EPS Goes Experimental

There's no secret we're fans of the in-development Graflight V-8 currently under development by Engineered Propulsion Systems. A completely new flat-8, turbocharged diesel with gear reduction, water cooling and sophisticated engine management by Bosch, the EPS engine promises to move general aviation piston engine technology into the modern era in one gigantic step.

But until AirVenture this year--where EPS is exhibiting--the new Graflight engine was destined strictly for certified applications. That appears to be changing.

EPS' certified-only stance was driven by the technological necessity of engineering each variant of their engine to the recipient airframe. This is still true, but with the strong interest shown by some kit manufacturers--meaning they're eagerly waving their checkbooks--EPS is considering Experimental fitments as long as EPS engineers the complete firewall-forward package.

This could easily breathe new life into legacy go-fast Experimental kits given the Graflight's unique combination of impressive power and fuel economy. Designed to fit existing 540 and 550 engine mounts and weight envelopes, the Graflight engine does not pose daunting installation challenges.

Of course, there are tall hurdles of initial cost (more expensive by some compared to the 350 horsepower turbo offerings from Lycoming and Continental) and unknown long-term reliability, but the promises of increased range, operating ease, practicality of Jet A fuel, TBOs ultimately as high as 3,000 hours and a 385-hp power rating are proving too great to ignore.

EPS reports FAA certification should be in hand by the end of this year or the first quarter of 2018 at the latest. The first 15 conformal test engines are being built as part of certification, a process the FAA and EPS are somewhat learning together as the FAA hasn't certified an all-new engine in over 40 years!

The engine shown here is in EPS' Air Venture booth and is the last to use billet aluminum timing and other covers. Castings for these parts are arriving, so all future engines will essentially be production engines. This is also our first look at the flat-8 without its large charge air cooler covering up the top of the engine.

Tom Wilson

Tom Wilson is a professional magazine writer and nurtures an ongoing affair with all things internal combustion. His writing is most often found in automotive magazines, but aviation is his first love. Working as a line boy, he learned to fly while in high school, but still hasn’t mastered the art of keeping a paper chart in an open cockpit.

8 Replies to “EPS Goes Experimental”

  1. Just looking at the bulk size of that engine (photo lacks a comparative perspective) I don't see how something like that could ever fit into an experimental design like an LSA. Diesel reciprocating engines are by design long lasting and far more fuel efficient than gasoline. My diesel farm tractor proves that point compared to its gasoline cousin. I hate electrical ignition systems which require some tinkering compared to compression ignition which essentially requires none. If our cars were diesel powered we probably wouldn't need to import a drop of crude oil.

  2. Would be nice with one in the 180 - 220 HP range also it would be perfect for the Glasair Sportsman in all configurations.

  3. I had been a big fan of Diesel engines for most of my life. There is a lot of misconceptions around Diesel engines and the public needs to be educated by all of us. I find it strange that we do not embrace an engine that was originally made to run on peanut oil instead of petroleum

  4. The "Graflight V-8" is a flat-8. In their literature EPS uses the term "V-8" --I'm guessing--to connote the power and presence "V-8" has in the marketplace. EPS does explain in their brochures that their "V-8" has a bank angle of 180 degrees and is thus a flat-8.

    There are 4-cylinder and 12-cylinder variants of the flat-8 engine well in the future, but for now development is concentrated on the 8-cylinder engine.

    The engine does look bulky in the photo, but it is actually slightly shorter than 6-cylinder gas engines thanks to the smaller diameter cylinders being more tightly packaged. This is possible because of the liquid cooling (no bulky air cooling fins), which also allows a shorter, stiffer crankshaft.

    Weight of the 8-cylinder engine is approximately 55 lbs greater than a conventional 540/550, but EPS is quick to point out their fuel consumption is so much less the total systems weight (engine plus fuel, PSRU, coolant, etc.) favors the EPS after a few minutes in flight.

    I must also post a correction: the Graflight V-8 specifications listed in the Air Venture brochure show a power rating of 380 hp and not the 385 hp I gave in the article above. This is my mistake due to a faulty memory and Air Venture overload.

    As for the EPS engine being suitable for LSA airframes: no. The 8-cylinder is designed to compete in the 320 to 420 hp range and is far too large, heavy, powerful and expensive for LSA use.

    Speaking of price, there is no word on pricing from EPS, but I can't believe this totally new engine from a new company can undercut or equal the list price of the most sophisticated 350 hp 6-cylinder Lyc's and Continentals it will compete with. The economics of its development and its capabilities demand a price premium. I expect that premium to be notable but within striking distance of competitive engines--meaning the EPS engine will compete in the marketplace by virtue of its fuel economy, single-lever operation, increased TBO, elimination of shock cooling and fuel availability worries.

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