Pontiac X-4

The late Pontiac Enthusiast writer John Sawruk was one of Pontiac’s engineers who briefly worked on the X-4 back in the day. He speculated that the very detailed information gathered by Popular Mechanics must’ve been leaked on purpose. Plus, it was him who got his picture taken without him knowing.

One of the realities of having a favorite topic, in this case a particular brand, is that you soon learn all that there is to learn about it, especially if said brand is no longer with to make new things to learn about. It doesn’t help if one is only focused on a certain time period, which also limits what one can learn. So not only learning about the existence of the Pontiac X-4 not only came to a complete surprise, but also with a degree of happiness to learn something new about one of my favorite topics: Pontiac.

What is a North-American car company to do with the nation’s fetishism for the Volkswagen Type I (you know, the Beetle), a car that even back in its inception was as far removed as a four-wheeled conventional automobile could be (rear-engine, torsion bar suspension, air-cooled, etc.)? Why not build one? Something that made the Chevrolet Corvair seem like a Buick.

Enter the Pontiac X-4.

The name comes from the engine, which is definitely the heart of this machine, and for good reason. It’s just so unique and clever! For starters, it’s not even the staple of fuel-sipping economy car engines, the inline-4. It’s an air-cooled two-stroke, X-shaped, four-cylinder radial engine, said to be the descendant of pre-WWII experimental engine X259, a GM product that was a liquid-cooled, two-stoke radial engine that found its way in test cars (outside of the Popular Mechanics article, you won’t find anything on it. I checked. Feel free to prove me wrong). In short, it’s basically an airplane engine. But it isn’t.

Before we continue, we must step back and discuss that this engine is a four-cylinder radial engine. This type of engine has its cylinders placed around the crankshaft, instead of being arranged in a line or a ‘V’. By nature, radial engines have an odd number of cylinders (3, 7, 9, etc.) to make their designs work with the four-stroke firing order. The only exception to the rule would be if the engine worked with the two-stroke firing order, that’s when the radial engine went even (2, 4, 6, etc.). If you want to be pedantic, you could say that the X-4 radial engine is just two two-stoke flat-twin engines trying to be an ‘X’.

But what an ‘X’!