4. The Boffin and his 3 failed engine projects
In 1964 Stokes recruited Dr Albert Fogg to be director of research. Previously head of M.I.R.A, he had an impressive CV and was seen as an engineer who would think “outside the box”. In the words of the chairman he was to “bridge the gap between the rapid advance in scientific knowledge and the practical application of that knowledge by the industrial engineer”. It was a powerful new position. He rightly acknowledged the trend towards more powerful truck engines – prompted in part by changes to gross vehicle weights in the UK and Europe but it was his radical “blue-sky” approach that contributed significantly to Leyland’s demise.
Rather than progressive development of existing engines with turbo-charging, Fogg advocated development of a revolutionary pair of diesel engines to be known as the O.500 and O.700. They shared the distinction of eliminating cylinder head gaskets by having a combined cylinder block and head castings. The design also featured an overhead cam. Blowing gaskets had not been a big issue previously but was envisaged as a potential problem if turbo-charging was to deliver sufficiently higher cylinder pressures.
The O.700 plans were quickly dropped when the first prototype showed that the overall height of the engine was too great to be fitted under the new Ergomatic cab. Rapid development of the O.500 continued and a completely new production facility was commissioned ready for its production at a cost of around £100m. Manufacturing output from the new automated machine tools was plagued with technical issues giving rise to 35% failure rate on the production line alone. In service the engine suffered major structural failures and to compound matters it was time-consuming to repair and maintain. Production had to be discontinued.
This drove Fogg to look around for an expedient but instead of fitting turbos an existing and proven engine, he resurrected an earlier still-born project for a compact V8 designed at AEC. Whilst the V8 had been shelved in the face of problems during development, AEC had already purchased the machine tools for its production. This gives a clue as to how bad it really was.
This V8 was an over square design and, as such, characteristically needed to be run at relatively higher speeds to achieve a given horsepower. Whilst it was lightweight, like all over-square V8’s it had high fuel consumption, noise and emission levels despite comments to the contrary in the relevant press release.
At its release in 1966, Mr. D. K. Roberts, chief engineer and a director of AEC extolled the virtues of the V8 saying ”the strict enforcement of weight regulations would favour a lightweight engine, one having a good low speed torque output that could give an acceptable performance when mated to a five or six-ratio gearbox.””
In reality, an over square engine has poor low speed torque and performs best only when coupled to a gearbox with between 9 and 15 ratios.
He went on to say that a competitor’s patents “had covered the best cylinder bore to stroke ratios so the choice was either a long stroke “V” engine or a squat over-square “V” engine”
In reality no manufacturer can patent dimensions or ratios so this is a limp excuse for the choice of an over-square design. Over-square designs have predominately been failures. Just ask ■■■■■■■■ Roberts failed to say why they did not choose a long stroke which would have given better torque and lower revs. Trucking history is littered with failed over-squares whereas the most successful V engines have all been under-square e.g. Mercedes Benz Scania.
In service the V8 was a design disaster. One even failed catastrophically on an early Commercial Motor magazine road test! Amongst an extensive list of defects it had a tendency to pull the cylinder liners down into the sump which brought about complete self-destruction. For the better ones which did not self-destroy, the big-end bearings were doomed to failure around 50,000 miles. The result was increased warranty costs and further erosion of customer confidence. It also compelled Leyland and AEC to go to the likes of ■■■■■■■■ Rolls Royce, Gardner and DAF for high horsepower engines and drove truckers to imported marques.
Engine calamity number three was the gas turbine design with links to the days of Sir Frank Whittle acquired from Rover after the take over by Leyland in 1967. Dr Fogg espoused his vision of installing it in some heavy truck models. Whilst it never went into series production it did consume considerable development and financial resources over a number of years.
The failure of these three engine projects meant that 7 years were lost until a turbo version of the AV760 came out in 1974 as the TL12 in the Marathon. By then even that was underpowered against the latest competitors. Furthermore the economies of scale to be achieved through rationalisation were never realised.
The saddest part is the missed opportunity of developing the venerable Leyland O.680 engine. The design was licensed to DAF who bored it out by a modest 3mm, turbocharged it and tidied up a few minor items. The result is a major success that is still in available today turning out more than twice the original horsepower. Had Leyland achieved the same, it would have reaped massive economies of scale by standardising this engine across the Leyland, AEC, Scammel, Guy, Daimler heavy truck and bus model ranges.