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What Will Replace The IO-360?

We recently celebrated the 100 year anniversary of flight.

In 1957, (or 54 years after the Wright Brothers first took to the air), Lycoming put the IO-360 into production. It was a derivative of the IO-320 that was designed in 1947.

To put both of these antiques in perspective, the first satellite was launched in 1957... the U.S. did not have a single jet transport in service.

In spite of technological progress in the last forty-six years, both the IO-360 and IO-320 are still in production. And many would argue that even today, the IO-360 is the best engine available in the 200 hp category.

Is this engine the best we can do for the next 46 years? If so, then general aviation does not have a very bright future.

But to truly look at options, one must look at fuel options:

80 octane LL Currently available though getting harder to find. Long term availability questionable.

Automobile gas Long term availability but with varying levels of quality control. Doubtful widespread airport availability.

Jet fuel Widespread airport availability.

So what are the engine options?

Lycoming IO-360 Very reliable 4-cylinder engine. Rough running and noisy. Keep in mind that with every turn of the prop, there are only two cylinders firing. The logic here seems to be, it is an OK engine for a $180,000 aircraft but not something you would want in your $60,000 Lexus.

Continental IO-360 Six cylinders provide a little smoother operation than the Lycoming. Since both are 4-cycle engines, each cylinder fires only once every two prop rotations. Translated, two bangs per revolution for the Lycoming, three bangs per rev for the Continental.

Superior XP-360 An un-certified clone of the Lycoming IO-360. Same four cylinders, same four cycles, but the company claims better materials and newer fabrication methods, lower costs.
www.superiorairparts.com

Crossflow CF4-20T A Subaru automotive conversion. Lower in cost, smoother running than the Lycoming. Burns premium auto fuel or 100 LL. Liquid cooled. Weight equivalent to IO-360. Uncertified.
www.crossflow.com

DeltaHawk V-4 A new liquid cooled turbo-diesel under development in Racine, Wisconsin. Designed for jet fuel, if they can meet fuel flow objectives, it would use about 7 gallons per hour vs. 10 for the IO-360. Expect the weight to be higher than the IO-360 but it is like a comparison between a turbo-fan and a turbo-jet, fans weigh more but the weight is quickly offset by lower fuel flows. The engine is 2-stroke, 4 bangs per revolution.
www.deltahawkengines.com

SMA SR305-320 A French based company with a blue-blooded pedigree represented by shared ownership from SNECMA, EADS and Renault. The engine is a diesel that burns jet fuel. While considerably heavier than other engines in this category, the engine is certified and in production. Four-stroke, 2 bangs per revolution. Very expensive, but the only certified diesel available.
www.smaengines.com

Centurion 1.7 Another certified diesel, this one by Thielert, a German company specializing in high performance racing engines. The Centurion 1.7 is only rated at 135 hp so technically is not in the same category of the IO-360 but perhaps a bell weather of things to come. One indicator, it weighs a chunk. But it is a 2-cycle providing 4 bangs per revolution.
www.centurion-engines.com

Continental GAP Jointly funded by NASA and Continental Motors, the program has been in the public eye since 1996 as general aviation's hope for the future. In the last couple of years, information on the project has been sparse. In February 2002, Continental released info showing the engine installed in a Cessna 337 and undergoing taxi tests.
http://www.grc.nasa.gov/WWW/AST/gap1/sld001.htm

Vesta A sleeper with a low key exhibit at Oshhosh 2004. They are converting new, out of the box Corvette engines that can produce 300-350 HP at affordable prices. Under $15,000 for the engine, reduction drive and prop.
http://www.vestav8.com - most comprehensive info is in the FAQ section.

Wilksch A UK based start-up headed by a couple of experienced engine builders and funded by some government money. There approach is to start with a 3-cylinder 120 hp diesel and a 4-cylinder 160 hp version. Both are 2-cycle...4 bangs per revolution. These engines are flying and Wilksch AirMotive is taking orders. www.wilksch.com

For more good reading on the diesels for light aircraft: www.dieselair.com

And don't miss this reprint of an article that ran in the November 2003 issue of Today's Pilot by Roger Miller:

Aero-Diesel Update


CONTINENTAL MOTORS revealed more details on their joint venture with HONDA to develop a water-cooled, flat-four cylinder, 225 hp engine. Designed to burn 93 octane unleaded automobile fuel or 100 LL av gas, the 310 pound engine is in development flight testing but several questions remain unanswered:
1. What will the performance numbers look like?
2. How much will a production engine cost?
3. When will the engine be available?
4. Will it be any quieter or smoother than production IO-360 engines?
5. Will there be any advantage over existing engines (read why did they bother building this engine)???

BOMBARDIER RECREATIONAL PRODUCTS (ROTAX)
Two new engines are being developed by BOMBARDIER. One is a normally aspirated 220 hp V-6, the other version is a turbo-charged version of the same engine boosting horsepower to 300 hp. Both are liquid cooled and both are designed to burn either 100 LL or MoGas.

The main design objective of these engines appears to be a reduction in aircraft noise. While the engines will turn over 7,000 rpm, a gear reduction system will reduce prop rpm to 1,550 to 1,700 rpm. Fuel economy is expected to be quite good as well.

The weight to horsepower ratio of the 300 hp version is quite favorable, the same can not be said for the 220 hp version. It will be heavy...plus the prop will add more weight than usual.

To absorb the horsepower of these slow turning prop shafts will mean either a large diameter 2-bladed prop (with a tall landing gear to boot) or multiple (3-4) bladed, wide-chord (paddle type) propellers.

DELTAHAWK announced they have ground tested their diesel engine in an inverted configuration.

In the "V" configuration, the prop shaft was low which would require a designer to elevate the engine to get ground clearance for the prop. This in turn puts the engine up high where it would compromise the pilots field of view.

One can only wonder why the engine was not designed inverted from the start.

MAZDA, the new RX-8 has a new engine that may attract the interest of companies converting the rotary engine. According to MAZDA, the power plant will be 30% lighter, 20% smaller and uses 20% less fuel than the rotary engine that powered the RX-7.

If these numbers hold, this engine could have potential.