Rambler’s rotary engine project of 1964 never went anywhere, but that doesn’t make it any less fascinating. Here’s the story behind this oddball powerplant. 

Like many of you, no doubt, we grew up reading the great old workbench magazines, including Popular Mechanics, Popular Science, Mechanix Illustrated, and so on. One wonderful feature of these handyman’s journals was their perpetually optimistic take on future technology. Each month we learned that the next major breakthrough in automotive engines was just around the corner.

Take, for example, this cover story from the October, 1964 issue of Mechanix Illustrated, which describes an experimental rotary engine program then underway at American Motors. Of course, we know today that the project never went anywhere, but that doesn’t make it any less fascinating. Let’s take a closer look.

According to our Mechanix Illustrated article, the Rambler rotary engine was a joint effort of American Motors and Renault, and patent filings from Renault at the time bear that out. Like the Wankel engine then in advanced development by NSU, Mazda, and others, this powerplant was a rotary, but instead of the modified Reuleaux profile of the Wankel rotor, used a four-lobe arrangement—rather like a lobular pump. The illustration above and it original caption break down the configuration’s four-stroke cycle.

Information is scant, but from 10,000 feet we can guess that the Rambler-Renault rotary shared many of the benefits of the Wankel design, and its drawbacks as well. The design is compact, lightweight, and low in component count, producing an attractive power-to-weight ratio. Meanwhile, emissions and fuel economy would suffer due to the high surface-to-volume ratio, and rotor sealing would be an eternal uphill struggle. We don’t know this, but we doubt the Rambler-Renault system moved the ball forward in any significant way.

The Mechanix Illustrated story speculated that with the rotary’s compact size, it would work well in a transverse front-wheel-drive application, as shown above. There is no evidence that the four-lobe rotary progressed beyond the prototype stage, but we do know that American Motors and chairman Roy D. Chapin Jr. maintained their interest in the basic rotary concept well into the 1970s.

The automaker continued to experiment with the Wankel rotary, on its own and in conjunction with Curtiss-Wright, and later planned to use a General Motors-built Wankel in the 1975 Pacer. But the GM Wankel never made it into production due to a host of problems of its own, and when the Pacer appeared in the showrooms on February 28, 1975, it was powered by a very ordinary American Motors inline six.