> Has the engine in the 172 been improved in that time period? The article says it has not, but I can't imagine using 60 year old tech like that.

It's not the exact same engine, but it's the same technology - an air cooled 360 cubic inch horizontally opposed 4 cylinder engine. Magnetos provide spark, and as far as I'm aware the fuel injection is mechanical.

"Modern" piston engines used in aviation are essentially 1950's technology. They're surprisingly reliable for what they are, but innovation isn't really happening in the piston world.

There was an interesting upgrade being worked on by a couple of guys in Florida. It turns out that the engines in these planes have an expected lifespan of 2,000 hours or so, and can't use gas with ethanol in it, and replacement engines can cost in excess of $20,000; these guys worked on a way to drop in a $5,000 Chevy Corvette engine and greatly increase fuel economy, reduce noise, reduce vibration, and supposedly increase reliability. When they asked the FAA to sign off on it as a replacement they were told that without redundant spark plugs/spark sources it wouldn't be approved. This makes sense when magnetos are expected to be rebuilt every 500 hours, but it killed the Corvette engine replacement idea.

Regulation slows innovation. General Aviation proves it IMO.

Dual plug heads, and dual distributor setups are available off the shelf for LSx engines in drag race applications. One wonders why they didn't do the conversion. Although new heads and twin dizzys would easily double the cost, that much reliable power in the aero world would still be a good deal for many.

FWIW, I once had a faulty spark plug in one cylinder in a Cessna 172 in Ondangwa, Namibia (and no, "burning it off" by running the engine lean on full throttle didn't fix it). So, I flew back to maintenance in Windhoek on the other spark plug, using IFR ("I follow roads") in case the other gave up (which it didn't).

This comment reads like an intro for a very interesting book.

So are you allowed to this to your own personal plane (engine swap with non standard engine)? Or do you still have to get FAA approval even for private use?

I guess I'm wondering if there's a grassroots community of people doing engine swaps on their planes?

For a type-certified airplane (roughly "one built in a factory"), such an engine swap would require a Supplemental Type Certificate (STC). The process of creating such an STC would require a fairly extensive engineering study as well as flight-testing to prove the new engine was suitable in all regards. During that time period of developing the STC, you would place the aircraft into "Experimental" category to do the testing.

While possible, economically "it's not going to happen".

For non-type-certificated airplanes, there is a large grassroots community around "Experimental-Amateur Built" (E-AB) aircraft. EAA (www.eaa.org) is the largest owner club; they put on "Oshkosh" every year, which is the world's largest fly-in (of E-AB and factory aircraft). In E-AB, the constructor of the airplane has nearly full latitude to choose their engine setup (and to change it later). My limited experience suggests that those who start with tried-and-true aviation-origin engines have a higher success rate with their projects.

Thanks for the info!

The Oshkosh eaa meet was always a lot of fun to go watch when I used to live in WI.

And that is the problem. These old Avgas burning carburetored dinosaurs are hugely inefficient. However, the effort required to certify new engine designs for light aviation is prohibitive, because they're never going to sell in numbers high enough to recoup the development/certification costs.

Diamond Aircraft in Austria are producing single and twin engine light aeroplanes with diesel engines, oriignally based on an automotive design. However, they've been through a bankruptcy event and are frankly lucky to still be manufacturing.

There are options to retro-fit diesel engines to the single Cessna range, but if I recall correctly, a deal for a new factory build with that option fell through a couple of years ago. Buy a new Cessna 182, still fill it with Avgas.

Aircraft piston engine efficiency is actually quite similar (measured in brake specific fuel consumption) to modern auto engines. The Lycoming O-320 in a Cessna 172 burns 280 g/kWh. Modern auto engines like the EcoBoost burn not much less -- ~250 g/kWh. See https://en.wikipedia.org/wiki/Brake_specific_fuel_consumptio....

Moreover, aircraft engines like the O-320 can run for hours at continuous max power output. Good luck doing that with a car engine.

Car engines absolutely demolish aircraft engines on emissions, though. They have O2 sensors, computer-controlled ignition systems, and catalytic converters, whereas aircraft piston engines have fixed ignition timing and burn extremely rich of peak (meaning massive emissions) at takeoff power. And on top of that, while little engines like the O-320 can burn ethanol-free autogas, the big piston engines like a Continental IO-550 require leaded fuel, adding another pollutant to the mix.

The diesel engines that Diamond sells now (from Austro Engine) are unrelated to the the old troubled Thielert diesel engines they initially used, IIRC.

Yes, but I'm pretty sure at least some of them are based on automotive diesel technology, such as those in the DA62

https://en.wikipedia.org/wiki/Diamond_DA62

https://en.wikipedia.org/wiki/Austro_Engine_E4

And the Thielert Centurion diesels were based on Mercedes Benz car diesels, by the way!

No, it hasn't. Or, there's been aftermarket options and multiple attempts to make more efficient engines, but many have had reliability problems.

When your life depends on it, you're more likely to choose the engine that has all of the kinks worked out, has proven reliability, and where the failure modes are pretty well known.

It's a pity, really:

* the avionics have improved immensely (solid state gyro instead of vacuum-pump driven mechanical gyro, for example, GPS, etc.)

* in tandem with that, cockpits have improved ("glass cockpit" with two or more huge screens instead of the traditional 6-pack of small instruments)

* there's been innovation and progress in materials (composite instead of aluminium)

But the engines are still the old dinosaurs from the 60s :-(

That's one reason many pilots are watching battery tech and electric engines with interest (so far, the specific energy of batteries is way too low, giving an hour of endurance if you're lucky).

This might be Stockholm syndrome, but I'm fairly happy with the 1960s-tech TNIO-550B (turbo-normalized, fuel-injected 550 cubic inch 6 cylinder opposed [boxer] engine) that powers my A36. The only significant downside is that it requires 100 octane fuel and the only certified option in the US right now contains tetraethyl lead(TEL).

There are several companies making unleaded fuel undergoing certification testing right now. It's not clear which one (if any) will "win", but I have high hopes that one of them will.

In terms of efficiency, that airplane does >200mph at better than 15mpg. That's not too bad, IMO. Better engine management tech would get me an easier workload as a pilot, but I don't expect it would yield meaningfully more power or efficiency, unless you were to raise the compression ratio (which typically requires higher octane fuel, and existing 100LL fuel is already pushing it, with a rich detonation performance of roughly 130 octane due to the benefits of TEL)