When you think of a three-cylinder engine, you probably imagine a little European compact car with an inline-three-cylinder engine that sounds like a sewing machine on steroids. However the three-cylinder engine has been around in various forms for a long time. They have been pushing boundaries since day-one and are still shaking up the status quo even in modern times.
Anzani W3 Fan Engine
Originally designed as motorcycle engines in the early 1900s, the Anzani — named for their inventor Allesandro Anzani — three cylinder engines were essentially air-cooled V-Twins with a third cylinder added on. The W3 engine fit into the frame of Anzani’s motorcycles exceptionally well, while making decent power for the time. Originally, the 88.5 cubic-inch models made 10-12 horsepower from their square 3.35-inch bore and stroke.
Eventually, the design was up-scaled to a 393 cubic-inch version, which produced 45 horsepower. While eventually moving to an inverted Y configuration as a radial engine and being used in aircraft, the Anzany three-cylinder engines were state of the art at the time and helped pioneer manned flight.
3-71 Detroit Diesel
This one is probably less “weird” and more, “Huh, I never knew they made that!” Most of you reading this are probably familiar with the 6-71 and 8-71 Detroit diesel engines, whose Roots-style superchargers were made famous by hot-rodders. However the three-cylinder version featured the same 4.50-inch bore and 5.00-inch stroke as it’s larger, more powerful siblings, while offering a compact footprint.
The roughly three-foot cube of an engine weighed in at a stout 1,525 pounds, while producing 109 horsepower at 2,100 rpm and 299 lb-ft of torque at only 1,400 rpm, making it an exceptional tractor powerplant.
While technically the “Nembo 32” is the name of a prototype motorcycle, it’s engine it could be called one of the Stranger Things about the project (you’ll get that bad pun in a second). You see the bike’s air-cooled inline-three-cylinder doesn’t come across as all that odd on paper, until you see that it’s mounted upside down in the chassis.
Making 200 horsepower and 156 lb-ft of torque, the engine is no slouch, and its inverted design really had nothing to do with engine performance, but rather the chassis performance, attempting to centralize as much mass as possible at the center of gravity. While an interesting idea, financially, it was a big-old flop — if you take it’s complete failure to crowd-fund as any measure of its success.
We’ve saved the best (read: weirdest, coolest, rarest, most interesting) three-cylinder engine for last, the Honda MVX250F engine. A two-stroke 90-degree V3 (yes, V3) the engine was designed for the 1983 MotoGP season. Honda has never been afraid of trying weird stuff when it comes to it MotoGP efforts, and this 249cc engine proves it. With a 47mm (1.850-inch) bore and 48mm (1.890-inch) stroke, the tiny engine made 49 horsepower at 9,000 rpm and 23 lb-ft of torque at 8,500 rpm.
While those numbers might seem low, that calculates out to almost 200 horsepower per liter from a naturally aspirated engine with an 8.0:1 compression ratio. Oddly, enough, the single-cylinder engine “bank” was often jetted differently than the two-cylinder bank, which probably exacerbated the engine’s inherent instability, which was attempted to be countered by using a significantly heavier connecting rod on the single-cylinder side. Unfortunately, the engines vibratory nature was hard on components and the bike itself wasn’t a commercial success, relegating the engine to a mere footnote in history.