John Luft, COO of Advanced Engine Technologies, Inc. (AET; Los Angeles), is immodest when describing his company's OX2 engine. "It's the first fundamental change to internal combustion engines, probably since their inception." The object of his bold if modified claim is an aluminum drum that has a diameter of 12.8 in., weighs 125 lb., and looks like an industrial electric motor. In reality it's an eight-cylinder engine that can generate 150 ft-lbs. of torque at just 400 rpm.

The brainchild of an Australian inventor, the OX2 could deliver many of the items on automakers' wish lists. It has only six major components and doesn't rely on exotic materials, which should make it comparatively simple and inexpensive to manufacture. The OX2 also has one-third fewer moving parts than a conventional piston engine, and can generate high torque at low rpms, which reduces wear and the need for maintenance. As if that isn't enough, Luft claims it can run on a variety of fuels including gasoline, CNG, LPG, methanol, ethanol and even hydrogen. Finally, and perhaps most importantly, its small footprint and low weight should increase packaging freedom and fuel economy.

Advanced Engine Technologies, Inc. President Carroll Shelby and COO John Luft with a cutaway of the OX2 engine and a full-scale example. The company hopes that its lightweight but powerful engine will find its way into future hybrid vehicles.

POTENTIAL. So is this the real deal? Well, the performance of the initial OX2 prototypes was enough to persuade automotive icon Carroll Shelby, creator of the Shelby Cobra and a man with more than a passing familiarity with engines, to sign on to lead the development. Even GM is interested enough to have signed a letter of intent that calls for AET to provide it with testing results. This is despite the fact that the OX2 won't be able to generate enough horsepower in the foreseeable future to be used as the sole power source for an automobile. Instead, says Luft, "The engine's first point of entry into automotive will be hybrid vehicles."

In fact, that's the thrust of the deal with GM, to evaluate the OX2 with an eye toward future hybrid applications. At one-quarter of the size of a small-block V-8 and with a tremendous power-to-weight ratio, the engine may be the perfect candidate for hybrids. But while the OX2 excels at generating low-end torque, its design makes achieving higher rpm problematic. Therefore, the latest testing goal is to achieve 1,000 rpm, at which point it should develop about 60 hp.

LIMITATIONS. AET plans to have a production model ready within 18 months, but not for powering a vehicle. Rather, it will be a stationary generator designed to replace the massive diesel units serving as back-up power supplies for buildings. Once the initial bugs have been worked out there, the company hopes to move on to the more demanding automotive market. The current strategy is to license production of the OX2 to a manufacturer, but Luft says that AET has not ruled out the possibility of setting up its own plant.

Of course, the road to replacing conventional internal combustion engines is littered with clever designs, from the Wankel to the Orbital. All of which faced what Luft calls AET's "biggest challenge," namely "that the automotive industry has billions invested in the current engines" and is loathe to get behind radically different designs. Which is why he thinks hybrids–which need consistent, clean power from a lightweight powerplant–may open some doors. If the OX2 can meet that test, it may very well find a niche for itself among its more traditional counterparts.

How it works The OX2 jettisons many of the expectations of how an internal combustion engine should operate. It has no crankshaft, camshafts, oil pump or valvetrain. Pistons are connected by rings (called "plates") that move via rollers along a fixed cam. A constant-velocity roller bearing joint on the plates allows them to translate reciprocating motion into rotary motion, while the cam lobes force the pistons into the cylinders. Combustion sends the pistons back down, which rotates the plates and circular engine block. Power is transmitted directly to a drive shaft that runs through the middle of the assembly. In place of a valve system, the OX2 has a simple port plate with a 3-mm thick full floating seal that covers the single port at the end of each combustion chamber. Unlike a traditional four-stroke internal combustion engine, there is a firing every revolution and two pistons always fire together which gives the OX2 its high torque to rpm ratio. AET claims that the OX2 has a leverage 6.6 times greater than that of a traditional piston engine design. But the downside is that, as AET's engineers coax more rpm out of the engine, the centrifugal force lifting the pistons from the track increases. Says Luft, "We have spent a tremendous amount of engineering time looking at modifications that will keep the pistons on track." Ultimately, resolution of this problem could hold the key to the OX2's potential success.