EXPLODING A FALLACY AERO MOTORS VERSUS MOTOR-CYCLE ENGINES FOR USE IN CAR CHASSIS
THE V-twin cycle-car is by no means dead for sprint work, while quite a number of readers are interested in this type of vehicle for road work. In the latter case interest centres round the Morgan three-wheeler converted to a four-wheeler. In this connection we have had a most interesting correspondence with Mr. Sidney Allard [Correct spelling: Sydney Allard], who, before lie commenced to drive Ford V8 cars in trials, used to race Morgans at Brooklands, and, in 1932, built a fourwheeler Morgan for trials work. This car was a special job throughout, with a Moss four-speed and reverse gearbox and open shaft drive to the rear axle, which was sprung on eight transverse quarterelliptic springs. The engine was a tuned 8/50 water-cooled J .A.P. Mr. Allard tells us that his later experience with the Allard-Special cars has convinced him of the extreme importance of good powerto-weight ratio and if he was again building a four-wheeler Morgan he would use a 1929-type two-speed chassis and mount a simple axle on splayed-out quarterelliptic springs. His shaft-drive car required a li-litre axle assembly to withstand the hairy-legged horses of Mr. J. A. Prestwich, and this, in conjunction with the car-type gearbox and special suspension assembly. rendered the car rather heavy. Even so, it did a genuine 50 m.p.g., was capable of some 80 m.p.h. and could beat a V8 Ford on acceleration. All of which points to the fact that a converted Morgan should be a very amusing road
motor. Other V-twin four-wheelers of recent date include Sulman’s MorganG.N., Lones’s Morgan “Tiger Cat,” and the little 750 c.c. Andre V6, that went into short-lived production about seven years ago. Also the B.S.A. V-twin, not to be confused with the flat-twin B.S.A., circa 1923. When the subject of cycle-cars crops up, either for racing or road use, the question of a suitable engine arises, and we have frequently heard the view expressed that old light aeroplane engines would be admirable units for the job. With this view we cannot agree, so far as sheer performance is concerned. In 1924 three special light aero engines appeared, following the frequent failures of unsuitable standard motor-cycle engines in the Lympne Light Aeroplane contests of 1023. These engines were the A.B.C. ” Scorpion,” the British Anzani, and the Bristol ” Cherub.” Now consider the characteristics of these engines. The A.B.C. ” Scorpion ” was a flat-twin which gave 30 b.h.p. at 3,000 r.p.m. and weighed about 93 lb. The British Anzani was a V-twin with four valves per cylinder, for which the makers preferred not to issue power curves—at any rate to the aeronautical Press. The Bristol ” Cherub ” gave 32.6 b.h.p. at 3,200 r.p.m. and weighed 81 lb. There was also a Blackburne Radial of 1,100 c.c. (three cylinders), giving 38 b.h.p. at 3,800
r.p.m. It will be recalled that one of the Bristol ” Cherub” engines was installed in an A.B.C. which F. C. Gordon England—the man who afterwards showed the world that the Austin Seven is rather more than just a comic utility car—drove in one of the early 200 Mile Races. Last summer we met a garage owner near Brooklands who was at A.B.C.’s at the time and he told us that this experiment was hardly a success. Jumping a little matter of fourteen years, let us consider the light aero engines available to-day. The .Anzani is still with us, made by Luton Aircraft for their ” Buzzard,” and it gives 85 b.h.p. at 3,150 r.p.m. and weighs 105
lb. dry. The two-stroke Scott gives 28 b.h.p. at 2,000 r.p.m. from 652 c.c. and weighs 85 lb. The Coventry Victor 11-litre air-cooled flat-four does 40 b.h.p. at 3,000 r.p.m. and weighs 140 lb.
The A.B.C. is no longer marketed. Now let us compare these outputs with modern racing motor-cycle engines. The 1,000 c.c. racing J.A.P. V-twin, on racing fuel, gives just over 54 b.h.p. at 5,000 r.p.m. and 35 b.h.p. at 3,000 r.p.m., while the maximum torque is 62 lb./ft. at 3,200 r.p.m. The 8/80 o.h.v. J.A.P. twin, on racing fuel, manages 761 b.h.p. at 6,300 r.p.m., and 67 b.h.p. at 5,050 r.p.m.
The 500 c.c. Dirt Track J.A.P. engine, which would be most interesting in a three-wheeler or in a four-wheeler commanding the 44/l0/0 annual tax, gives 38 b.h.p. at 5,800 r.p.m., and 30 b.h.p. at 4,000 r.p.m., with a maximum torque of 40 lb./ft. at 3,500 r.p.m. The 1,000 c.c. J.A.P. weighs 126 lb., and the magneto and carburetter bring
the weight up to 136 lb., and the 8/80 J.A.P. comes out at 109 lb., or 127 lb. with twin gas-works and twin powerstations. So it is evident that the racing motor-cycle V-twin gives considerably more power than the aero-engine, and power is what matters to sprint exponents. However, it must be conceded that the J.A.P. motors quoted are full racing units, functioning at high revs, on racing fuels. Whereas the aero-motors turn over lazily, and should be happy on No. petrol, for the 1924 units mostly had a compression-ratio of around 5 to I, and the 1938 Coventry-Victor and Luton Anzani motors have ratios of 6.2 and 5.5 to 1 respectively. We had hoped to quote further motor-cycle figures by way of comparison, but a polite note from Burney and Blackburne informs us that their whole works now makes armaments, not motors. The only other proprietary V-twin on the market is Associated Motorcycles’ 990 c.c. Matchless, which is a 500 square side valve motor giving 26 b.h.p.
So the issue remains an open one, though J.A.P.s can hand it out for sheer b.h.p. But an aero-engine might be quite good for road work, and would add character to a class of vehicle which, as a type, is. distinctly uncommon. The Morgan. three-wheeler seems the most adaptable chassis for purposes of conversion, and we would gladly publish correspondence relating to the behaviour of such cars and bow the job should be carried out. Ordinary chassis are out of the question, because seldom will the transmission and back axle stand the kick of that fierce horse-power which has its habitat in two big pots, nor is it easy to couple
up engine and clutch. And the early cycle cars, like G.N., or A.B.C., possess shortcomings, such as small tyre sections and inadequate brakes, which few can tolerate when fairly serious sporting motoring is contemplated. So a Morgan conversion appears to be the solution, the difficulty being to mate a full-width chain-driven rear axle to the very narrow quarter-elliptic spring and frame assembly. Are we too optimistic in believing a V-twin four-wheeler to be an essentially sporting and economical proposition ? And, if not, how is it done ?
SUGATTI CLUB FIXTURES FOR 1939
The Bugatti Owners’ Club has issued its 1939 Fixture List. This year the Opening Rally goes back to Huntingdon, but Prescott will see four meetings, or five including the Vintage S.C.C. Meeting. These comprise the Open International fixture of July 30th, two open meetings and two club meetings—will resurfacing be necessary each winter, as at Brooklands ? The Club has recently elected twenty-three new members. The January ” Bugantics ” is rambling in make-up and not up to its usual high standard. The fixture list is !—
March 8th. A.G.M.
April 9th. Opening Rally.
May 14th. Prescott Spring Open Meeting.
June 1 Ith. Prescott Club Meeting. July 80th. Prescott International
Sept. 24th. Prescott Open Autumn Meeting.
October 29th. Welsh Trial. November 18th. Night Trial.
Amongst Edwardian motors available to enthusiastic members of the Vintage S.C.C. are a 1905 two-cylinder rearengined Riley ; two Bebe Peugeots ; a 14 h.p. Decauville ; a 1914 12/14 h.p. Mors ; a 1908 Humber ; a 1911 two-cylinder Stellite ; a 1904 8 h,p. Renault ; a 1911 two-cylinder 8 h.p. Renault ; several Renault landaulettes and a 1910 Austin
“Twenty.” Prices range from 44 to about 00.
Last month we mentioned a Bata cover which seemed to have considerable possibilities under the new standardtyre trials ruling, that the R.A.C. has banned it. Bata tyres have been represented in this country for only six months and already they show a profit. If the demand is sufficient a British factory will
be established. The agents are Atlas Importers Ltd., and the sales manager Is Capt. Crossley.