BOXING TOO CLEVER
The flat-four engine envisaged for the Minor was conceived in two capacities – 800cc and 1100cc – and was a cast-iron sidevalve unit. But why a flatfour? A horizontally opposed engine is smoother and better-balanced than an in-line unit, but a more fundamental advantage is compactness. Because the engine is shorter, the crankshaft and crankcase are more rigid, plus the engine isn’t as tall so the centre of gravity is lower.
Every bit as valuable is that a compact engine takes up less space in the vehicle, and for Minor creator Alec Issigonis few things mattered more. The engine was indeed small – 13in from crank pulley to flywheel – and narrow, thanks to its old-fashioned sidevalve configuration, chosen by Issigonis for precisely that reason.
By September 1945, the original ’43 prototype had been fitted with the first experimental flatfour, which, evidence suggests, was of 800cc. Subsequently an 1100cc unit arrived and was tried in another pre-production car.
Surviving engineering drawings from 1946 depict two different versions of the 800cc engine, one called YF80M and the other ZF80M. The ZF80M is a dry-sump design with a separate oil tank, one pump to distribute oil to the bearings and a second ‘scavenge’ pump to return it to the tank. This expensive solution makes the engine less tall, for a still lower centre of gravity. It appears that at least one dry-sump flat-four was tested in the ‘Mosquito’ prototype, but it’s hard to imagine the Morris accountants being enthusiastic about such elaborate engineering.
YF80M is a more orthodox wet-sump design. As with the dry-sump engine, it had two main bearings. With the shorter crank of a flat-four this isn’t necessarily a disadvantage if the mains are sufficiently beefy – and to add a centre bearing would increase the engine’s length. According to Jack Daniels, right-hand man to Issigonis, the crank had generously proportioned main bearings and never gave any problems.
The engines acquitted themselves well, according to Daniels. “We tested mainly the 1100, and that gave reasonable performance – much better than the Morris Eight engine,” he said. “It was pretty good. You were conscious of a flat-four exhaust beat – a bit off-key and different from any other engine – but you got used to it.”
Former Morris Engines employee Fred Collis remembered his father driving a prototype with the flat-four from Coventry to Cowley. “He said the car was marvellous and had far more speed than a Morris Eight,” he recalled. “He was very impressed by the performance.”
One-time Nuffield engineer Jim Lambert’s recollection was less rosy, but he was in his early 20s then and all he knew about the flat-four was secondhand. “I don’t think it had a chance,” he said. “It was gutless and wasn’t any real advance on what we had. It wasn’t a big step forward.”
The experimental engines did have vibration problems, apparently caused by a poorly located flywheel. Former Morris Engines employee John Barker recalled other failings: “Engineers in the experimental department said it died a death because of bearing trouble – the bearings were too noisy. I was told there was crankshaft whip, I believe because with only two main bearings there wasn’t enough support for the crank.”
Any tendency for the crankshaft to whip in extreme circumstances would have been exacerbated by vibrations from an out-of-true or loose flywheel. Such development problems would normally be ironed out quickly, had time, resources and management goodwill allowed.
It wasn’t that simple, though. The flat-four was going to be expensive to produce. In July 1947 it was calculated that the YF80M and its fourspeed column-change gearbox would have cost just over £47 to manufacture; the Morris Eight engine and gearbox was costed at £38, making the boxer unit a whacking 24% costlier.
Worse, from Morris Engines’ perspective, it ‘wasn’t invented here’. The division was struggling to put a family of in-line engines into production, including the 1000cc and 1100cc ‘fours’ it saw being used in the Mosquito and any spin-offs. It can only have seen Issigonis’s flatfour as a cuckoo in an overcrowded nest.
Development of the flat-four dragged on too long. In June 1946 it was expected the engine would be in production before mid-’47, yet in April that year there were still concerns about the vibration problem, while the bigger unit for the Oxford still hadn’t made it off the drawing board.
More fundamentally, the Nuffield Organization’s management and Lord Nuffield himself weren’t even sure about bringing the Mosquito to production; its radical design evidently frightened them. In a maelstrom of decisions and counter-decisions, consideration was given to cancelling the car in favour of an updated Morris Eight Series E, or at best making it in small numbers with an MG badge. The thought of an all-new flat-four must have had tired managers reaching for the smelling salts.
The final blow came in June 1947 at a Morris board meeting. Citing the arrival of a flat rate of road tax in place of the RAC horsepower system, the flat-four engine programme was abandoned; in October, the Mosquito was at last given the green light and pushed towards an end-of-1948 introduction, ultimately with a conventional in-line sidevalve engine. Logic, fed by internal pressure from Morris Engines, had prevailed.