The Morgan Plus 8 is a sports car built by British car makers Morgan between 1968 and 2004. Its instant and enduring popularity has been credited with saving the company and keeping the company famous during the 36 years of its manufacture. Among Morgan enthusiasts, it is deeply associated with Peter Morgan, the owner-chairman behind its design.
The development of the Plus 8 was led by Maurice Owen, a race car engineer taken on specifically for the role. The Plus 8 prototype was based on a modified version the chassis of the Plus 4, to which it added the Rover alloy block 215 cu in (3.5 l) V8, purchased from GM-Buick in 1967. Plus 4's Moss gearbox was carried over and the Salisbury 7HA axle was uprated with a limited slip differential. The chassis was developed in stages to accommodate gearbox changes in 1973 and 1976, the body widened in 1976 to accommodate the widened chassis and the wings widened to accommodate larger tyres to handle the increasing power and trend for lower profile and wider tyres. The original 1968 Plus 8 was 57 inches (1,400 mm) wide and the last was 64 inches (1,600 mm) (with an optional "widebody" at 67 inches (1,700 mm)) For several years in the 1960s the Plus Eight was the fastest-accelerating UK production car.
To mark the 35th year of production of its Plus 8, MMC released a commemorative 'Anniversary Edition'.
All Plus 8s engines were based on the Rover V8 which had been bought by Rover. Morgan was the first of a succession of sports car makers- including the likes of TVR and Marcos- to use the engine, which Rover had only just made available in the P5B saloon.
The Plus 8 development car used a Rover V8 block and the Plus 8 was launched in 1968 using Rover's production engine, itself a re-engineered version of the Buick 215 block (renamed the 3.5 L by Rover) with a compression of 10.5:1 fueled by two SU HS6 carburettors. By 1973, the Rover 3500 saloon was available with a manual 4 speed gearbox and this engine/gearbox configuration was adopted by Morgan although the compression dropped to 9.25:1 with a resulting loss of power. With the adoption of an improved version of the block developed for the Rover SD1 in 1977, compression was increased to 9.35:1 and power increased. After 1981 the engine was fueled by two Stromberg carburettors, .
At the end of 1983, the company offered a EFI version using a Bosch L-Jetronic based system. With the added power (204 bhp (152 kW; 207 PS)) and low weight, the Plus 8 was, according to the magazine road tests of the day, able to best a Porsche up to 90 mph (140 km/h). In 1990, a 3.9 L version of the block was added using the Lucas 14CUX fuel injection system.
In 1996, a 4.6 L version found its way into the car as an option, still using the 14CUX system. From 2000, all Morgan Plus 8s were fueled by the GEMS system used on the Land Rover Discovery II.