Triumph TR8 Engine

Road & Track explained in 1980 that the TR8's bore and stroke were just as they had been when Buick built the V8 for its Special and for Oldsmobile's F-85, in the early 1960s; Road Test dated it to the Buick of 1963. General Motors dropped it, and Rover took it on: "Leyland finagled the rights-to-produce out of GM for an undisclosed price in 1965," Car and Driver wrote. By the time the TR8 was built it was Rover's engine, in the SD1 saloon (sedan), and Triumph's own V8, from the Stag, had not been approved for further production; the history tells how the TR8 came to wait for it.

The TR Register lists the larger sizes it grew to, 3.9, 4.0, 4.2 and 4.6 litres, and an Australian version of 4.4 litres with a longer stroke and a taller block.⁠source 1​source 4​source 5​source 6​source 7

Jaguar Rover Triumph's brochure of 1980 describes a 90° V8 with overhead valves, an aluminium block with cast-iron dry liners and a crankshaft in five main bearings, and Motor Trend adds hydraulic valve lifters. Its ignition was electronic, with its amplifier inside the distributor, a known weak point that the buyers guide explains. On most cars the coil sits above the radiator, though triumphtr8.com finds the SD1's ignition, on the inner wing (inner fender), on some late and personal-export cars.

For America it came in two forms. The 49-state engine of the 1980 model year used a pair of Zenith-Stromberg carburettors, under airboxes made for the TR8 alone. California's had Lucas/Bosch L-Jetronic injection: a Bosch air-flow meter, injectors, a cold-start injector, a thermo-time switch and an auxiliary air valve, run by a Lucas control unit, with a three-way catalyst and an oxygen sensor in the exhaust. Michael Lamm noticed at the launch that the TR8's injection plenum faced the passenger's side, where the Rover 3500's faced the driver's. Every North American engine of the 1981 model year was injected, and James TenCate traces the number of injected TR8s, the California cars of 1980 among them, to Canley's first order with Lucas for the injection systems. Many TR8s had two electric fans as well as the engine-driven one.

The testers liked the sound as much as the pull. Road & Track heard "a light, faraway burble" at start-up, and Motor Trend wrote that "Just the way it sounds is enough to make you want to head for the nearest stoplight to lay in ambush for some unsuspecting Porsche". The specifications give the ratings, which are disputed for the injected engine.⁠source 8​source 2​source 1​source 9​source 10​source 11​source 12​source 6​source 13​source 14

Each TR8 engine number begins with a prefix ending in E that gives its market, its fuel system and its gearbox: 10E to 15E for the American engines, from the 49-state carburettor engine to the injected one, and 20E or 21E for the British cars. Many test and development engines carry 13E, and some EXP. Identification sets out every prefix, and explains why an engine number alone proves nothing about the car.⁠source 15​source 10

For the British TR8, BL Motorsport at Abingdon tried a different engine and chassis on the development car NWK 988W in 1980. Richard Hurdwell's memo of 16 December describes the engine work: SD1 pistons to raise the compression, a new camshaft, and a carburettor needle to suit it:

According to triumphtr8.com, citing John Davenport, BL Motorsport's director, the WL9 camshaft was developed by the competition department and fitted to about 20 company cars, and was later homologated for the racing Rover Vitesse, but it never went into a production engine. The British TR8 itself was dropped before it went on sale.⁠source 16​source 9

Group 44's TR8 won its class in its first race, in 1979, and Ken Slagle took the SCCA's C Production title in 1981; racing and Group 44's TR8s give the results. The works rally cars of BL Motorsport, TR7 V8s on the TR8's recognition, ran Rover V8s too, and their story belongs to the TR7.⁠source 17​source 6​source 18