A SPRINT SPECIAL
F. M. Wilcock, who ran the Percy Lambert Talbot replica at last year’s Brighton Speed Trials, is building a truly exciting car for the next event of this sort. Into a chassis of his own construction he has mounted a war-time Rolls-Royce “Merlin” aeroplane engine. The chassis has specially deep side-members, braced by old Rolls-Royce cross-members, and the wheelbase measures some 14 feet. Each wheel is sprung independently, by vertical coil springs, and each is driven by a separate shaft running from a transfer gearbox.
The Merlin engine is back-to-front in the chassis, its former propeller reduction gearbox removed and part of its crankcase cut away to enable a flywheel and clutch to be fitted.
The drive goes to a vast, separate A.E.C. preselector commercial vehicle gearbox and thence to the transfer box. Bottom gear is 5 to 1 and top is distinctly higher than direct drive. To accommodate the independent front suspension an Alvis-like steering layout is employed, and the steering column and Bishop steering box came from one of H.M. King Edward VII’s Daimlers.
The engine gives something like 1,500 b.h.p. at full boost. The centrifugal supercharger is retained but all this power is not expected to be exploited over the Brighton kilometre, as the boost is variable. Dunlops are supplying racing 7.00 by 18 tyres for the disc wheels – the same size as used on the back wheels of the B.R.M. Cooling is by an adapted Spitfire radiator on the nose of the car.
This great car should enliven the Brighton Speed Trials on September 5th. Last year Ted Lloyd-Jones made fastest time of the day in 23.91 sec. He, too, used four-wheel-drive and a Rolls-Royce aero engine, but although his rear-engined Triangle Flying Saucer is as compact as Wilcock’s new car is long, his 21-litre unsupercharged Kestrel develops less than half the horsepower of the 37-litre Merlin that reposes in the nose of the Wilcock car.
AN H.R.G DEVELOPMENT
Two changes of power unit which will take effect later in the season have been announced by the H.R.G. Engineering Co., Ltd., of Tolworth, Surrey. Since 1939, this company has been installing suitably modified Singer engines in its 1,100-c.c. and 1 1/2-litre sports 2-seaters, these power units being of the single-overhead-camshaft type and having four-speed synchromesh gearboxes mounted in a unit with them. Up to now, the 1 1/2-litre engine has been a high-compression, twin-carburetter version of the 12-h.p. Singer which was designed before the war, but for production reasons this will, in the near future, be superseded by an adaptation of the post-war S.M. 1500 design. Similar in general layout to its predecessor, this 1,497-c.c. engine has a 5 mm. larger cylinder bore and 13.6 mm. shorter piston stroke, twin semi-downdraught S.U. carburetters, and a compression ratio of 7.4 to 1, giving an almost identical power output of 65 b.h.p. at 4,500 r.p.m. The price of the H.R.G. 1,500 will be unchanged when this engine is installed.
Development work is also in progress at Tolworth on a twin overhead-camshaft engine, which will eventually become available to customers seeking maximum performance. Initial testing of the new cylinder head is being done on a 12-h.p. Singer engine of the obsolescent model, which already shows a 30 per cent. increase in torque at 4,500 r.p.m., and is expected to attain even greater relative improvements in peak power; by the autumn, it is anticipated that conversion of existing cars to twin-overhead-camshaft engines will be possible if owners so desire. Eventually, however, production will be concentrated on a substantially similar twin-camshaft cylinder head for the Singer S.M. 1500 engine, as an alternative to the less costly single-overhead-camshaft S.M. 1500 engine.
The twin overhead camshafts for the new head are driven by duplex chains, as is the single overhead camshaft of a normal Singer engine, a short primary chain from the crankshaft nose reducing the r.p.m. and a longer secondary chain guided by three jockey pulleys driving the camshafts. The combustion chambers are of approximately hemispherical form, each having two valves inclined at a wide angle and an almost-central 10-mm. sparking plug.
Cast in aluminium alloy, the cylinder head provides unobstructed inlet and exhaust ports, as well as ample space for coolant circulation. Inserted valve seats are used, and internal ribs provide both stiffening and improved heat transfer above the exhaust-valve seatings, each of which has a vertical cooling-water offtake. The valves are operated by direct thrust from the cams, side thrust being taken by tappets of the inverted-piston type, which also enclose screwed clearance-adjusters.
Although production examples are unlikely to be available in time for this season’s sports-car races, this new Singer-H.R.G. unit gives promise of being amongst the most potent 1 1/2 litre sports-car engines in production.
Shell-Mex and B.P. Ltd. issue a very thick, heavy booklet,”1952 Shell Successes,” containing some very fine “shots” of motor-car and motor-cycle sporting occasions, printed on excellent paper. They also publish a useful little phrase book, “Bon Voyage.” in 15 languages, which contains motoring phrases, conversion tables,. etc., to assist the motorist abroad. Both are available free of charge on application to Shell-Mex House, Strand, W.C.2.