Blast from the Past: NASA's Stirling-powered AMC Spirit
NASA Stirling-powered AMC Spirit - Click above for image gallery
Over the last few months, Segway-inventor Dean Kamen has made headlines for installing a Stirling engine in an older EV from Th!nk to create an extended-range electric vehicle. Interestingly, this is not at all the first time a Stirling engine was used to power an automobile. Apparently, the U.S. Department of Energy tasked NASA with the job of fitting an American-made car with a Stirling engine way back in the 1970s when the first oil crisis had the country in its grasp.
After realizing it lacked a certain amount of expertise in refitting automobiles (as opposed to, say, space shuttles) with new engines, NASA reportedly contracted AM General to do the actual conversion work. The result of all this effort is the AMC Sprit you see above. In later years, NASA's Stirling projects also included an AMC Concord, a GM G-chassis cube van, a Dodge D-150 pickup truck and a 1985 Chevrolet Celebrity.
According to Hemmings, these vehicles were tested extensively for over 50,000 miles and were able to achieve average efficiency that ranged between 18 and 28.5 miles per gallon. Perhaps the idea of using a Stirling engine as a generator isn't so crazy after all? Thanks for the tip, Sid!
Gallery: NASA AMC Stirling prototypes
[Source: Hemmings]
Reader Comments (Page 1 of 1)
Dan 3:45PM (7/08/2009)
Jeremy-
From what I read, NASA and AM General simply used the Stirling engines as the main propulsion for the cars, which was their biggest downfall - the cars couldn't produce the on-demand throttle response of a regular ICE vehicle. They apparently never thought about combining a Stirling with a generator in an EV as Dean Kamen did.
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Chris M 4:24PM (7/08/2009)
Yep, to step on the throttle and have the engine respond a minute later didn't quite work. Then the fuel economy improvement was modest, and the radiator had to be huge, and, well, it just wouldn't do.
Of course, used in a hybrid design, Stirling engines can be run at their most efficient power and speed to achieve much higher fuel economy, the electric motor and batteries can supply the immediate throttle response, and the continuous combustion means emission control is much easier. Of course, multi-fuel capability is a given, almost any heat source can be used.
Pete 6:34PM (7/08/2009)
Why don't they have multi engine design, since 70% of the energy from the oil is lost as heat, why don't we have a smaller ICE engine combine with a stirling engine using the heat from the ICE to drive a generator?
In that configuration we should get 60% efficiency from the fuel?
Mike Z 11:29PM (7/08/2009)
Also based on the slide deck the engines were about 4 lbs per HP. Modern ICE engines are almost 1:1.
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casper 12:39PM (7/09/2009)
Indeed, Fords Stirling engined car's downfall was also in the difficulties of the rapid changes in rpm required for a road car.
Whilst a Stirling engine as a generator for an electric car is an idea and has benefits (quieter and far far wider fuelling options), the Stirling engine is less efficient than the ICE as Volvo Cars found as part of their ReCharge research programme
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