Triumph Slant-4 engine

The Triumph slant-four 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 Dawtrey 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, for use in their new 99 model. When that development proved too expensive and risky to produce, Ricardo, knowing the slant-four was almost ready for production, brought Saab into contact with Triumph.

Saab first used the Triumph slant-four 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-four 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 added unique SOHC four-valve cylinder heads to the slant-four for 1973's Dolomite Sprint. A team of engineers led by Charles Spencer (Spen) King developed the 16-valve cylinder head with all of the valves being actuated using a single camshaft rather than the more conventional DOHC arrangement. The capacity was also increased to 1,998 cc (122 cu in), and combined with bigger carburettors the output was raised to 127 bhp (95 kW). This represented a significant increase over the smaller 1850cc variant, however it fell short of the original target of 135 bhp (101 kW).

...
Wikipedia