GM’s 1930s Rear-Engine Experimental Cars Had The Weirdest And Stinkiest Engines Ever

If we had to collect one time in story to be an automotive engineer, I’d have to collect a mid-to-late 1930s. Well, as a Jew, there’d be some flattering critical trade-offs about that era, of course, yet as someone who loves rear-engine designs, it was a Golden Age. While many of a rear-engine pioneers we routinely consider about were European, there was some fascinating work going on in America, and some of that work was distant some-more radical and bizarre than you’d think. Like what GM was doing.

Back in a ‘30s, everybody seemed to determine that a destiny would be dual things: rear-engined and streamlined—at slightest in a singular approach they accepted aerodynamics behind then. Almost any vital automaker was doing during slightest some investigate into light, aerodynamic-ish, rear-engined cars.

Starting with a work of Edmund Rumpler in a 1920s, a thought that a destiny of cars would have a courage in a butts shortly became a go-to template for destiny automobile concepts. This line of meditative shabby designers like Porsche, Ganz, Ledwinka, Tjaarda, and others. Its many famous and successful fulfilment was expected a iconic Volkswagen Beetle and, later, a Porsches 356 and 911.

Tjaarda’s Lincoln Zephyr rear-engine concept

During a heated heyday of a investigate and growth of these cars in a 1930s, there was roughly an tacit requirement for any vital association to have some kind of rear-engine plan happening. Mercedes-Benz was building their 130H and 170H cars, Tatra was creation their big, superb V8 rear-engine cars, there was a Stout Scarab, and so on. In America, a Big Three had their possess projects, like a REO Doodlebug or John Tjaarda’s Lincoln Zephyr designs for Ford, and, of course, GM wasn’t about to be left behind.

Martia I

GM’s rear-engine destiny economy automobile plan was started in 1933 by GM conduct Charles Kettering himself, with O.E. Schjolin streamer a team.

In fact, if we decider these cars on a scale of technical weirdness, GM had reduction of a possibility of being left behind than a born-again baby on Rapture day: these cars were deeply, gloriously weird.

In altogether design, they weren’t that conflicting than anyone else’s rear-engine initial futuremobiles: vaguely beetle-shaped, lots of vents on a back, yet sincerely conventionally sized and styled. GM’s were unibody designs, that is rather novel, yet not that shocking.

What was intolerable was a engine design.

The engines used for a 3 initial cars a group made—called Martia I, Martia II, and a less-poetic AD-800—were X-4-layout engines.

Right there, a radial-type engine with a cylinders laid out in an X, that’s copiousness uncanny already, yet that’s only hardly scratching a uncanny frosting off a uncanny cupcake of these engines.


These X-4 engines indeed had eight pistons, since any cylinder was indeed dual together cylinders with dual pistons, with one piston doing a intake, one doing a exhaust, and connected by an inverted-U-shaped explosion chamber.

These were water-cooled engines, and, in a fact that predicts complicated hypercars like a Bugatti Veyron and Chiron, a cars used mixed radiators. The Martia we used 3 (two front, one rear), while a Martia II and a AD-800 done do with only a front two.

If that’s not uncanny enough, these were two-stroke engines, and had a Roots-type supercharger as well. Except, get this, a supercharger wasn’t used for a normal pursuit of compressing a fuel-air reduction to send into a intake manifold, yet for a conflicting job: to improved remove a spent fuel-air reduction out of a empty manifold, and then, since two-strokes don’t customarily bake all a initial time, promulgation that reduction back through a intake manifold.


It was arrange of like a initial exhaust-gas recirculator system, and Schjolin’s group claimed it done a dual cadence 15-20 percent some-more fit than a allied four-stroke. They also claimed these cars got 45 MPG.

So, because didn’t these experiments take off?

I have to suspect that a infuriating complexity of these engines (especially compared with what GM was building in a ‘30s) had to be a factor, yet there is one most foreigner and funnier reason.

According to Michael Lamm of The Old Motor,

One of a good drawbacks of these powerplants was their empty fragrance during light loads. George Hallett, one of a engineers we talked to about this plan behind in 1971, pronounced a empty smelled “…like a multiple of rip gas and skunk.” Another engineer, Marion Fast, told me, “…these were a stinkiest engines ever built – positively unfit from an emissions standpoint, even in those days.” But by force-scavenging both a 130 and a 160 with a same-sized siphon (supercharger), a group found that a incomparable engine had reduction blow-through and a reduction repulsive empty smell.

So, yeah, we can see how an fragrance of “tear gas and skunk” competence be a arrange of small whinging fact that would spin off certain strict car-buyers.


Engines subsequent from these designs were tested in aircraft, where we suspect a smell was reduction of an issue.

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