Nobody does Porsche 911 restomods better than Singer Vehicle Design, but the Californian company has outdone itself with its latest project. Singer has announced that it's teaming up with famed F1 engineering experts Williams to work on a modified air-cooled, 4.0-liter naturally aspirated flat-six Porsche 911 engine that produces 500 horsepower. Yes, that's the same power output as the current 911 GT3 RS. The project was commissioned by Scott Blattner, a regular client of Singer, and the engine will be installed in Blattner's 1990 Porsche 911.

Singer and Williams even enlisted the help of Hans Mezger, who designed Porsche's first flat-six, as a technical consultant for the project. Based on a 3.6-liter flat-six originally designed by Mezger from a 1990 Porsche 911, the modified unit expands the capacity to four liters and uses four-valve cylinder heads, dual oil circuits, titanium connecting rods, aluminum throttle bodies, carbon fiber intake trumpets, and a carbon fiber air box. Ram-air intakes have been built into the 911's rear quarter windows, and a titanium and Inconel exhaust has also been fitted. With these modifications, the engine will now rev up to 9,000 rpm which must sound sublime.

Singer is delighted to be working with Williams Advanced Engineering and Hans Mezger to offer our clients a 'next level' of restoration and modification services for their Porsche 911s," said Singer's founder Rob Dickinson. "With careful and dedicated development, this iconic air-cooled engine has much to give both its existing devotees and a generation of new enthusiasts." Other details are being kept under wraps for now, but the finished project will be revealed in September.