The way this old wives’ tale is usually told, the Big Three have kept superefficient engines under wraps in some kind of unholy attempt to keep the world dependant on petroleum.

The truth is that inventors have devised numerous engine technologies over time. Several of them are more efficient than the internal-combustion engines that have powered vehicles for the last 100 years. And they all work great, on paper. But there’s a wide chasm between an engine that’s efficient in principle and one that performs reliably even after 100,000 miles of use. Economics haven’t favored putting money into radical engine designs no matter how promising they’ve seemed.

That situation is changing in the new world of $4/gallon gasoline. No question a lot of propulsion research concentrates on electric motors. But the recently concluded Society of Automotive Engineers World Congress showcased combustion technologies that probably wouldn’t have gotten a second look just a few years ago. Among them was the Scuderi split-cycle engine recently covered in
Machine Design.

There, too, was something called the Schoell cycle cyclone. It’s dubbed an external combustion engine because steam serves as the working fluid. The device looks a little like a radial engine from a prop plane turned on its side. Its claims to fame include low emissions and the ability to use a variety of fuels. The inventor says the first application for his creation is in lawn mowers, where a 3-hp version will be ready in two years.

Another novel design on display at the show was the two-stroke opposed-piston, opposed-cylinder engine developed under a Darpa contract. The combustion chamber on this diesel power plant resides between two pistons oriented in a plane opposing each other. Combustion pushes on both pistons in the power stroke. Piston pairs sit on either side of a crankshaft so four-piston modules can be bolted together to get more power.

One benefit of this idea is weight savings. The 320-hp prototype puts out 125 hp/liter and comes in at 1.2 lb/hp. The engine is designed for ground vehicles but the inventor admits, “There is still a lot of development ahead of us.”

The Army’s Tank Automotive Research, Development, and Engineering center has also sponsored work on a Wankel rotary engine modified to run JP-8 jet fuel. This gizmo fits in an Abrams tank and generates electricity when the tank’s engine is off. It weighs a lot less than the equivalent batteries and burns less fuel than running the big main engine just for electrical power.

In the coming weeks you’ll be able to see all these devices on EngineeringTV.com where the developers go into detail about how these inventions really work. Meanwhile, paranoids who can no longer make wild claims about plots among the oil companies should start looking for a new hobby. I would suggest further contemplation of what’s parked in Area 51.

– Leland Teschler, Editor

Leland Teschler