[StevoRocket]

Imp or Stilleto- 875cc made by Rootes Group in UK, rear engine, sideways - lots of aluminium, block and head. Overhead cam.

Head-on, the Imp looks like a miniature early series Corvair. The resemblance is more than coincidental. While Rootes stylists were borrowing contours from the Corvair body, Rootes engineers were test-driving Corvairs, looking for technical solutions to rear engine design problems. Unlike their counterparts in the styling department, the engineers didn't copy the Corvair so readily. After crashing one 'Vair rather severely at the test track, Rootes rejected swing axles and adopted a fully articulated multi-link rear suspension for the Imp. And, to minimize rearward weight bias, the Rootes engineering staff insisted on a lightweight all-aluminum engine.

And what an engine it was! For the basic layout, Rootes engineers called upon Coventry Climax, one of the most renowned engine designers in the world. Coventry Climax engines powered some of that period's most successful Formula 1 cars, including the Lotus 18 and the Cooper T51. Coventry Climax was eager to capitalize on its racing success and sold Rootes the production rights to a state of the art overhead cam 750 cc four cylinder engine. Rootes proceeded to modify the design to make it suitable for the Imp by opening it up to 875 cc, laying it over on a 45 degree angle, increasing the compression ratio to 10:1, and die-casting the block and head in aluminum.