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Automobile engines used in aircraft

O

OBIO

Retired SOH Admin
I know the Pietenpol Air Camper used a Ford Model A engine way back in the day, and that that was a successful pairing.

I was just on Youtube and came across some videos of various planes powered by modern GM LS1 V-8 engines. Reading through the comments from the builders of the planes, this appears to be a really good way to go. The engines are cheaper, more reliable, more efficient, cheaper to maintain, and produce more power. The LS1 design, which is pretty compact for a 5.7 litre (roughly 350 cubic inches) engine, fit easily into a C172, a RAV10 and a Raven. Climb out seemed to gain the most from this engine usage...as Vne is dictated by the airframe far more than the engine and available horsepower.

This leads me to some questions, and hopefully someone on here may have a bit more info and can answer them.

1) How often would these engines need to be torn down and rebuilt? I know that a modern car engine can clock 100 thousand plus miles with ease, but how do FAA regulations come into play in terms of engine rebuild times?

2) Would these engines still be run on regular gasoline (most likely high octane) or would they need to run AV-Gas?

OBIO
 
As far as I know they run on normal gasoline, at least some of them do. There are several RV-8's using V8 and V6's out there. In fact there are many Vans' planes with automotive engines.

I'm not sure how FAA regulations affect homebuilt aircraft. I'm sure someone else around here can answer that. Robert perhaps...
 
As far as I know, every WW1 aircraft was flown using automobile engines ... In the case of military use, I'm sure they got torn down and refurbished as soon as the mission was over and the pilots got back to base.
 
Been doing some comparisons between aircraft engines and the Corvette LS1 (which is the one used in the aircraft I saw videos of since the Vette LS1 is an aluminum block based engine).

Lycoming 0-360 In-Line 4 (Cessna 172)

Weight: 280 to 300 pounds
Power: 180 horse power
Fuel Consumption: 10 US gallons per hour at 65% power, 10.5 US gallons at 75% power

Corvette LS1

Weight: 400 to 430 pounds
Power: 350 to 400 horse power\
Fuel Consumption: No idea...but it surely has to be better than 10 US gallons per hour. Even if it is 7 US gallons per hour, that alone is a substantial fuel efficiency improvement.
 
Chevy V-8's are the big thing and have been for perhaps 20+ years. Witman was using them in his little Homebuilts.

On most planes, you have a hour meter, and at a recommended point, its time to have the engine looked at, as I am sure you know, but I have no idea what the hours would be on a regular V-8. I am sure that most will have certain time zones to require a tairdown.

The main difference though on a aero engine and a car engine, that I found out, is that an aero engine is designed to cruise at flat RPM ranges, like say running at a constant 2500 RPM or 3000 RPM, etc. Peaking is only at say take-off and some climb-outs. With automobile engines, you have constant up and down RPM ranges, constantly.... They are designed for that. In having said that, I would 'think' that auto engines would then be ideal for aero use, so long as they are a reliable engine. (Some are terrible and you dont want a break down in the sky). So you want to pick the best around that will never break down.


Side note. I always thought that the newer Land Rover V-8 was ideal for an aero engine. Its fuel injected, all aluminum block, aluminum heads, super light weight, high torque, fuel injected with a superb fuel injection system. Bad side, its water cooled and you dont want to overheat the heads as they can warp. They had a issue with getting bubbles in the block and heads, and you needed to get those out to have it cool properly. The engine is no longer in production however. Some say that it wouldnt be a good choice as it uses a Lucas control ECU management system, (brain box), but having worked for them and did testing on them, I learned that Lucas was assigned to build 'exactly' what LR needed or they would go elsewhere. Thus LR would create the programs, chips, board designs, and then Lucas simply manufactured them. They had to be 'highest quality'. For many years, Range Rover had the second highest ratings to the public, from reliability to quality, second only to Acura, which both held those ratings for perhaps 4+ years. Thats a really high rating.

Later, when LR was sold, first to BMW, then a semi-take-over by ford, (BMW wanted to keep LR but ford pulled some strings), the engines were switched to BMW V-8's, which are extremely high quality, but high cost. The LR engines had lost their quality ratings as QC had gone down hill during the BMW/Ford times. Now its in the hands of India, so who knows where its at now. But, back in the day.... that was a good engine. That would have been an excellent aero engine.....

Colin Chapman was into aircraft also. He was having an aircraft design made when he left this world. I am sure he had ideas for an aero engine or two.

I always had my mind on Wankles. Rotary engines have low vibration, are rather like a turbine, have great torque, and a phenomenal torque range, from like 3,000 to 7,000 RPM, depending on model type. Bad rotor seals for years ruined their high end quality ratings, (they needed a rebuild after like 60,000 miles due to seal wear). Now the engines have new seal technologies but the past looms over them. Bad things about them; water cooled, run at higher RPM's, sound levels are higher, sounding a bit like a two stroke if you dont have good muffler systems on them. Fuel ratings arent good either. They love gas...


Bill
 
OBIO said:
Been doing some comparisons between aircraft engines and the Corvette LS1 (which is the one used in the aircraft I saw videos of since the Vette LS1 is an aluminum block based engine).

Lycoming 0-360 In-Line 4 (Cessna 172)

Weight: 280 to 300 pounds
Power: 180 horse power
Fuel Consumption: 10 US gallons per hour at 65% power, 10.5 US gallons at 75% power

Corvette LS1

Weight: 400 to 430 pounds
Power: 350 to 400 horse power
Fuel Consumption: No idea...but it surely has to be better than 10 US gallons per hour. Even if it is 7 US gallons per hour, that alone is a substantial fuel efficiency improvement.
Click to expand...

There's your big difference. Aircraft engines spend a lot more time "pedal to the metal" than automobile engines do; so, to make them more reliable; they are often derated to a lower horsepower. I think they are usually set to run richer as well; since it results in a cooler running engine.

Less power, sure; but also less chances of it failing when you need it most. The above is especially true for helicopter engines; where an engine failure results in more drastic action.

-James
 
The LS1 is a very reliable, solid engine. And from what I read, the engine is underused in the aircraft that use the LS1. The comments in one video (made by the owner/builder of the plane) stated that take off RPMs are in the 4000 to 4300 range, cruise is 3000 to 3300 rpm. Both of these are well below the 6200 RPM factory stated redline for the Corvette LS1. An 6-bolt main, rigid construction LS1 V-8 can cruise FOREVER at half throttle and not think a thing about it.

I'm sure that these conversions add water cooling systems to the planes, so the engines won't get overly heated...no more so than cruising down the highway.

OBIO
 
Automobile engines are designed to operate in a very narrow temperature range- maintained by the cooling system. Problem is those cooling systems are of considerable weight. Also those automobile engines are designed with 'wet sump' lubrication systems, a BIG problem if you can't keep the engine upright. Dry sump conversions also add more weight to the powerplant, and are usually belt driven(to save weight) off the crank- rubber belts don't live long in cold temps. Then add the emission controls and computers to drive the electronic injection , and a reliable generator (alternator) to power the electronics and fuel pumps. All-in-all a bit more complicated than a mechanically injected, air cooled, opposed cylinder aircraft engine.
 
Automotive engines which are used in homebuilts aircraft are more like NASCAR "Stock" cars to the stock car you own. Before an engine can safely be used in an airplane it is completely rebuilt using aircraft quality cranks, con-rods, pistons, etc. The ignition system is replaced with dual aircraft systems. generaly, the only remaining OEM part is the block and maybe heads.

The reason is reliability. When you engine conks out at 3000 ft AGL, you don't pull on to the side of the road to wait for AAA. Also, as others have alluded to, the aircraft engine is run at 70-90% full load all the time with 100% on take-off. An automobile at 60-70 mph (100 km for the rest of the world) may put 30% load on the engine.

An engine's components have to be designed for the heavy stress of 80-90% loading for hours and hours.
 
jhefner said:
There's your big difference. Aircraft engines spend a lot more time "pedal to the metal" than automobile engines do; so, to make them more reliable; they are often derated to a lower horsepower. I think they are usually set to run richer as well; since it results in a cooler running engine.

Less power, sure; but also less chances of it failing when you need it most. The above is especially true for helicopter engines; where an engine failure results in more drastic action.

-James
Click to expand...

Yup, your post and Bill's pretty much sum up what I've read about auto engines (in particular the SBCs when used in aircraft). If you plan on using it at say 90% capacity the auto V8 will have a pretty short lifespan compared to a comparable power aero engine.

Looking at what OBIO posted...
He spec'd the O-360. This is a lightweight little opposed 4-banger. 360 cubic inches from 4 big pistons for that 180HP @ 2700rpm. 300lbs or so.
A better comparison to the small block Chevy to be an alternative to would be an O-540 six-cylinder. 540 cubic inches for 300HP @ 2700rpm. 438lbs or so.
If you look at the 350 Chevy, LS1 variant you're getting that 325-350HP at something around 5000-5500rom. So this either requires a gear-reduction unit for the prop and/or a serious HP/Torque derating of the engine to keep things at a livable rpm. If you run that SBC at 5000rpm all day, it won't live very many hours. And if you derate it you're killing the power/weight ratio...still carrying that 430lbs around up front.

That's the advantage of aero engines compared to car engines. They're better compared to old vintage tractor engines or motorcycle engines. Big displacement, mild rpms, wide-power band, gobs of torque, and a longer lifespan.
Parallel this to a 650 single-cylinder bike engine (like a Suzuki Savage) compared to a 650 inline 4 (Honda CB650). The 650 single makes less power @ 30HP compared to around 50 for the 4-cylinder...but the powerband is wider and torque figures are about equal so you can pull a Savage along just as good with that 30HP as you can with the 50HP bike. Those older "thumper" engines will last forever, I believe mainly because rpms are so mild...same principle that most aero engines use.

Our new local airport manager has an RV-8. I've had a chance to visit with him a bit but not too in-depth on his homebuilt. He stuck with Lycoming power in his plane but I do know others have gone the SBC route with their kits. Would be interesting to hear what his reasons were behind his choice (and why other builders choose the SBC too).


I also remember the Porsche-powered Mooneys a few years back. They had some serious engine reliability problems due to the engine being over-used in the application. Don't see that as a factory option or probably even a DTC anymore.
 
Of course, there's always the opposite end of the automotive spectrum - the old VW 1600cc air cooled boxer. I've seen more than one homebuilt with this engine, especially in Benson Gyro's.
 
I know here in dayton a group of men built a Wright flyer B model, and it is powered with a Harley twin V motorcycle engine..
Plenty of power and light weight..
So far NO Problems from the engine, been flying it several years now..
But the motercycle engine v twin EVO will run wide open for hours with no problems..

I know held Mine wide open once for 2hrs 18 minutes, as fast as she would run..
To get home during a emerency.. Much younger and braver then LOL..
 
Just came across this video on YouTube. 4.3L GM V-6 (racing engine never used in production cars). This guy built this engine for killer power. 340 horses! Sounds amazing. Would love to drop that into a 1999 to 2004 Pontiac Grand Am GT (after converting it to rear wheel drive with a Corvette independent rear end of course).

http://www.youtube.com/watch?v=MT-0zHmcp9o&feature=related

OBIO
 
GM had a 4.3 V-6 that was used in full sized pickups starting in the 80s. It was basically a 350 V-8 with a couple of cylinders removed from the middle. Just read the remarks. That racing block is the truck 4.3 souped up.
 
robert41 said:
An interesting read. http://www.vestav8.com/FAQ.htm
Click to expand...

Yes indeed interesting
[FONT=Arial, Arial, Helvetica][SIZE=+0]The new computer is very simple (only three sensors MAP, IAT, CKS) and it is fully redundant, with dual circuits, dual sensors, and dual pickups. Because O2 sensors are not used, 100LL is very usable as well as auto gas. [/SIZE][/FONT]
Click to expand...

With only those 3 sensors it certainly doesnt have sequential injection (NO cam sensor), but if has redundant systems how is ignition handled with only a single coil pack as I only see 1 ignition wire per cylinder (it's NOT coil on plug).

Still, interesting design.
 
Willy said:
GM had a 4.3 V-6 that was used in full sized pickups starting in the 80s. It was basically a 350 V-8 with a couple of cylinders removed from the middle. Just read the remarks. That racing block is the truck 4.3 souped up.
Click to expand...
Remember the Syclone/Typhoon pair with the turbocharged 4.3!? I'd bet that would be powerful enough to run a coaxial counter rotating prop set!

BTW, it the back two jugs that were lopped off. The firing order was 143652 as opposed to the 18436572 that was standard for every GM small block V8 built up through that time.
 
You'd think that a former GMC dealer mechanic would remember those two although they were about 10 years past my time. I'd clean forgot about the 4.3 also being in S-10/Sonoma pickups and SUVs. By the time the S- series trucks came out, I'd already moved on to greener pastures.

For those that don't know about the Syclone/Typhoon http://en.wikipedia.org/wiki/GMC_Syclone

One of the remarks I remember reading about these in a car rag was "Think what GMC could do if they were allowed to play with cars"
 
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