Finicky Plane Engines.....Why not a proven Auto?

[Dave Krall CFII]

Yeah, liquid cooled... gotta watch that in aircraft engines! Like in the P51 Mustang, what a water cooled lemon THAT turned out to be!

In reality, perhaps the epitome of liquid cooled airplanes, the Mustang proved during the war and continues daily to this day to prove, the advantages of getting the most HP out of its engine by utilizing the superior cooling traits of liquid cooling. It obviously has to be done right, as do most things in aviation, to be really successful.

 

[Hiperbiper]

I'd like to see a Jaguar V-12 in a small P-51 replica. It should at least sound decent. Failing that, an old Navion converted to a taildragger and having a 350 with a redrive on its nose should get the blood going about as well.
Dan;
No on both counts!
At different times I owned 2 V-12 XK-E's. One a convertible and one coupe.
All I can say is there was a reason why, shortly after it was imported into the US in the '60's there was a conversion kit for the Chevy 350! The Jag V12 was a POS!.
As to the Navion...well NO!

JMPO
Chris

 

[steingar]

Yeah, liquid cooled... gotta watch that in aircraft engines! Like in the P51 Mustang, what a water cooled lemon THAT turned out to be!

In reality, perhaps the epitome of liquid cooled airplanes, the Mustang proved during the war and continues daily to this day to prove, the advantages of getting the most HP out of its engine by utilizing the superior cooling traits of liquid cooling. It obviously has to be done right, as do most things in aviation, to be really successful.

O.K., but you have to figure out where to put the radiators, water pumps, and all the other stuff every time you use a car engine. And plenty of Mustangs came down because their radiators got shot out.

Sure, if there were no FAA and 15K airplanes/company/year coming out, there probably would be some super liquid cooled system on airplanes. Theilert started out as a Mercedes engine, if I recall correctly. Heck, there's a liquid cooled engine on my sportbike and the bike is lighter than my last air-cooled one. But airplanes are only produced at a trickle, and we're stuck with engines from the stone age being the best thing available.

 

[Dave Krall CFII]

O.K., but you have to figure out where to put the radiators, water pumps, and all the other stuff every time you use a car engine. And plenty of Mustangs came down because their radiators got shot out.

Sure, if there were no FAA and 15K airplanes/company/year coming out, there probably would be some super liquid cooled system on airplanes. Theilert started out as a Mercedes engine, if I recall correctly. Heck, there's a liquid cooled engine on my sportbike and the bike is lighter than my last air-cooled one. But airplanes are only produced at a trickle, and we're stuck with engines from the stone age being the best thing available.

For now, I am betting my slant 4 turbo's (Garret) liquid cooled plumbing won't get shot out while I'm airborne in it but who knows? I think I'll still arm the aircraft well to help prevent that...

Easy to figure out radiators placement, they're right where the Mustang's were, for many of the same reasons.

 

[Hiperbiper]

Yeah, liquid cooled... gotta watch that in aircraft engines! Like in the P51 Mustang, what a water cooled lemon THAT turned out to be!

In reality, perhaps the epitome of liquid cooled airplanes, the Mustang proved during the war and continues daily to this day to prove, the advantages of getting the most HP out of its engine by utilizing the superior cooling traits of liquid cooling. It obviously has to be done right, as do most things in aviation, to be really successful.

Dave; you are right in one way, the P-51 was the most formidable liquid cooled ride in the entire WWII (which is not to dis the British Tifffe with it's 24 cylinder liquid cooled noise maker). However; it's losses during the latter 1944 and the first of 1945 marked is as inferior to the radial engined -47's and British Beaufighters during ground attack (the most common duty at the time) due to it's need for a cooling system. One bullet in the radiator or the piping that ran thruout the BELLY of the -51 brought you down. Soon. And in the Enemy camp.
My dad was shot down strafing a German 'drome in Febuary of 1945 in a P-51B. He always said if he hadda' been in the 'bottle (the slang term for the P-47) he would have gotten back...and he absolutly HATED the P-47...*

In our world, if air will cool the cylinders to the required temps then the liquid cooling system does exatcly...what?
The Spit, Hurri, Tiffi, Mustang, 'Cobra NEEDED cooling that could only be offered by liquid cooling systems due to designed form drag requirments.

I myself love innovation. To replace something with something that's different, not better, well; that is just being different. Not Innovative.

Just my Rambling thoughts.

* Kendall E. Carlson 336 FS 4th Fighter Group
Chris

 

[wanttaja]

OK, home now, took a look at my databases.

My January 2008 FAA registration database has 30,376 aircraft registered as Experimenta/Amateur-Built.

There are 599 aircraft registered with Subaru engines, of which 561 are experimental/Amateur-Built aircraft. There's no way to split these between the various converters (Eggenfellner, Stratus, NSI, etc.).

9387 aircraft are merely listed as "AMA/EXPR" in the engine slot. Of the planes definitively listed as Experimental/Amateur-Built, 4,568 have the engine listed as "AMA/EXPR". 41,277 aircraft have no engine entry at all, but only 2,000 are gliders.

Turning to the accidents, my 1998-2006 database shows 275 accidents involving auto engines. Ninety-eight involved what the NTSB identified as Subaru engines. They were split evenly between fixed-wing and rotary-wing aircraft. Five of the aircraft were RVs. Of those five, only one involved an outright engine failure. Another was an engine failure due to undetermined causes, one was due to a fuel system problem outside the firewall, and the other two were pilot error.

About 30% of the Subaru-engined homebuilts crashed due to engine problems. About a third of the engine-related cases were due to the ignition system, about 20% stemmed from internal problems with the engine.

Ron Wanttaja

 

[tonycondon]

considering that the liquid cooled engine on the P51 was designed to be flown in an aircraft, and not driven in a car, it did (and should've) performed well in that application

 

[Hiperbiper]

considering that the liquid cooled engine on the P51 was designed to be flown in an aircraft, and not driven in a car, it did (and should've) performed well in that application

It didn't do too bad in the Unlimited boat racing of the 70's and 80's...

'course it was runnin' in water at the time and got to coast to a stop...

Eddie Hill blew so many -9's in his boat he got nick-named "Merlin" for a couple of years...

Chris

 

[Dave Krall CFII]

Dave; you are right in one way, the P-51 was the most formidable liquid cooled ride in the entire WWII (which is not to dis the British Tifffe with it's 24 cylinder liquid cooled noise maker). However; it's losses during the latter 1944 and the first of 1945 marked is as inferior to the radial engined -47's and British Beaufighters during ground attack (the most common duty at the time) due to it's need for a cooling system. One bullet in the radiator or the piping that ran thruout the BELLY of the -51 brought you down. Soon. And in the Enemy camp.
My dad was shot down strafing a German 'drome in Febuary of 1945 in a P-51B. He always said if he hadda' been in the 'bottle (the slang term for the P-47) he would have gotten back...and he absolutly HATED the P-47...*

In our world, if air will cool the cylinders to the required temps then the liquid cooling system does exatcly...what?
The Spit, Hurri, Tiffi, Mustang, 'Cobra NEEDED cooling that could only be offered by liquid cooling systems due to designed form drag requirments.

I myself love innovation. To replace something with something that's different, not better, well; that is just being different. Not Innovative.

Just my Rambling thoughts.

* Kendall E. Carlson 336 FS 4th Fighter Group
Chris

I'm certain the Mustang's non-combat crash record is much better than while being shot at. For now, I am betting my slant 4 turbo's (Garret) liquid cooled plumbing won't get shot out while I'm airborne in it but who knows? I think I'll still arm the aircraft well to help prevent that...

The engine I'm using requires liquid cooling to get the sustainable high HP/weight, it's not just to be different. However it can easily run without coolant at REDUCED power long enough to safely facilitate an emergency landing.

 

[GigG601XL]

The Corvair, derated to 100 HP, seems to be gaining popularity in the Zenith homebuilt community. There are more than a few 601s flying with them. Even so, there are many fewer of those than there are Rotax or Jabiru or O-200s.

26 flying in 601s. Hopefully #27 or 28 is in my hanger.

Don't forget all the KRs out there with Corvairs in them as well.

 

[gismo]

It is a lot of the reason. The problem is getting rid of the excess heat at high power loadings. As has been pointed out elsewhere, the typical auto engine is loafing along at highway speeds, whereas the GA engine is 65% - 75% power at cruise.

This doesn't mean that auto engines cannot be designed to do this. International Harvester, a truck/industrial equipment manufacturer, used to (don't know if they still do) test 100% of their engines for 200 hours at full rated power, then pull them apart for signs of burnt valves, etc. Of course these truck engines were significantly larger and heavier per hp to handle the loads and heat. And they developed the high power at high rpms. In aviation uses, that would require gearing to slow the prop, or much shorter multiblade props.

All in all, a purpose-built engine like the Lyconentals is an excellent compromise, better than anyone has been able to certify from an auto conversion. Don't let this stop you, though. Grab an auto engine, modify it as required, and get it certified!

-Skip

A significant number of automobile engines have been converted to marine applications where they run at 75% power for extended periods and they will generally run 2000 hours without much in the way of maintenance beyond oil changes. There are many reasons why auto engine designs aren't well suited to aircraft use but their inability to run at high power continuously isn't one of them.

 

[Ted]

At different times I owned 2 V-12 XK-E's. One a convertible and one coupe.
All I can say is there was a reason why, shortly after it was imported into the US in the '60's there was a conversion kit for the Chevy 350! The Jag V12 was a POS!

Yeah, the reason was that Americans don't know how to work on cars that have more than 8 cylinders and something other than a Holley 4-bbl carb. As one of the good Jag V12 mechanics, I would definitely say it is not a POS, but you do need to know how to work on it (reminds me a lot of airplanes). The first one I had I bought at 130,000 miles and only took off the road at 170,000 miles because after 40,000 miles of me using the gas pedal as an on/off switch and not shifting below redline on a regular basis, the rings weren't happy with me. The present one is a baby, only 67,000 miles, and runs great. I'd jump in it today and drive it to California without hesitation.

 

[Ted]

considering that the liquid cooled engine on the P51 was designed to be flown in an aircraft, and not driven in a car, it did (and should've) performed well in that application

+1 .

 

[Skip Miller]

A significant number of automobile engines have been converted to marine applications where they run at 75% power for extended periods and they will generally run 2000 hours without much in the way of maintenance beyond oil changes. There are many reasons why auto engine designs aren't well suited to aircraft use but their inability to run at high power continuously isn't one of them.

Lance, I admit I haven't been involved with an automotive conversion to marine use in a few decades, but back then one of the big items on the conversion was to install exhaust valve rotators to keep the valves from heating unevenly and burning. So I guess we are talking about what the conversions today entail. I am sure it is more than ripping off the radiator and fan, and installing a raw water heat exchanger.

-Skip

 

[Hiperbiper]

Yeah, the reason was that Americans don't know how to work on cars that have more than 8 cylinders and something other than a Holley 4-bbl carb. As one of the good Jag V12 mechanics, I would definitely say it is not a POS, but you do need to know how to work on it (reminds me a lot of airplanes). The first one I had I bought at 130,000 miles and only took off the road at 170,000 miles because after 40,000 miles of me using the gas pedal as an on/off switch and not shifting below redline on a regular basis, the rings weren't happy with me. The present one is a baby, only 67,000 miles, and runs great. I'd jump in it today and drive it to California without hesitation.

If you're serious about driving a Jag V-12 from PA to CA you'd better bring along a good mechanic!



Oh wait...you ARE a good mechanic!:smile: Confidence should be high...


Just pullin' your chain Ted.

I even have a friend who likes/owns a gaggle of TR-3-TR4's...I personally think he's a glutton for punishment but he loves 'em ...

Chris

 

[Cedhed]

A note about automotive engines is their current popularity in airboats, which feature similar usage patterns to our current aircraft motors.

In fact yesteryear the most popular airboat motor was an old Lycoming/Conti. but due to the expense and difficulty of maintenance, they have been replaced with auto engines, the Chevy 350 being the most popular. And from everyone I've talked to they hold together very well in that usage pattern.

The biggest problem with auto conversions is their experimental nature. Sure there are some prefab solutions and they work very well. But most are old engines grabbed out of a junkyard and haphazardly mated to the reduction drive and fuel system. That's just bound to be unreliable. For every well designed Eggenfelter solution there are 3-4 junkyard specials with varying quality of engineering behind them.

That said there is nothing inherent in auto conversions that makes them less reliable if done properly. Cooling is easy to tackle with a little engineering. the ignition can be easily made dual, I've even seen a backup magneto added. And reduction drives have been used very successfully before (P-51 anyone? Yeah the Merlin had a redrive)

And honestly if gas spikes above $6 a gallon again the big Lyco/Conti solution is going to start looking worse and worse while those 4gph VWs and 5.5gph Subarus are going to start looking better and better. Not to mention the competition from Jabiru and Rotax.

 

[jmaynard]

And honestly if gas spikes above $6 a gallon again the big Lyco/Conti solution is going to start looking worse and worse while those 4gph VWs and 5.5gph Subarus are going to start looking better and better. Not to mention the competition from Jabiru and Rotax.

Yeah, my O-200 burns about a gallon an hour more than a Rotax. I decided that that $4-6/hour was worth it for the peace of mind I got from knowing any A&P out there can work on the thing.

 

[Dave Krall CFII]

Yeah, my O-200 burns about a gallon an hour more than a Rotax. I decided that that $4-6/hour was worth it for the peace of mind I got from knowing any A&P out there can work on the thing.

Does/has anyone ever successfully turbochanged an 0-200 or some traditional aircraft engine only slightly bigger than that?

 

[Trapper John]

Does/has anyone ever successfully turbochanged an 0-200 or some traditional aircraft engine only slightly bigger than that?

Smallest one I've seen is the turboed 0-320 on the Twin Comanche.


Trapper John

 

[jmaynard]

Does/has anyone ever successfully turbochanged an 0-200 or some traditional aircraft engine only slightly bigger than that?

Good question. Wouldn't you have to start with a fuel-injected engine, though? At least I don't remember seeing any carbureted, turbo/supercharged aircraft engines...but now that I think about it, what's the Rotax 914?

 

[GigG601XL]

...but now that I think about it, what's the Rotax 914?

A Turbo 912

 

[jmaynard]

A Turbo 912

Well, I knew that much...but is it carbureted or injected? Any other turbocharged, carbureted aircraft engines out there?

 

[Dan Thomas]

Well, I knew that much...but is it carbureted or injected? Any other turbocharged, carbureted aircraft engines out there?

Yup. The TR182 (T182RG to some folks) has a turbocharged carbureted engine. And many of the old WWII fighters were either turboed or supercharged and still carbed. The turbo forces air into the carb, while superchargers usually compress the air/fuel mix downstream of the carb.

Dan

 

[GigG601XL]

Well, I knew that much...but is it carbureted or injected? Any other turbocharged, carbureted aircraft engines out there?

That's what I meant it is really just a Turbo 912. Carbs and all. It has 2 Bing carburetors just like the 912.

 

[Dave Krall CFII]

That's what I meant it is really just a Turbo 912. Carbs and all. It has 2 Bing carburetors just like the 912.

The above answers point to an additional reason to go auto conversion, if one wants turbo charging power at altitude on the smaller displacement engines like 200 cubes or less. I've not been able to find anything.

Too young for me to call the Turbo Rotaxes traditional aircraft engines, they have more than their share of problems too.

 

[GigG601XL]

I wouldn't call them traditional but they are certified now. Or there are at least certified versions of both the 912 and 914.

 

[Henning]

I state right off the bat that I know almost nothing about the conversion procedures that would have to take place, but most approved engines are finicky at best. Ever try Hot starts with Conti & Lyc? Weight would be one consideration, but VW, corvair & Porsche are all finicky too.

I know for the majority you would have to have liquid cooling, but say a smooth running Lexus V8 that never breaks down, and can go forever it seems. I don't know if the computer can calibrate appropriately for higher altitudes?

I have seen where they used a corvette engine in a copy of a P51.

How hard, & why not in an experimental?

Funny you should bring up the Lexus V8 because that is the exact engine Toyota had hanging on the wing of a Revlon Red Aztec they were testing at LGB. They gave the program up because they could achieve neither the reliability nor the efficiency of the Lyc IO 540 on the other wing. This is the story I got from the engineers on the project. They were right across the way and I followed it with keen interest. These engines "go forever" in cars because cars rarely ever see 65% power while planes rarely see below it.

As for hot starts, I never have a problem hot starting engines. Just understand what is going on and purge the injector lines with fresh fuel before you crank and all is well.

 

[Henning]

O.K., but you have to figure out where to put the radiators, water pumps, and all the other stuff every time you use a car engine. And plenty of Mustangs came down because their radiators got shot out.

Sure, if there were no FAA and 15K airplanes/company/year coming out, there probably would be some super liquid cooled system on airplanes. Theilert started out as a Mercedes engine, if I recall correctly. Heck, there's a liquid cooled engine on my sportbike and the bike is lighter than my last air-cooled one. But airplanes are only produced at a trickle, and we're stuck with engines from the stone age being the best thing available.

Continental used to make a TSIOL liquid cooled engine that was put in a lot of 414s on a RAM conversion, I haven't seen one in a decade.

 

[Henning]

Well, I knew that much...but is it carbureted or injected? Any other turbocharged, carbureted aircraft engines out there?

My Travel Air had 2 turboed carbed O-360 Lycs on it. I've turboed many carbed auto type engines. There's two ways to do it, either mount the carb on the turbo inlet, or build a sealed box around the carb and blow through it (less turbo lag with this method).

 

[Trapper John]

Continental used to make a TSIOL liquid cooled engine that was put in a lot of 414s on a RAM conversion, I haven't seen one in a decade.

Was that the Tiara?


Trapper John

 

[tonycondon]

Continental used to make a TSIOL liquid cooled engine that was put in a lot of 414s on a RAM conversion, I haven't seen one in a decade.

i saw one one in SE missouri, I think it was owned by a high end club in the chicago area. Guy said that its kinda nice but that RAM doesnt support them anymore and the mechanics are constantly chasing coolant leaks.

 

[Dan Thomas]

Was that the Tiara?


Trapper John

It was the Voyager engine, named after the nonstop around-the-world airplane built by Rutan, which had two of them in it. The Tiara was aircooled.

Dan

 

[Henning]

A significant number of automobile engines have been converted to marine applications where they run at 75% power for extended periods and they will generally run 2000 hours without much in the way of maintenance beyond oil changes. There are many reasons why auto engine designs aren't well suited to aircraft use but their inability to run at high power continuously isn't one of them.

Much heavier engines. By the time you get a SB Chevy down to flying weight and ready to sustain 75%+hp and put a redrive on it, you've got more $$$ in it than a TSIO-550. (OTOH, for the same parts money as 350hp, I can have 600+hp as well.) But it still wont have the BSFC of the TSIO 550. I'd like to play with the new big aluminum Mopar Hemi though... I think I could make that work out quite well.

 

[Henning]

i saw one one in SE missouri, I think it was owned by a high end club in the chicago area. Guy said that its kinda nice but that RAM doesnt support them anymore and the mechanics are constantly chasing coolant leaks.

I don't think anyone supports them anymore.

 

[Ted]

If you're serious about driving a Jag V-12 from PA to CA you'd better bring along a good mechanic!

Oh wait...you ARE a good mechanic!:smile: Confidence should be high...

Let's see, in the past year I've done zero necessary maintenance on the Jag, just preventative (fluids) and changed out the shocks for some higher performance ones, and put 10,000 miles on the car.

By comparison, my Ford broke its exhaust studs (I've NEVER had a Jag with an exhaust leak at the manifolds) and so I had to pull the manifolds off, drill out and re-tap the broken studs, and put some new headers on. Shocks were completely dead, so they needed to be replaced. I've got a few other projects I'm saving on it for next spring. I put about 16,000 miles on it in that time period... and it's only 8 years old. My first Chevy threw a rod at 173,000 miles, I could go on and on.

Yep... clearly Jags are unreliable POS cars.

Just pullin' your chain Ted.

I even have a friend who likes/owns a gaggle of TR-3-TR4's...I personally think he's a glutton for punishment but he loves 'em ...

I know, but after hearing this for the past 8 years, I've found people who think this way are either uneducated or are just propagating myths they heard from others who were uneducated. When the XJS gets retired (I'm anticipating to retire it around 200,000 total miles) I'm likely to go out and buy a '00-'03 XJR to replace it. Maybe by that point someone will have made a kit for swapping out the Mercedes 5-speed auto with a manual (I hate automatic transmissions).

Funny you should bring up the Lexus V8 because that is the exact engine Toyota had hanging on the wing of a Revlon Red Aztec they were testing at LGB. They gave the program up because they could achieve neither the reliability nor the efficiency of the Lyc IO 540 on the other wing. This is the story I got from the engineers on the project. They were right across the way and I followed it with keen interest. These engines "go forever" in cars because cars rarely ever see 65% power while planes rarely see below it.

Yep... and it's amazing how many pilots don't seem to understand the difference here. I can understand non-pilots not getting it, because they really don't understand it how aircraft engines are run. The other thing is that aircraft engines are very good at seeming like the power they put out is effortless, by being relatively quiet and smooth at those power output levels. My Dodge was good at the same, I'd run it at 65-75% power routinely while towing for extended periods of time. I even ran it at 100% power for about 20 minutes straight with an enclosed trailer attached (tornado avoidance). It was also a Cummins turbo diesel, not a Hemi.

As for hot starts, I never have a problem hot starting engines. Just understand what is going on and purge the injector lines with fresh fuel before you crank and all is well.

I've not had any hot-start issues on any of the planes I fly, including the IO-360 in the Mooney. Goes back to a lack of education. People seem to think they shouldn't have to learn anything about engine operations, and just be able to get in and go. That same mentality I suspect is what causes the high rate of crashes in "hot" aircraft because they don't learn how to properly handle the things before going into a challenging situation, and that's how you get a bent plane.

 

[Dan Thomas]

A significant number of automobile engines have been converted to marine applications where they run at 75% power for extended periods and they will generally run 2000 hours without much in the way of maintenance beyond oil changes. There are many reasons why auto engine designs aren't well suited to aircraft use but their inability to run at high power continuously isn't one of them.

I put a Chev 283 in a boat years ago. I could run it at full throttle near redline RPM without the temperature gauge even coming off the cold peg if I had the water valve wide open. (No thermostats on raw-water cooling systems because bits of weeds will plug them). The only limiting factor was the mechanical fuel pump; it couldn't pump enough fuel at full power and would start falling behind as the carb bowl began to run dry and the engine would hesitate and RPM dropped off. Fuel consumption at anything near full power was awesome; I was getting about one mile per gallon at about 45 mph. Even at 30 mph cruise I didn't get any better than 2 mpg.

A couple of lessons from the above:

1. Thermal efficiency suffers as RPM rises. There's too little time for full-power fuel flows to burn properly at 4200 RPM and the wastage is terrible. Lots of flame coming out of those exhaust valves, which is hard on them. (The exhaust systems on inboards are water-cooled because there's no airflow around them, but even so they can get plenty hot.) Any auto conversion needs to run at those high RPMs to get rated power, and will have to deal with thermal efficiency losses. The aircraft engine, operating at much lower RPMs, has more time to allow the fuel to contribute to the power output.

2. Cooling a boat engine is a no-brainer. Common are raw-water systems like I had, where the pump sucks water from a small inlet under the boat, passes it through a gate valve to control flow, shoves it through the transmission's oil cooler, then splits the flow and runs half through each exhaust manifold jacket, brings the flow back together and runs it into the block inlet (where the old water pump used to be), out the top outlet (where the thermostat used to be), splits it again and runs it into the exhaust pipes at the rear of the manifolds, where it mixes with and cools the exhaust gases and is ejected with them. All the hoses on the 283 were 3/4" heater hoses. The water is stone-cold and there's so much of it and the little positive-displacement pump makes sure it's moving so there are no overheating problems, ever. Saltwater cooling systems, since salt is bad for metals, often use a heat exchanger on the bottom of the hull, a marine version of a radiator, but again there's lots of dense medium to absorb heat.

The aircraft engine has to deal with weight, areas and locations of radiators and the like, airflow through those radiators (faster air doesn't always translate into more cooling), and no such handy thing as raw-water cooling. The heat has to be dissipated into the air just the same as the air-cooled engine, but the liquid-cooled engine does it in a much more complex and heavier way. It's only advantage is the controllability of engine temperature, which might allow for more power output per cubic inch.

Dan

 

[gismo]

Much heavier engines. By the time you get a SB Chevy down to flying weight and ready to sustain 75%+hp and put a redrive on it, you've got more $$$ in it than a TSIO-550

That would be some of the "many reasons why auto engine designs aren't well suited to aircraft use" I mentioned.

 

[Henning]

That would be some of the "many reasons why auto engine designs aren't well suited to aircraft use" I mentioned.

There is the counterpoint though, and that is for the same money as it would take to get it to compete with the 310hp 550, I can make it have 450-600hp. I tried working with the FAA to let me hang a V-8 Chevy on my Ag Cat, but they wouldn't go for it unless I bought an Orenda.

 

[Jim in NC]

Not even close. I just walked downstairs and asked for the dyno setting at 50 mph - 17.5 hp for a F150 diesel (this is at the rear wheels) - figure less than 20 hp at teh crank which is about .07 hp/in cubed. For an O-360 (at the same hp/ cu in), this would be a grand total of 24 hp - I think you typical O-360 will put out more than 24/0.7 = 32 max horsepower.

Yep, you get the prize for the reduced hp at auto cruise correct. There is a big difference between maximum RPM with a partialy open throttle, and a wide open throttle at maximum RPM's.

Problem is, that has little to do with why auto engines are not widely used, or considered unsuitable by many people.

As Ron Want-a-jaw said, <g> few internal parts, or parts of the basic auto engine are causing failures in airplanes. It is all the stuff that has to be added, such as home-baked ignitions, electrical systems, fuel supply/inductions, cooling systems, and redrives, which of course can cause the crank or bearings to fail if not correctly implimented. It also would be interesting to see what the reliability factor was for the auto engines once they got sorted out, past say 200 hours. Ron, you want to get on that new study, right away, please? <g>

I'll bet that they are more reliable than certified engines, after that. Most never get that far, because most do not build on the experiences of others, and the owners get tired of fixing instead of flying, or scare themselves.

Take for example, a very popular V-6 engine in homebuilts, the Chevy 4.3 L, or you could as easily say the Ford V-6. (3.8L, I think)

That same engine is taken from the casting line, machined, has stock auto cranks and pistons, valves and all the rest put into it, and sold to a company such as Merc-Cruiser as a boat engine. Different cooling pumps, ignitions and inductions are normally used, to do away with the computer, among other things. Still, it is the same basic package that starts its life as a so called "industrial engine" in a power boat.

If a boat engine has the right prop on it, it will be at wide open throttle, and at near redline, or at least at the maximum torque to RPM value. These engines DO spend their life at these very high HP levels, and will happily do so for hundreds if not thousands of hours. I don't know of a single airplane engine that is run as hard as 90% of these boat engines, and if it is one of my boat engines, darn right, I expect it to run at 100% of its rated HP, for an hour or more at a time, and still expect it to start reliably, and run, for many years to come. Would I run an airplane engine that hard? Not quite, but would not hesitate to ask full power for takeoffs, or very near to it. I would throttle down to 75% of the maximum HP while in cruise, but mainly for noise reduction, and fuel consumption; not for fear of blowing up. I have proven to myself that the engine is good for very extended runs at 100% power, but on the other hand, there is no sense pushing luck! ;-)

If a boat engine has the right prop on it, it will be at wide open throttle, and at near redline, or at least at the maximum torque to RPM point.

Can you do this to every auto engine out there? No. VW beetle, for one. Many of the inline 4's might have some problems. But, if it is based on one of the popular GM or Ford V-8's, (as are the GM and Ford V-6's) then you have nothing to fear from the basic engine, itself.

You had better do your homework when it comes to all of the other stuff that makes engines run, though. It's those items that pose the "gotcha."

Why did Orenda not make it? Too large a goal, I think. 600 HP out of a V-8 puts it up there near racing engine outputs. Racing engines do not live hundreds or thousands of hours. Also, the other missconception is that Orenda was a stock GM engine. It was not. It was based on one, but was its own casting, and had some other modifications done to it. Still, some people were very happy with them. It is a lot of tradition to buck, to be put on one company, to get everyone to accept an auto style engine as being equal to the accepted old style piston airplane engine.

So, is an auto engine going to come along to be the next accepted airplane engine? No, not any time soon. Is it possible to fly behind an auto engine safely? It is possible, but you have to make up your mind; are you going to tinker, engineer, study other's attempts, or you going to put something in that everyone accepts, and fly it?

Your choice. Be prepared to do your homework, and break some new ground.

Jim in NC

 

[wanttaja]

As Ron Want-a-jaw said, <g> few internal parts, or parts of the basic auto engine are causing failures in airplanes. It is all the stuff that has to be added, such as home-baked ignitions, electrical systems, fuel supply/inductions, cooling systems, and redrives, which of course can cause the crank or bearings to fail if not correctly implimented. It also would be interesting to see what the reliability factor was for the auto engines once they got sorted out, past say 200 hours. Ron, you want to get on that new study, right away, please? <g>

For you, Jim, anything....

Overall, there were 275 auto-engined homebuilt accidents in the 1998-2006 time frame. About 56 accident reports did not have an entry for the total airframe time (there is no column for total engine time). Of the ~220 accidents where an airframe hours was listed, 57 had 200 or more hours.

The engine was the primary initiator of the accident series in about the same percentage...about 15% of the accidents, in both cases, were attributed to engine internals, ignition systems/controller, redrives, oil system, carburation, and cooling systems. Both the overall auto engines and those with more than 200 hours suffered about the same rate of "undetermined" engine failures...cases where the pilot lost power, but the examination afterwards did not reveal a cause.

This means that there was only 20 instances where the engine was the cause of the accident for planes with more than 200 hours. This *does* tend to distort the results a bit. But here are the raw results. This is the percentage of total cases where the engine was the cause of the accident, not the total number of accidents:

Engine internal failures: 17% overall, 10% (only two, remember!) for >200 hours.

Fuel Problems (engine side of firewall): 2.3% overall, 5% >200 hours (one instance)

Ignition Problems (including controllers): 17.4% overall, 15% >200 hours.

Redrives: 4.8% overall, 15% >200 hours

Carb problems: 3.5% overall vs. 10% >200 hours.

Cooling systems: 4.7% overall vs. 5% >200 hours.

Again, since there are only 20 accidents for auto-engine homebuilts with more than 200 hours that were attributed to the engine, it's kind of tough to draw conclusions. Each accident is worth 5% of the total. But it is interesting that the cooling systems score about the same, but the reduction drives have a three-times higher rate for the higher-time auto engines. Again, though, we're only talking three accidents out of the 20...

Ron Wanttaja