Ward’s 10 Best Engines competition has recognized outstanding powertrain development for 20 years. This installment of the 2014 Behind the 10 Best Engines series looks at the history and development of Porsche’s thrilling H-6 boxer.

Just as only two major automakers today, General Motors and Chrysler, still proudly build and market cam-in-block (pushrod) V-8 engines, just two, Porsche and Fuji Heavy Industries (Subaru), proudly offer flat, horizontally opposed "boxer" engines.

Chrysler's powerful Hemi V-8s and GM's small-block family continue to enjoy strong reputations and sales, and so do Porsche's flat 6-cyl. engines and Subaru's versatile H-4 and H-6 powerplants.

Subaru has used front-mounted boxer engines since its early years. Porsche has installed high-performing flat 6-cyl. engines in the rear of its 911 sports cars for half a century and counting. The German automaker also has situated its boxer engines between the axles in smaller, more affordable ’69 to ’76 model year 914 models and more recently in Boxster roadster and Cayman coupe 2-seaters.

Porsche also built H-4s for its original rear-engine 956 sports cars, early entry-level 911s (which were badged 912s) and base mid-engine 914s and even a small-displacement boxer 8-cyl. for a few rare 904 race cars.

And it now builds powerful, sophisticated V-6s and V-8s for its sedans and SUVs. But the iconic flat-6 lives on at Porsche, and 50 years after debuting in mid-1960s 911s, it keeps getting better and more refined.

Flat horizontally opposed piston engines date back more than 100 years and have been used in everything from lightweight aircraft to motorcycles. They still are popular on current BMW and Honda 2-wheelers, in part because they have some inherent advantages over inline and “V” configurations, including good natural balance and low centers of gravity. But Subaru admits they can be more expensive and require different transmissions compared with transversely mounted inline engines.

From a packaging standpoint, boxers are lower but much wider than inline engines, which (combined with their low center of gravity) makes them ideal for Porsche's rear- and mid-engine sports cars (not to mention decades of now-extinct H-4-powered rear-engine Volkswagen Beetles). And this latest 275-hp Porsche 2.7L 6-cyl. boxer, which is standard and not an up-power option in ’14 Boxsters and Caymans, is one of the sweetest yet.

Porsche says the manual-transmission Cayman can sprint from zero to 60 mph (97 km/h) in a swift 5.4 seconds, while the PDK-equipped 2.7L Cayman is a tenth of a second quicker at 5.3 sec. and quicker-still at 5.1 sec. with an optional Sport Chrono package. After testing it in a ’14 6-speed manual Cayman, WardsAuto editors called it "a perfect match" for that lightweight coupe.

Its 213 lb.-ft. (289 Nm) of peak torque @ 4,500-6,500 rpm is fairly meager by today's standards, they point out. "But engage the starter, and it becomes obvious why the new flat-6 has won Porsche's fourth Ward's 10 Best Engines trophy. Put the 2,888-lb. (1,310-kg) coupe into gear, let the engine work a little more of its aural magic, take it for a short ride through the twisties, and the point about minimizing weight while maximizing power becomes crystal clear."