A Peugeot Talbot Motor Company hand-out citing the Peugeot 205 Diesel, which was launched in 1983, as the best-selling diesel-engined car in Britian, with 88,200 sold over the nine years of its existence, and claiming a fuel thirst of 72.4mpg from this lively little oil-burner, sparked off a recollection of pioneering by Peugeot in this field.
As far back as early 1923 the Peugeot engineers were ready to publicise comparisons between petrol and oil-engined cars. This is all the more remarkable when it is remembered that in 1950 Motor Sport was quite excited that David Scott-Moncrieff, who was in Germany, was able to provide us with a road test report on a small Mercedes-Benz saloon powered with a diesel engine. He headed his article “D for Diesel Day”, and at the time this proclaimed a revolutionary development to which other manufacturers might eventually turn, but not, it was considered, for a long time to come.
Yet Peugeot was working towards these lines 28 years earlier… Their comparison demonstration, observed by a delegate of the AC de France, was between two virtually identical cars, both the well-liked and high-grade 15hp Colonel model, which sold in Great Britain (let’s include “Great” to cheer us up in these difficult times!) for £640 as a chassis. But whereas one had the four-cylinder 85 x 130mm (2951 cc) petrol engine, the other Peugeot had a two-cylinder two-stroke 100 x 140mm (2199cc) Tartrais-type “gas-oil” engine. Both Peugeots had what were described as six-passenger open touring bodies, although I would have thought that this implied sitting in close proximity, which is perhaps a French characteristic. To make the petrol/diesel comparison fair, both cars had final-drive ratios of 4.58 to 1, and ran on 880 x 120mm tyres — Michelin of course. The respective weights were 31 cwt 2Ib and 31cwt 1061b. But it was estimated that the heavy tool kit brought along by a mechanic accompanying the oil-engined car increased the weight of this one. After four passengers had got into each car (four, not six, note), the weights were adjusted to 37cwt 57Ib and 37cwt 45Ib respectively, the diesel Peugeot having the slightly lighter crew.
The petrol Peugeot had the usual Zenith carburettor on the off-side of the side-valve engine, fed by Autovac, and the normal transversely-driven SEV magneto. The Tartrais two-stroke oil engine had fairly normal cast-iron cylinders, but special cylinder heads with two rings of ports, one for inlet, the other for exhaust. A low-pressure compressor driven from the crankshaft fed air into the cylinders, driving out the spent gases via the upper ring of ports. Vaporised fuel was injected into the cylinders. Nor was that all, because as the piston got close to the top of the head it forced the air into a special ring-shaped combustion chamber, into which the fuel was injected. The shape of the deflector, and especially the form of the combustion-chamber and the fact that air was forced upwards into it, whereas the fuel was injected horizontally, gave a very high degree of turbulence. It was this that enabled the Tartrais engine to run on so many different fuels — crude mineral oil, vegetable and animal oil, cotton-seed oil, even coco and castor and cod-liver oil. The war having not long concluded, the claim was naturally made that such an engine could dispense with imported petrol.
The combustion chambers were uncooled, made of chrome nickel steel, and able to expand and contract as they were not solidly bolted to the barrels. External bronze castings were bolted to the cylinder barrels, air passages providing cooling while maintaining the very high temperatures of the inner heads. The fuel injection pumps used variable-stroke pistons to control engine speed by hand lever and accelerator, one pump feeding one cylinder. It was claimed this gave nicer control than with a four-stroke, and that “conking out” on hills was avoided. Ignition was self-obtained on the diesel principle, with a sparking plug to warm things up from cold, perhaps with an initial supply of petrol. In 1922 these engines were being experimented with in three Paris ‘buses, in twin-cylinder 120 x 150 mm size, giving 25 bhp at 1200 rpm. Peugeot had commenced trials with a 3393 cc version, developing 50 bhp, also at a modest 1200 rpm, for a weight/power ratio of only 11 lb/hp.
Very soon they were ready to demonstrate the smaller 2.2-litre Tarttrais engine in their 15 hp car, as aforesaid. The day before the trial, both cars were locked away, fuel (both heavy oil and petrol) being checked for density at 15°C. The radiators were filled with cold water (but the diesel car had a radiator muff), the cars were weighed, the passengers, including the famous 46-year-old motoring and aviation journalist W F Bradley — he had been The Motor’s continental correspondent until 1919, then worked in this capacity for The Autocar until 1956 — climbed aboard, the weights were checked again, and the signal given for the electric starters to be operated. The petrol Peugeot fired in 35sec, the diesel car in 45sec but on only one cylinder, so it was stopped and restarted ; total time 67sec. It had been started on petrol but was changed over to oil after three or four minutes, without stopping. Peugeot engineers drove the cars.
To summarise the tests, the diesel car ran down to 5.9 mph, the petrol could only manage 6.17 mph. In a short hill-climbing comparison the diesel Peugeot was slower by eight seconds, and 8.32 mph slower over a public road f s kilo, where the petrol car got up to 45.48 mph. (Even good cars were slower then!) There were a few more not enormously convincing timed tests. But more significant was that on the 103.15 mile outward run the diesel car kept up the same 32.06 mph average speed as the standard Peugeot. Fuel consumption came out at 19.88 mpg from the heavy-oiler, against 18.87 mpg. The important aspect was the fuel costs which were, respectively, 7/3d and £1.8.2d, in 1920s terms, and at a rate of exchange calculated for the francs used that was regarded as not altogether favourable to the oiler. Up to then the oil engine had been used for stationary power and boats, but had been too heavy for cars. Now Peugeot was considering the Tartrais engines, which they were building themselves, worth investigating, especially for their commercial vehicles. However, I have found no evidence that the Tartrais venture was proceeded with; Peugeot would have had to pay royalties on four of the main engine features and probably were not sufficiently impressed to take up production, preferring to wait until the time was riper, such as in 1959 when the lndenor diesel engines appeared in the 403. Incidentally, in 1922 Peugeot were doing well with the little economy 668 cc Quad, which sold here for £230.
Nor was the long-established French manufacturer slow in supporting other economy events. For instance, in the 1923 Touring Car GP at Tours, run over the GP course, Peugeot ran three 18 hp five-seaters in the appropriate class, headed by Andre Boillot, who also managed the team on the road. For this speed-v-economy race, the petrol allowance was at the rate of 18.8 mpg for the 311 miles. Boillot had as team drivers the brothers Morillon. They came home 1,2,3, Boillot in his yellow waistcoat averaging 51.6 mph and declaring that he had two gallons of fuel left and could have gone faster, had the only class challenger, an Aries, troubled them. Not only that, but in the four-seater class, restricted to 28.3 mpg maximum, Peugeots came home in the first three positions, Cabaillot averaging 43½ mph. These Peugeots had the c r raised to 7 to 1 and special cylinder heads gave a good circulation of water round the equally special sparking plugs. This was definitely a case of trying out a new car in racing, because the Knight-type sleeve-valve 80 x124 mm engines were not then in production, although due at the Paris Salon later that year.
According to Shell Oil UK, whereas ten years ago diesel car UK sales numbered less than 1%, this year they have been running at over 12%. This in spite of 85% of those Shell questioned still thinking diesel engines noisy, 70% that they still smoke, 64% that they are smelly. Well, reverting to that 1923 Peugeot comparison test, it was reported that the petrol Peugeot smoked for the first three miles and when accelerating, whereas the diesel car smoked considerably when starting up but this had stopped within three minutes. As for noise, the difference was described as being very slight, and the smell was rated as not really objectionable, caused no inconvenience “but one could not forget there was a smell”. But that was aeons ago, with a very experimental oiler…
Shell also reminds us that Dr Rudolf Diesel patented his compression-ignition engine back in 1892. The first production diesel cars were those of Mercedes-Benz, with their 2.3-litre 260D, and Hanomag’s 1.9-litre Rekord D, both of 1936. The Mercedes-Benz D S-M wrote up for Motor Sport in 1950 was the 1697 cc 170D, but Britain did not join in with a c i private car until 1954, with the Phase II Standard Vanguard.
It is gratifying that Peugeot diesels are selling so well, remembering that the company commenced experimenting in that category 70 years ago.