Triumph Slant-4 engine

The Triumph Slant-4 is an engine developed by Triumph. According to Triumph historians Graham Robson and Richard Langworth in "Triumph Cars, the complete story", the engine was developed in-house by a design team led by Lewis Dawtry and Harry Webster.

The UK engineering and consultancy company Ricardo, which did have a general engine-development contract with Triumph, was not directly involved with its design, but was usually kept informed of anything new being planned. Ricardo was involved in developing a new engine for Saab, as a replacement for their aging Saab two-stroke and V4 units. When that development proved too expensive and risky to produce, Ricardo, knowing the slant-4 was almost ready for production, brought Saab into contact with Triumph.

Saab first used the Triumph Slant-4 at 1.7 L (1709 cc) for the Saab 99. Only later, as production capacity increased, did it become available in Triumphs. Development by Saab continued into the 1990s. The engine is a straight-4 with the cylinders tilted at 45 degrees (actually in effect half of the Triumph V8 that was used in the Triumph Stag).

The engine was used by Triumph in the Dolomite 1850, the Dolomite Sprint, and the TR7. It was also used by Panther in the Dolomite-based Rio (1975-1977). Triumph ended manufacture of the engine when the TR7 was discontinued in 1981.

Triumph Sprint

Triumph Motor Company added unique SOHC 4-valve cylinder heads to the Slant-4 for 1973's Dolomite Sprint. This is regarded as the first mass-produced multi-valve engine.

aab B engine

Saab later increased the engine size to 1.85 L and in 1972 the company brought production in-house (to Scania) for the 2.0 L B version. This engine shared much with the original Triumph design, including bore centers and bearings, but was substantially redesigned. The Saab B engine was replaced by the related Saab H engine.