The diesel background

The Editor looks at some of the Early Developments of a Type of Engine which may soon find a New Lease of Life in the Private-Car Field.

THE panic is on over the oil-situation, and no mistake! Even when the RAC Rally had but a few hours to run, my friend Robin Richards, who was reporting it for the BBC and whose news-flashes from the circuit have often kept me in touch with events I have not attended, was asked by the Studio what he felt about so many competition cars using so much fuel and Robin promised to have an immediate word with the RAC, as if that would do any good with Makinen and the victorious Ford Escorts were nearly home and dry! However, all this pessimism has made me think in terms of other fuels. Paraffin is illegal for cars, so you turn to Derv, and the compression-ignition engines which can digest it. They could well come into their own in private cars; if the fuel shortage gets worse; they are already well-established in the taxi and commercial-vehicle fields.

There is nothing very new about the diesel. Rudolf Diesel took out the first patent in 1892, stating its advantages over the petrol-vapour engine as a lower fire-risk, lower fuel-thirst and a long service-life. The last two attributes are why the c.i. power unit has appealed to commercial-vehicle users; the first had some merit for aeroplanes, and was flirted with in aeronautical circles, before the war. When Diesel’s master-patent expired in 1907 some motor companies stepped up their c.i.-engine researches, just as for a long time the Wankel engine, gas-turbines and rotary valves have been investigated by those who have not so far adopted them commercially. The early difficulties of making reliable injection pumps and nozzles, and of controlling them, made progress slow and it was not helped by the Inventor, who was lost from a cross-Channel ship when on his way to England in 1912, By 1923, however, with a forcing-house war behind them, automotive engineers were making better progress. Benz of Mannheim had a satisfactory four-cylinder c.i.-engine out that year. Although it developed only 45 b.h.p. at 1,000 r.p.m., it was demonstrated in a huge 5-ton truck. From this stemmed the notable exhibits at the 1924 Berlin Show, where three diesel engines were shown, a Benz pre-chamber, a MAN direct-injection and a Daimler-Benz air-injection. After Benz had merged with Mercedes in 1926 Daimler-Benz chose to make the prechamber-type of diesel engine, developed at Mannheim. They soon brought out the first six-cylinder vehicle diesel engine, which gave 70 b.h.p. at 1,300 r.p.m. To the three advantages already attributed to the heavy-oil engine, over the petrol engine, can be added its ability to develop peak power at comparatively low r.p.m. and the low pollution factor of its fuel, the latter of growing importance in the World of today. The aforesaid long life stems from the fact that the very high cc. required for sparkless combustion necessitates a rugged bottom-end, while the injection pump is more or less a precision-built component, even if considerable progress was made when Bosch contrived to series-produce such pumps in 1927.

Do not imagine that the diesel is a lost cause. Mercedes-Benz brought out the first diesel-powered passenger car in 1936 and at that subsequent, memorable Berlin Show when Hitler had GP Mercedes and AutoUnions running up to it through the public roads, this and a Hanomag diesel were shown. Mercedes have since made over a million c.i.-engined cars, and today these represent 35% of their passenger-car output. The first diesel lorry engines with direct-injection arrived by 1964 and today Mercedes-Benz have as their most impressive vehicle diesel the type OM 403 V10-cylinder, which has 320 h.p. with which to propel their largest commercial vehicles. They have also recently introduced a new diesel saloon, the 240D, the 91 x 92 mm. four-cylinder 2,404 c.c. engine of which gives an output of 65 b.h.p. at 4,200 r.p.m. This is quite a high speed for a c.i. engine and although maximum power is not much more than a third of that developed by the 2.7-litre 280E, this petrol burner peaks at 1,800 higher r.p.m. and gives its maximum torque at 2,100 greater r.p.m. than the diesel-powered 240D.

Only Mercedes-Benz with this 240D, and their well-known 220D, still push diesel cars in Britain, perhaps because there is less advantage under the economy heading, diesel fuel now costing approximately the same as four-star petrol. However, there is still the lower consumption of the oiler to consider, especially at the present time, and its lower pollution factor. So I think diesel-engines may well go under the bonnets of more private cars, quite soon. They are available abroad from most of the established manufacturers, if only for taxi-work.

My attention was first drawn to the dieselpowered private car when I saw running down Great Portland Street, where I used to motor-browse as a youth, a chassis devoid of bonnet and body, with its single-cylinder engine exposed naked and unashamed for all to see. The lesser cyclecars sometimes had single cylinders but this was a substantial vehicle, so the “one-lunger” engine was puzzling. It also had a square water-jacket and although I knew enough not to fall into the trap of supposing it to have a square piston in a square cylinder “bore”, it was not a vehicle easily forgotten! In fact, it was an experiment, using a diesel engine, indistinguishable at first glance from a Lister stationary engine, which C. B. Wardman of Great Portland Street had put into a Vulcan chassis to show that a magneto and a carburetter were unnecessary adjuncts to motoring.

In those days the disadvantages of the c.i.-engine for car propulsion were the smell of the fuel and “diesel knock”, particularly when idling. I cannot think that these shortcomings were well camouflaged in this Vulcan-ised experiment, because a “single” of a mere 594 c.c. should have thumped horribly and the smelly fuel was carried in an exposed barrel strapped across the rear of the chassis and labelled “Pratts Diesel Fuel-Oil”. The engine was a CLM opposed-piston two-stroke diesel, made under the Junkers licence by the Compagnie Lilloise de Moteurs in France. As the thing developed a mere 10 h.p. at 1,200 r.p.m. and was happier giving eight at 1,000 r.p.m., top speed was only 20 to 25 m.p.h. But it was apparently unexpectedly docile, and a prompt starter. Moreover, it did over 50 m.p.g. on fuel which in those days, 1930, cost only 5d. per gallon, so its economy was notable. Another point about the c.i.-engine is that it is impervious to damp, because it has no electrical ignition system, which may be why this CLM-Vulcan was able to dispense with a bonnet.

The cost of construction was against the diesel engine, due to the intricacy of the injection pump and the need for heavy construction throughout the engine. I recall that the repair of such pumps was quite a business. One ancient man who repaired our magnetos in Wimbledon in those days had the necessary skill—he also had a derelict Bebe Peugeot which was bought by a friend when I refused to pay the few pounds requested, valuing at an equal number of shillings; but that is another story. To obviate the need for a distribution system, the Hesselman six-cylinder heavy-oil engine had a separate pump for each cylinder, but it was a cheat anyway, using electric ignition to enable a normal c.r. to be used. But by 1930 Packard had a nine-cylinder radial diesel arm-engine designed by Capt. Woodston which poked out 225 b.h.p. at 1,900 r.p.m. for a weight of 2.27 lb. per b.h.p., from 16-litres, on a c.r. of 16 to 1. I have heard that the pots on the early Packard engines were held to the crankcase by steel straps tightened by turn-buckles and that if either broke, all the cylinders flew off. So perhaps the Bristol Phoenix diesel aero-engine was to be preferred! Junkers made good progress with opposed-piston diesel aeroengines and on land the racing motorists were soon proving that the c.i.-engine was no sluggard.

In the 1933 Monte Carlo Rally a 1925 3-litre Bentley fabric saloon driven by Lord de Clifford and using a Gardner 4LW 5½-litre four-cylinder diesel engine developing some 68 b.h.p. at 1,700 r.p.m. (this having been an experiment by the engine manufacturers, well-known in the marine and commercial-vehicle field) made best performance by a British entry. A normal 2-litre Lagonda was converted to run on heavy oil, at about this time, by two enthusiasts who were at the Military College of Science at Woolwich. They claimed to have done a 650-mile tour in it at a cost for fuel and lubricating oil of just over 11/- (55p). At Brooklands, G. E. T. Eyston demonstrated his idea of a diesel-car, with an AEC ‘bus engine of 9-litres capacity in an old Chrysler chassis. Vanden Plas made a closed racing body for it and although there was then no diesel-class, Eyston took the car, which he called the Safety Special, out in October 1933 and showed the Press that it could do a timed 106.68 m.p.h. over the kilometre. It had a racing exhaust system, used BP fuel-oil, Castrol lubricating oil and Dunlop tyres, and as it was pouring with rain, Eyston had the laugh of us, in his enclosed saloon! Soon after this the FIA introduced a c.i. records category, although not divided up into capacity classes. Eyston used his front-wheel-drive record car “Speed of the Wind” with a Ricardo diesel-engine to break records at Pendine Sands. Later Eyston took the saloon AEC to Montlhery and captured class records up to three hours at nearly 98 m.p.h., having got the 100-mile class record at 102.956 m.p.h. After which a front wheel came off the now-aged Chrysler chassis, while Bert Denly was driving. In improved form the car too a diesel records from 50 km. to 24-hours, the last-named record at 94.99 m.p.h. These figures were bettered by others, but in 1937 the AEC-Chrysler recaptured some of its lost honours, with the hour at 105.59 m.p.h., the 12-hours at 97.05 m.p.h. and the 24-hour run done at 97.06 m.p.h.

R. J. Munday found a use for his old Thomas Special “flat-iron” in 1935, by installing a 2.7-litre 85 x 120.6 mm. fourcylinder Perkins diesel engine of a type called the “Wolf”, which was already being tried out in small vans and in a Hillman private car. This necessitated a raised bonnet, which destroyed the ultra-low appearance of the Thomas Special. But the results were good. Munday ran for 100 miles at speeds of over 88 m.p.h., the engine having been tuned to give 20 more b.h.p. than its normal 45. With a Zoller supercharger fitted—it is easy to supercharge a diesel engine as there is no problem about whether to blow air or suck mixture, only pure air being involved—the Perkins-Thomas did the two-way kilo. at 94.7 m.p.h., and over 97 m.p.h. in one direction, on some 87 b.h.p. This was sufficient for the Perkins Company to issue an advertising brochure about the runs and when c.i.-records were officially recognised these Brooklands’ figures were accepted.

I recall a 15/18 Lanchester fitted about this time with a Tippen diesel engine and that the speed work at Brooklands had been foreshadowed when the American driver C. Cummins had brought a Cummins diesel-car to the Track in 1932 and demonstrated it (lap speed, 74.63 m.p.h.), apparently gaining life-membership of the pre-war BARC as a reward. It was a 5.9-litre Cummins U-type engine in a Duesenberg chassis. At Indianapolis, too, there was notable Cummins-Diesel activity, up to 1952. In 1935, encouraged by the success of their Gardner Bentley in the 1933 Monte Carlo Rally, Gardner’s installed their latest idea of what a car-diesel engine should be, in a 1932 Lagonda tourer which outwardly looked as handsome as these Lagonda sports cars always do. The 4LK engine was a light-alloy 3.8-litre four-cylinder unit weighing 684 lb. with starter, and developing 83 b.h.p. at 3,000 r.p.m. on a c.r. of 14 to 1. As nice a piece of machinery as the power unit it replaced! This diesel Lagonda gave fuel consumption figures of 42 to 48 m.p.g. at road averages of over 30 m.p.h. and was quite capable of climbing Bwlch y Grocs at a 30 m.p.h. average. It went from to 60 m.p.h. in 24.4 sec. and its top speed on a 3 to 1 axle ratio was 83 m.p.h.—quite an acceptable performance from a petrol-engined sportscar forty years ago.

From about that time onwards, dieselengined cars were quickly developed all over Europe, with Citroën well to the fore with a 1.8-litre Ricardo designed unit, which no doubt powered the Yacco Special which was soon to show that c.i.-records could be taken with quite a small oil-engine.

By 1939, just before the machinations of Hitler stopped progress, the record-book showed that Eyston had the fastest c.i.-record, at 159.1 m.p.h. with his “Flying Spray”, that a 2-litre Hanomag had done almost 97 m.p.h. for five kilos., and that Yacco held all the long-distance ones, so wellsuited to a diesel engine, including eight days at 68.18 m.p.h. In the production category, Studebaker in this country were willing to install the 4.7-litre six-cylinder Perkins Panther diesel engine which gave 85 b.h.p. at a modest 2,000 r.p.m. and which was superior to the current Ford V8 30 in respect of weight-per-litre but not weight-perhorse-power. Whereas Gardner and others had been using injector pumps made under Bosch licence, Perkins had CAV sprayers, a CAV pump and a CAV pneumatic governor on their Panther engine.

Maybe all these things had been anticipated on the Continent, for as early as 1923 Peugeot had submitted to the Press for test two cars identical except for their engines. One had a 2,199 c.c. two-cylinder two-stroke Tartrais-type oil engine of 100 x 140 mm., the other a 2,590 c.c. four-cylinder 85 x 130 mm. petrol engine. On an identical journey of just over 103 miles, at an identical average speed of fractionally above 32 m.p.g., the oiler returned 19.88 m.p.g., the petrolengined car 18.87 m.p.g. But the costs for fuel were equivalent to 28/2d. and 7/3d., petrol against diesel. Both cars had the same gear ratios and tyre sizes and the oiler was timed to do a two-way speed of 37.16 m.p.h., the petrol Peugeot 45.48 m.p.h., over a kilometre which did not permit top pace. MOTOR SPORT kept its readers au fait with such developments. In 1950 David Scott-Moncrieff reported for us on the Mercedes-Benz 170D oil-engined model, in an article called “D For Diesel Day”. He wrote of over 44 m.p.g., cruising for kilo. after kilo. at just over 62 m.p.g., and remarked that as “in every country I can think of, diesel fuel is cheaper than petrol, so for anyone covering a large annual mileage a very large hole is knocked in running costs”. The 170D had a 1.8-litre engine giving 38 h.h.p. at 3,200 r.p.m. on a 14 to 1 c.r.

There were by now sufficient diesel engines about for them to replace worn-out petrol power units in big vintage cars like 6½-litre Bentleys, 35-120 Daimlers, 36/220 Mercedes-Benz and 4½-litre Lagondas, whose original characteristics they even emphasised. I had experience of such a conversion when I borrowed a Daimler Double-Six Charlesworth limousine in 1952, in which a Perkins P6V diesel engine had been inserted. It was the occasion of a wedding, so this seemed an excellent idea. But all that happened was that we were mistaken for one of the wedding taxis! This was a Beardall conversion and although it smelt of its fuel, the idea appealed of doing 150,000 economical miles without the need of an engine overhaul, on fuel which at the time cost 3/1d. a gallon when petrol was 3/6d. a gallon.

I remember a funny incident with such cars around this time. Two immaculate 540K Mercedes-Benz arrived early at a local rally my wife had organised, their occupants settling down to a picnic lunch, confident of taking home the top prizes in the Concours d’Elegance. Alas for them, the rules included marking for original specification and when the beautiful white bonnet’s were opened, both cars were seen to possess diesel engines. The owner and his lady drove away long before the end in undisguised disgust . . .

In 1934 I sampled a diesel-engined Morris Oxford Series VI at the invitation of BMC, just as I had earlier sampled a car proffered by Perkins. This was a 1½-litre giving 40 b.h.p. at the high diesel speed of 4,000 r.p.m., on the higher c.r. of 23 to 1. I found it smooth and smokeless and able to cruise at 60 to 70 m.p.h. on a 4.5 to 1 top gear. Fuel economy wasn’t checked but starting from cold was accomplished in about 20 seconds, using the “ignition-key”-controlled heater plugs. But I note that I said bets could be won when it was idling, because the “diesel knock” sounded like “run” bearings and that the cost was over £102 more than that of the equivalent petrol-engined Morris.

I think I must also have driven dieselengined Mercedes-Benz, Standard Vanguard and other cars but can recollect nothing about them. As the price of heavy oil rose to meet that of petrol and when the latter was freely purchasable, interest in diesel cars on the part of private owners waned. But with the need to conserve fuel, remembering the 30 to 40 m.p.g. obtainable from the early 5-litre to 7-litre oil-engines, and with the present pressing pollution problems (diesel fumes look horrid and smell worse but are apparently less harmful than the exhaust of cars burning leaded-petrol), I think the c.i.-engine may soon be staging a private-car come-back. It would be interesting to know whether readers with experience of the type consider that it lives up to its reputation for longevity and low running costs.—W.B.