The idea of combustion wave turbines has been around for a little while, but they’ve never been useful in automotive because they generally don’t produce enough torque to move a vehicle without extremely advanced (and complex) gearing.

Now with plug-in hybrid technology (aka range-extended electrics, RE-EVs), these engines as generators are a very viable idea.  Michigan State University researchers are now working with this engine technology as part of a Department of Energy ARPA-E program to complete prototype development of this disc wave engine.

The advantages are huge.  The engine could be three-and-a-half to five times more efficient than a standard gasoline piston engine when used as a generator for electricity production.  At the same time, it would be 20% lighter and 30% cheaper to make.

This new design on the wave concept is a wave disc engine, versus the older wave rotor technology produced by the same Michigan State research group in collaboration with the Warsaw Institute of Technology.

Consider this:

The engine in the 2011 Chevrolet Volt is a 1.4L gasoline injection engine with four cylinders and putting out about 55kW of power through its linked generator while the engine itself is capable of a maximum output of 111kW.  It weighs about 380 pounds* and gets 37mpg (in gas-only mode).

Replacing that with one of these wave disc engines/generators (WDG) would mean, at the same power output, that the engine would weigh about 300 pounds and would be capable of up to 185mpg.

Here’s video of the prototype in action:

*GM has not released full engine specs in regards to weight, but given the engine’s output and similar GM engines with iron cores and aluminum heads, this is a likely estimate.

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