Auto engines for homebuilt aircraft

[seattle smitty]

New to this website (howdy, howdy) . . .

I can see where this might be a good place to get some educated input about auto engine conversions for light aircraft. The flying do-it-yourselfers have such columns, but while they come up with good tips on aircraft structures, coverings, instrumentation, and so on, there seems not to be a lot of community experience with engine rebuilding and modification. Part of this may come from the fact that the A&P certified mechanics who would normally be the main resource for aero-mechanical knowledge actually are quite UNlikely to know about any part or proceedure that is not FAA certified. An airline mechanic is NOT employed to exercise his imagination and creativity; such thinking is adamantly dicouraged with threats of legal liablility! Therefore, the homebuilders, who ARE allowed to experiment, are left to consult each other, but they don't seem to have much background. It seems to be just in the last decade, for instance, that they have discovered the possibilities of tuned exhaust systems. Yet the English researcher Philip H. Smith wrote the first edition of The Scientific Design of Intake and Exhaust Systems over fifty years ago, which became the bible for ground- and water-based racers from then on.

For another example of where the aviators are at, there's a book on auto-engine power for planes by their welding expert, who also raced cars a little bit. I borrowed a copy from the library and took it over to my buddy who owns an auto machine shop, and we read passages and laughed our heads off. Our favorite bit of "expert" advise: when deciding between auto engines you might want in your airplane, go to the car dealerships and get test-drives in vehicles with the engines under consideration, and see which you like best. The plane people plainly need help.

One of the car engines favorably mentioned for many, many years in the aircraft homebuilders' magazines, with conversion parts offered commercially, is Ford's old 90-degree V-6. This should raise eyebrows among the ranks of auto machinists, who know the Ford V-6 to be among the most notorious cylinder-head-crackers from the era of cracking heads. But I have never seen a reference to this by any of the aero magazines engine experts. (Now to be fair, automotive writers can be remiss about this subject. i've seen dozens of hop-up articles on the Mopar 360 small-block without anyone admitting that you can hardly find an uncracked pair of 360 heads after a day in the wrecking yards).

That said, there are some cool projects to be seen. One of the guys who checked in at Ford Six Performance: The Web's Leading Resource for Ford Inline Six-Cylinder Engines and Cars! is building a full-size replica of a WW1 Fokker D-VIII, possibly the hottest fighter of that war, and was getting info on the Ford 300-six engine. It might be a good pick for him, since it can be built to be very stout, very torquey, AND, since there will soon be an aluminum head available to cut some weight.

Ryan Falconer is a name that might be known to older hot-rodders here, since he was one of the most imaginative engine-builders in the old days. He is now manufacturing an all-aluminum 60-degree V-12 aero engine of his own design, with several examples flying and being raced at Reno and elsewhere.

The old all-aluminum 215 Buick and Olds engines of the early '60s have a small following among the homebuilders, who generate new articles saying the same old things about it every few years. I had been interested as well, and knew of the work of Seattle machinist Phil Baker who made these engines, bored and stroked to as much as 305 cu. in., a specialty. But the aviators never picked up on Baker, oddly, since a long-stroke, small-port, slow-turning torque-motor is just what an airplane wants. Even stranger, I have never seen the "experts" talk about all of the improvements made to the aluminum Buick engine after it was taken over by Rover in England. Almost every change Rover made to that engine made it stronger and safer for aircraft use . . . but the aero magazines are still talking Buick!

Is anyone else here interested in the subject of auto engines for small planes?

[Dusty]

yeah there are a few subaru conversions in rvs as well as rotary engines. Imagine a harmon rocket with a v8 or turbo six

[Pinhead]

Originally Posted by Dusty

yeah there are a few subaru conversions in rvs as well as rotary engines. Imagine a harmon rocket with a v8 or turbo six

I have a friend back home that uses the Subaru flat-4 in his homemade ultralight helicopters. I don't know exactly what he does to the engine, though, to make it more suitable for use in the air. It does have the advantage of being extremely light for the power and torque it produces, as well as having extremely long intake runners to help tune it for toruqe.

[seattle smitty]

I saw a Harmon Rocket with, I think, an IO-540, anyway a gigantic engine, at the Arlington, WA EAA meet this summer. I think it could probably hang on its prop like a helicopter! But an auto engine conversion would be even wilder. There was an article in one of the magazines a few years back of someone who had built an aluminum Buick for his BD-4, and made it a taildragger. Very neat machine!

[BMac]

Originally Posted by Pinhead

I have a friend back home that uses the Subaru flat-4 in his homemade ultralight helicopters. I don't know exactly what he does to the engine, though, to make it more suitable for use in the air.

It doesn't need anything to be suitable for aircraft. Made by Fiji Heavy Industries when they first started building those engines for aircraft.
I rebuilt my EA71 1600cc 65hp engine and you wouldn't believe how it's built. You can't even feel the weight of the pushrod in your hand!

[don2]

I like the idea of using an ls series motor.

Firewall Fwrd

[mlilja]

Hi,

My name is Mike and I am quite new to this site as well. After reading much of the other technical things I looked around to see what else was here and found this forum. To give you a little background. I am a licensed A&P who got into it because of my interest in gaining some real life experience before building a homebuilt aircraft. I have done extensive reading research and had many discussions on the pro's and con's of using various power plants for aircraft. For homebuilts you have so many options even when using a standard aero engine, you may want to consider that course. Get a couple of copies of Kitplanes, read the articles and take a look at the adds. The possibilities become almost endless. There are a couple of diesel options as well and I think that may be the best option for aircraft.

The first thing to consider is what type of aircraft you are going to build. Many ultralights use one form of Rotax or another. RV's have probably the most options available, from uncertified standard aero engines to Rotary to Subaru and other similar engines. Keep in mind for the home builder you can buy many uncertified aero parts for a whole lot less money just because they don't say FAA/PMA approved. They are the same parts with no certification. Precision Airmotive's fuel injection (Bendix style) comes to mind immediately.

As far as using an automotive conversion, the conversations have always revolved around reliability. Aircraft engines were designed at the outset to run 65-75% power all the time. Where as an auto engine doesn't often see much above 50% and most of the time is down around 20%. So, no matter what auto engine you use, there better be available better than stock parts.

The second is engine speed. The highest RPM direct drive aircraft engine I am aware of is the Lycoming TIO-541 which turns at 2900 RPM and most engines usually no more than 2700. All auto engines that have been considered need much more RPM than that to make enough power. Which means you will need to incorporate a Propeller Speed Reduction Unit (PSRU) to get your prop speed down and your torque at the prop up. Also, the engine power is output at the low (physical dimension) end of the motor and you need some way to get the prop shaft at some level that will work with the cowl and aircraft design. A PRSU usually accomplishes this task as well. But a PRSU means more weight and more things to go wrong.

The next big thing is cooling. Since most of the conversions considered are liquid cooled you need to work out a way to mount a radiator. The other problem is at the power outputs necessary, can you mount a big enough radiator for the additional heat rejection of the engine through the cooling system. This is where I think coatings could be a big help.

There is my two cents worth to start with. Hope this helps with your research and the discussions.

Mike

[DavidHarsay]

Hello,

I'm a licensed A&P, but I cannot help you, because I have no imagination beyond what the FAA allows me to think... even though I spent over 8 years building my own auto-powered aircraft.

[seattle smitty]

What I MEANT, and expressed without the necessary disclaimers and caveats, was that the FAA (also P&W, GE, Rolls, Lycoming, Continental, and the rest) do not want you to get creative with their approved engines in approved aircraft, and that any specific knowledge and experience of non-certified engines and aircraft an individual A&P mechanic acquires will have to come from outside of his work and his training for work. I didn't think I implied a lack of ability to be creative among A&Ps, many of whom I know and respect, many of whom do very interesting projects outside of their workplaces. I should have expected that someone will always make the unintended inference. I should have been a lawyer so I'd remember to cover myself against every possibility of offending anyone.

[DavidVizard-GFN]

Here is an example of the dated design of main stream private sector aero engines. About 1997 ish I got involved with Magnum Engines on an upgrade of an IO 540. When I checked the cam on my computerized checker I could hardly believe that this was what they were using for however many years the engine has been in existance. Remember we have an engine that is supposed to turn no more than 2700 rpm. Why in the world do they install a cam that is about 300 degrees duration at lash. Also the dynamics were dreadfull. I can tell you with absolute certainty I can file a better cam than that. Any way we had Harvey designs some new profiles that were about 30 degees shorter and with top notch dynamics. I can't remember for sure but it think the end result was abolut a 20 hp at 2500 rpm (about 40 lbs-ft). Along with this the fuel consumption was less! A check with Magnum Engines (in Ontario Ca. last time I heared from them) will get you aero buffs all the details you need.

As for auto powered kit planes Bruce Crower built, I believe, an RV4 with a 430 inch all aluminum SB Chevy in it. I heard it had about 375 horses but, if you need a number for sure I'll bet the guys at Crower will tell all.

DV