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Help Ed Build His Plane

This week on Car Talk, we heard from Ed in Pennsylvania. (You can hear the call right here.) He's got to choose between two engines.

Big deal, right? Except that this engine is going in a plane Ed is building. From scratch. No kidding. (Who screens these calls, anyway?)

Should he go for the tried-and-true airplane engine, or save $10,000 and opt for a Subaru engine? And, is this really the right place to save a few bucks?

What would you do, if having your engine stall might mean a crash-landing in the woods of Elmira?

Let us (and Ed!) know what you'd do -- and thanks.

Tom and Ray Magliozzi
Click and Clack, the Tappet Brothers

Many Aviation catastrophes have resulted from car parts being used in airplanes. Catastrophes have also resulted from [airlines] trying to save a little bit of money. Perhaps the most famous is Alaska Flight 261.

Alaska deferred maintenance on part of the flight control system (to save money) which caused it to crash out of control in the middle of the ocean.

Ed, are you insane ?

The Subaru engineers didn’t design that engine to endure the kind of conditions that aircraft engines typically do (temps below 0, 75% continuous power, depending on air cooling only when it is 90? + outside. Oh and keep in mind even a “light” aircraft can weigh over 2000 lbs when fully loaded). Thus aircraft engines are a bit more robust, necessarily.

I’m sure the NTSB would just love to find out that you were running a car engine, as they’re digging through the wreckage.

I think the choice is obvious here. Ed needs to talk to an A&P for advice that will keep him from getting himself (and his passengers) killed.

Many homebuilts use Wankels, Subarus, Beetles, the occasional Chevy. These are heavily modified for aviation use and aren’t junkers that are yanked out of the local “Automotive Recycling Center.” Chances are if you are building a fairly popular homebuilt like a Van’s Rv7 (go to YouTube and search) you’ll see some examples. Check with your plane’s mfg website or listserv and you will get plenty of info. Good luck, and remember: “Green side down…blue side up!”

I want to go on a date with Ed, he’s the 1st guy to make me laugh for 10 years! ShanePatrice on Facebook

Click and Clack acted like Ed was some kind of nut case for even wanting to build his own plane. Believe me he is not. Thousands of safe homebuilt planes are flying the airways of this nation. Both of my next door neighbors fly what are referred to by the Federal Aviation Administration as experimental aircraft. One has built five such planes, three of his own design. Two those have used automotive engines. There is certianly nothing wrong with this sort of endeavor. Personally I prefer my 59 year old Cessna, mostly because I have no time to build my own.

As for Eds engine issue, one of the great things about the Subaru engine is the possibility of turbocharging. With a turbo, Ed can fly quite high without his engine losing power due to lack of oxygen. Personally, I think Id opt for a Subaru WRX turbo engine. Wow, what performance!

As a suggestion, Ed should join The Experimental Aircraft Association. There he will find many like minded (and perfectly sane) people who have done all this before.See

You can get a nice rebuilt Chevrolet Corvair engine for a lot less than either of the other options. There is a history of using this engine in home made planes. It is air cooled, nice and compact with horizontally opposed cylinders, 6 of them. It is also simple technology. Two simple carbs - a little hole for gas and a big hole for air! Parts are readily available.

Good luck

Jim, proud owner of a '65 Corvair convertible.

  1. I didn’t know that even experimental aircraft could use car parts and get away with it. If so, great, I’m a student of aviation; I learned something new today.

  2. Nonetheless, Ed even admits in his call that the 40 year old technology used by aircraft engine mfr’s such as Lycoming & Continental is tried, true & reliable.

I firmly believe that you get what you pay for. Chances are the extra $10k will get him a nice engine that will last him 2000+ hrs without any major issues. (Aircraft engine wear is based on time not “miles”).

The Turbo WRX engine sounds novel and exhilarating, but ultimately won’t hold up as well as an engine that was designed for the job.

Ed -

I remember back in the early days of the VW Beetle, Popular Mechanics (or was it Mechanix Illustrated?) ran an article on a homebuilt using a VW engine. It has a lot going for it if the plane is small enough to match the little engine. Simpler -> more reliable. Air cooling is about as simple as it gets, and it saves weight. The horizontally opposed engine avoids a lot of vibration and thus structural fatigue. I’ve heard that marine engines still have breaker points and distributors because they degrade rather than fail catastrophically. I don’t know whether altitude affects distributor longevity, but you’re going to be on a PM schedule anyway. Remember that reduced air pressure -> reduced arcing voltage everywhere outside the engine, which means ignition components that are fine at sea level could start arcing at altitude. Engines designed for aircraft generally have dual ignition systems, but with an automotive engine you don’t have that option. I’d look up air dielectric strength vs altitude and devise a means of testing at above-normal voltage to catch anything that might arc at reduced pressure. Maybe there’s already a procedure and tools for that.

None of this addresses your choices directly, it’s just musing on general principles.

I listened with great interest as Ed described his project. Thousands of people all over the world, especially in the US, build their own plane. Many of them use auto engines, with the Subaru Boxer engine being one of the most popular. Ed should join the EAA, if not already a member.

I am building a RV-7A with a Subaru engine. As with many who have bought the same engine kit I did, I sure wish I’d gone with Lycoming. I’ve got $50k and 5 years into what was sold as a “complete FWF package” and turned out to be FAR from that.

Ed also mentioned that his proposed Subaru engine came with hoses and parts, etc, indicating that he’s planning to buy a FWF (firewall forward) kit, as opposed to buying an engine and making the mount and other FWF components himself. I’d urge “buyer beware” in this area. NPR may block mentioning any particular brands of FWF supplier, so I won’t specify any brands here, but I do urge looking carefully into the customer satisfaction of your FWF kit supplier. There are two Subaru FWF providers that have gone bankrupt after ripping off customers; taking money, but not supplying engines. There are two remaining Subaru FWF providers. One has significant reputation problems, the other does not, as far as I know. I got my FWF from the former.

You can get extensive details of my building experience, and particularly the Subaru FWF experience, on my web site at:

The bottom line in my experience is that a Subaru engine is much better in theory, but if you want to fly your plane, rather than tinker with it endlessly, go with Lycoming. If you’re only considering the Subaru based on price, I’d especially avoid it. Most people using Subaru engines do it for the more modern technology. There are many people successfully flying with Subaru (and other auto) engines, but there are also a lot of us, particularly customers of this particular Subaru FWF supplier, that have been bogged down for years solving technical issues that the supplier overlooked.

If you do go Subaru, make sure your electrical system is bulletproof and redundant, because without electricity, these engines do not run. A Lycoming uses old-fashioned magnetos, but does not require electricity to run. There are drawings on my web site, showing how I did my electrical system.

Avoid any auto engine with factory ECU. The factory ECUs are made for auto use and have many built-in auto safety features that you don’t want in a plane. If an auto ECU detects an anomaly in inputs from sensors, it will go into “limp home mode”, where the engine will run, but will not produce enough power to stay in the air. A German customer of the same FWF kit I have crashed his beautiful RV plane when his Subaru ECU inexplicably decided to go into limp home mode. Since then, most of us customers of that same FWF supplier have torn out the auto ECU and installed a simple reliable aftermarket ECU.

Engine cooling has been another area of concern, problems, and re-engineering our FWF kits.

Lots more info about all this on my RV builder’s web site.

good luck with it,

Ed I would listen to that last post. The money savings are probably an illusion. You can buy a used Lycoming after all, and think about it, what do you think the resale difference is between an RV-7 with a subaru vs a lycoming? I’m all for tinkering but maybe you should do an auto conversion on your next plane so you have something to fly while you tinker. Life is short and your medical is not forever. I don’t like to mention it but if your going to insure your plane you should check that you can with the soob.

Thats why they call it experimental. I believe it is a misunderstanding that aircraft engines are expensive because they are reliable. They are expensive because they are manufactured in small quantities and they have to be certified by the FAA. They are made with 60 year old technology because, again, they are manufactured in small quantities and they have to be certified by the FAA. The problem with auto conversions is that there are so few of them that virtually each one is a one off and so the engineering, testing and refinement is most likely incomplete. As a small plane builder it hurts to pay more than the price of an entire car for something that burns leaded gas ,is pretty fuel inefficient, and hasn’t really changed since the Truman Administration. Unfortunately there just isn’t enough of a market to make a new engine feasible. Oh, and that “2000+ hours without any major issues” is just not true unless you have the luck of a lottery winner.

I worked with a guy who built his own plane and then killed himself flying it. He was a good pilot, but the plane was not.

There is a long list of people who did this, such as singer John Denver, and another well know person who killed himslef recently.


Hey knee jerk, you could have just said “go with the certified engine.” Alaska Airlines? Ed is not insane he is just enthusiastic and open minded there is no call to be rude and make snarky comments about the NTSB and crashing. As for talking to an A&P what good is that going to do? Ed should talk to people who have tried a soob firewall forward package from the guy he wants to get it from. He most likely will discover that it isn’t really an equivalent experience to a lycoming and often gets replaced by an aircraft engine after an expensive time consuming interlude.

Hello Ed,

Your story gave me a chuckle, as I once went through the same airplane engine sticker shock and selection turmoil. We had a vintage single engine whose airframe and avionics were pristine but the engine reached end of life shortly after purchase. I looked into car engines and discovered that they will not reliably take the flight duty due to the nasty effects of gravity, centrifugal force and air density variation associated with motoring into the skies.

You would be missing a pressurized oil pump & reservoir, needed for continued running in unusual attitudes…even if you don’t take up aerobatics, you would not want to be trying to pull out of an accidental spin or slip and find gravity and centrifugal force have pulled the oil away from the engine supply port.
The carbureation issue is complex since you will be climbing ( hopefully) way above the roof tops, maybe up to as much as 10,000 ft. without oxygen and decreased air density will create a fuel mixture issue. I do not know what if any type of auto carbeurtor is set up to accomodate rapidly and frequently changing air density. Also the fuel supply system of an auto will not be set up to feed continually in unusual attitudes. You probably have thought of all this already and were just having a bit of fun with the guys…
Too bad you live far away, since I am working on restoring an old sportscar, and the remaining 2 bays of my garage are free! No greater fun than having a partner in crime during an airplane or car project.

Say, check out ebay and search lycoming engine. Just checked and there are several used ones starting at $5K.

Wish you luck with it & wish I could see it come together. I know for sure from experience that a wing will fit easily in a living room long-ways, on saw-horses. Also a kitchen pensinsula counter makes a perfect middle support for a wing set perpendicularly, with shimmed-up saw-horses at wing tips. Just watch out for fumes and keep windows open if working with epoxys and solvents or you’ll be flying way before the engine is installed…

Am curious what the kit instructions say about engine selection. An old mechanic friend’s favorite saying was “When all else fails…read the instructions”. I admit to having to resort to doing just that on a few occasions. However, it seems that the most fun and learning came from holding off as long as possible before reading the directions. Also many, many laughs.

If it was me, before I went for the first flight, I would hire an A&P certified mechanic to check it out thoroughly first, even if it is in experimental category… just for a little peace of mind.

There may be a blogspot or group somewhere on the net for other buyers of your same kit and that would be a good place to learn from other’s experience, what works ( and also warn against unfortunate difugalties)

Wish you the best with it. Have fun and keep your sense of humor.

best regards

Comment: there is a typo in the link listed above. One too many letter e’s. It sends you to a European Evangelistic theology group…maybe a strange coincidence to a possible future need for Ed… if he goes with the auto engine.

anyway the correct link to the Experimental Aircraft Assoc. is

Well Ed, there is a lot of good advice here about using one engine or another, but a few other thing about using aircraft engines. If you or at a airport and need to have the engine worked on there a A&P’s there to do the work (that’s a aircraft mechanic). The engines are designed for aircraft and there a many issues that are not consider in automobiles like weight, power output, cooling, mounting of the engine, torque, CG or Center of Gravity, mounting the right prop and others. An engine with to much power for the airframe will get you killed or under powered. Torque or asymmetrical propeller loading will turn the airplane on it side if you use to much power on takeoff that’s if you don’t have the rudder to compensate. There are many other issues to work out. If you don’t know how to work on the engine of a car then there are many problems using a auto engine. If the kit says to use one engine and aircraft type better stay with that as I’ve seen people die in planes like this or badly inured. They make engine for aircraft in a different way for a risen that’s better for your application. Good luck. Oh P.S. I’m restoring a Cessna 172-D and am learning alot more than I very did before. Dan

Lots of good info here. Don’t underestimate the difficulty of adapting a car engine to airplane use. Porsche tried to break into this market with their flat 6, seemed like an obvious fit, but found it very difficult. I don’t know if they’re still trying.

I think this guy should be allowed to put whatever car engine in his airplane he likes. As long as he dosen’t take passengers and flies over the ocean. A brand new Toyota Camry engine should give him the required speed to get to altitude. And then some.

Yes he can put what ever engine in the plane he wants, but you still will die any way if you do it wrong. - Wal-Mart heir dies in plane crash - Jun 28, 2005

Wal-Mart heir John Walton died Monday when his ultralight aircraft crashed after taking off from an airport. He was a Billionaire and a good pilot.

A not so subtle hint: My point was was he could help improve the gene pool while implementing his dumb idea without hurting anybody in the process. (Maybe he can fit one passenger, come to think of it).