The Chrysler Slant-6 engines used in the Plymouth Valiant and Dodge Dart A-body models of the 1960s and 1970s featured a 30° inclined design to achieve a lower overall height. Originally designed to be built of aluminum, but after encountering problems in manufacturing the engines in aluminum, they were built in cast iron without changing the design to compensate for the stronger metal. Although it only had four crankshaft main bearings instead of the seven used by its competitors, they were the same size as those on the Hemi V8. The Slant-6 achieved some success in racing when engineers utilized the slant of the engine for very long intake manifold passages to boost horsepower by tuning the intake system. After 30 years of production, it was discontinued in favor of V6 engines because it was too long to mount transversely in front-wheel-drive cars.