Concepts : Rover P7
The missing link
ALTHOUGH the Rover P6 had been launched to ecstatic reviews in late-1963, the main gripe the media had about the car was the lack of refinement from its 1978cc four-cylinder engine. Existing Rover models such as the P4 and P5 had smoother six-cylinder engines, as indeed did the cars from Coventry upstart, Jaguar. More seriously, the Triumph 2000 which was directly aimed at the same market sector as the P6 could also outgun the P6 in the silkiness stakes.
In addition to this problem, Rover faced the more serious conundrum of developing new lighter engines to replace the 2.6- and 3-litre IOE units used in the P4 and P5 saloons. Rover’s sales department had wanted the P6 to have a six-cylinder engine from the outset, and so in 1962, and before the P6’s official launch, Jack Swaine’s engine department began to investigate a number of possibilities.
The logical thing to do was to build a six-cylinder version of the modern P6 four-cylinder engine. Using the same bore and stroke as the four-cylinder produced a swept volume of 2967cc. The six-cylinder engine certainly produced the required grunt but was 50 per cent longer, which according to James Taylor’s 1996 book Classic Rovers 1946-1986 required a longer nose for the P6 test beds.
The extended nose resulted in the model receiving a new factory code, P7. However according to legendary Rover engineer Spen King in his 2002 interview with Keith Adams. “The six-cylinder engine would go into the P6 bodyshell, not just as a P7, which was never considered for production seriously at all. The P7 was purely a development thing. But there was something that we called P7A, which was no longer than the P6 and had the six-cylinder engine in, and double wishbone suspension…To say that it would not go into the car was wrong. In P7, it stuck its nose out and was too heavy and everything.”
Spen King on the P7A
‘It’s not a bad motorcar, that engine was a pretty good engine actually. That was too heavy somehow. In other words, if you make a four into a six, you oughtn’t to have to make it fifty per cent heavier because a lot of the stuff there is the same as the four-cylinder. But in fact, somehow or another, it got a very heavy sump or something, and it made the engine very heavy.
‘I batted very hard against the V8 to try and continue that because I believe the BMW policy was right; if you’ve got something, you ought to develop it – that way you have a linear development programme instead of hopping over here and there – doing something completely different. But I was wrong I think… No doubt that V8 was a huge asset.’
According to James Taylor, the P7A came close to production; the cost in new body tooling prohibited the final go-ahead. Had the P7A gone into production it would have been called the Rover 3000 to avoid confusion with the existing Rover 3-Litre. This resulted in the smaller engined P6 being christened the Rover 2000 instead of Rover 2-Litre.
Instead, in 1964 Chief Engineer Robert Boyle suggested the company develop a five-cylinder variant of the P6’s 1978cc four-pot. The resulting engine had a swept volume of 2472cc, and presented Rover engineers with the problem of in-car balance.
Spen King’s take on events and the origins of the five-cylinder engine are as follows: “I think it came mostly out of Brian Sylvester, who was head of research. It was a pretty sensible idea. The problem was that you hadn’t got fuel injection then – you need fuel injection to make five-cylinders work, because the carburetion is a bit of a mess… I mean the obvious way is doing it with an injected version, and this prototype was built with carburettors.”
Fortunately for Rover, the company’s Managing Director, William Martin-Hurst, had stumbled across a discarded light alloy General Motors V8 while on a visit to the USA in 1963. The engine was compact, powerful, reliable and just what Rover needed. Rover bought the rights to manufacture this engine, cancelled the various P7 projects, and was now able to move forwards convincingly.
The V8 engined P5B appeared in 1967, and was followed in April 1968 by the V8 P6B, now known as the Rover 3500. Could the Range Rover have happened with a 2967cc inline six-cylinder engine?
Rover’s attempt to build a new engine on the cheap was over and a motoring legend was born.