Porsche just took the covers off its turbocharged 4-cylinder engine that was behind the Le Mans-winning 919 hybrid.

And it is beautiful!

But first, consider the entire drive concept. The turbo-4 drives the rear axle. Then there’s an exhaust recovery system tied to the latest lithium-ion battery technology to serve an e-machine on the front axle where additional power is drawn from braking.

Porsche released four photos but not a lot of information about the compact powerplant. Stuttgart says the 2.0-liter engine is the most efficient combustion engine Porsche has ever built. Some of this technology goes into the 718 Boxster, such as interspace between cylinders, short-stroke and central direct fuel injection.

“Right from the beginning we had a brave concept, but it was also the right concept. This is paying off now,” says Alexander Hitzinger, technical director for the 919.

Unlike the Boxster with its flat engine profile, the 919’s engine is a 90-degree V4. It was putting out over 500 horsepower last year, but new fuel regs for the prototypes reduced fuel flow by eight percent, resulting in a slight loss of power. However, combined with the electrical energy from the brake and exhaust recovery systems, Porsche says the 919 Hybrid’s overall power is about 900 horsepower.

Porsche says it returned to World Endurance Championship (WEC) racing because innovations in the class have a major impact on production sports cars. Regulations for Le Mans prototypes (LMP1) require manufacturers to use hybrid drive systems. They also establish a direct link between performance and energy efficiency, allowing a large amount of energy from recovery systems. However, this entails a proportional reduction in the permitted amount of fuel per lap.

WEC says teams can choose between diesel and petrol engines, naturally aspirated or turbocharged engines, various displacements, and one or two energy recovery systems. Hence, the eventual relationship between racing and production.