A 16-cylinder engine is wild, but with a boxer configuration, it's simply unheard of.
Porsche's legendary 917 race cars were not made overnight; the German marque had to undergo years of development, including creating a 16-cylinder engine.
In the early 1970s, Porsche faced a formidable challenge in the Can-Am series dominated by McLaren despite the success of Porsche's 917 in endurance racing.
In the Can-Am series, the 917/10 initially struggled with a power deficit against V8-powered competitors, so Porsche explored addressing power challenges by developing a flat 16-cylinder engine capable of over 800 horsepower. Serving as a test mule, the 917 PA Spyder featured the unique motor developed by the legendary Hans Mezger under Ferdinand Piech's supervision.
Inspired by the 912's 12-cylinder design, the 16-pot mill had centrally driven camshafts and scalable displacement from 6.0 to 7.2 liters. The largest 7.2-liter variant produced an impressive 880 hp, or twice the power a base Porsche 911 makes from the factory.
The flat-16 engine featured canted inlet valves and a Bosch fuel injection system. While only four complete engines were manufactured, the possibility of producing parts for up to ten engines existed. Despite ample horsepower, the flat-16 engine couldn't match the scalability of turbocharged cars, leading to the decision to adopt boost.
The decision proved right, as subsequent turbocharged Porsches born from this development found immense success. They were, after all, the most powerful racecars of the day. Today, only one 16-cylinder prototype remains in the hands of the German marque.
Ultimately, Porsche chose to turbocharge the 12-cylinder engine, resulting in the iconic 917/30 dominating the series with over 1,100 hp. It was the most powerful race car of its time (and among the most expensive Porsches today), reaching speeds of 221 mph at the Talladega Superspeedway. Much like the original R23 Nissan Skyline GT-R, the 917/30's success prompted rule modifications and limitations regarding fuel consumption.
This wasn't the only unusual boxer engine Porsche made. A 750-hp flat-eight was once earmarked for the 918 Spyder replacement, and although it found a home in a wild concept, it never made production. Imagine what racetracks might sound like today if Porsche had developed all its possible iterations of the horizontally opposed engine.