The 500-horsepower flat-six is just the beginning of the collaboration between Singer and Williams.

California-based Singer Vehicle Design and Williams Advanced Engineering have teamed up to develop a modern version of Porsche's air-cooled flat-six engine.

The two partners brought in Hans Mezger, the 87-year old engineer who designed the original Porsche flat-six for the 911, as a technical consultant. They created a 4.0-liter air-cooled engine that makes 500 horsepower without resorting to forced induction.

The torque output hasn't been released yet, but we know the six-cylinder is capable of revving beyond 9,000 rpm. Dual oil circuits and a bigger cooling fan keep the temperature in check.

Since saving weight was a priority, the engine uses titanium connecting rods, aluminum throttle bodies, and carbon fiber trumpets. The air box is also made out of carbon fiber. Every part of the engine looks like a work of art, which falls in line with Singer's philosophy.

"Having had the opportunity to consult with Hans Mezger - the "father" of the iconic air-cooled flat-six - about the development of the engine, our team was pleased to be able to provide a solution to Singer's clients' requirements and of course, to be a part of this iconic vehicle's continued evolution," said Paul McNamara, Williams Advanced Engineering's technical director.

The engine was commissioned by a customer whose 911 is undergoing the Singer treatment. Full specifications will be announced when the car is unveiled next month. At least two additional engines will be built in the coming months, and there could be more.

Singer and Williams pledged to continue their partnership in a bid to make classic 911s lighter and more dynamic to drive.