The Slant 6 Chrysler engine was developed in the late 1950s in the USA as a 170 cubic-inch powerplant for the 1960 Plymouth Valiant and Dodge Lancer. Late in the development process it was decided to build a larger-capacity version of the engine for use in larger Chrysler vehicles, as a replacement for the ancient flathead 6-cylinder currently being used. The 225 cubic-inch version used a longer stroke with the same head, pistons and connecting rods. This required a taller cylinder block casting to compensate. Later, a 2bbl version was added for marine and export markets, and a 198 cubic-inch variant was introduced as well. Later U.S. market slant 6 engines featured improvements like alloy intake manifolds and hydraulic lifters.
Originally conceived as an all-aluminum engine, the slant 6 was engineered with thick cylinder walls and a tough skirted block. While some aluminum engines were produced in the first few years of production, they were troublesome. Primitive casting technology at Chrysler and the unwillingness of buyers to pay more for the benefits of an aluminum engine doomed the aluminum slant 6 after 1962.
The heavy block casting would prove to be an asset for the iron block engine, however. With huge main bearings (shared with the B engine V8) and thick cylinders, the slant 6 gained a reputation as one of the toughest engines ever built, by any manufacturer. In particular, the 225 with its comparatively small ports and valves was a low revving high torque engine that eventually powered everything from cars to medium-duty trucks, power boats and industrial equipment.
The slant 6 was one of Chrysler’s most-exported engines, with thousands built in local factories as well. While it was never intended as a high-performance engine, the slant 6 was raced with factory support briefly in NASCAR’s short-lived compact series during the early 1960s. A number of importer-sponsored and privateer racers built slant 6 powered racers over the years, in the United States, Australia, Argentina and South Africa.
Today the slant 6 is enjoying a resurgence in popularity and attention as a high-performance engine. While it may never compete with a V8 engine on dollars per horsepower, it makes an attractive choice for a period-modified car, or a dare-to-be-different hot rod. Thanks to new parts sources in Australia and the U.S., more manifolds, headers and internal engine parts are available now than at any time in the recent past. That makes it even easier to pick a slant 6 as a street performance choice.