engine life and more about prop efficiency. It drops dramatically as the tips go supersonic, which happens at surprisingly low RPMs for practical prop diameters.

Once you go beyond a certain point, your engine is turning more of its gas into noise than additional thrust.
That's why there are redrives....

-Dana

If ignorance is bliss, why aren't there more happy people?
 

Topaz

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That's why there are redrives....

-Dana

If ignorance is bliss, why aren't there more happy people?
Exactly. Which, as we've seen before, is a very good way to turn an "inexpensive" auto-engine project into a very expensive airplane engine project, especially at the power levels being discussed here.

I'm happy with auto conversions for the lower end of the power spectrum. For racing engines, though, it just seems like buying trouble, IMHO.
 
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