"Motor Sport" visits Bourne to inspect the first of the B.R.M. Grand Prix Cars
On December 10th we were able to attend a private try-out of the prototype B.R.M. racing car on Automobile Developments’ private aerodrome. It is the first of a team of Grand Prix cars built by the British Motor Racing Research Trust with the object of promoting British prestige amongst strong foreign competition in International motor-races. Unfortunately the weather conditions were against any serious fast motoring and it was so cold that the car had no hope of reaching a reasonable working temperature. Our first impression of the car, which Raymond Mays was driving round the circuit, was that it was a most squat and purposeful-looking machine. Ground clearance appeared to have been reduced to the minimum and the overall height was very small; just how small, we were able to judge when the car was stopped and we joined Mays on the runway. Outwardly the car had an air of stark simplicity, there being no opening in the bonnet or sides, while the radiator intake was very aircraft-like in appearance, the aircraft-type pressurised radiator block itself being very low and wide. This width was maintained in the body down to the rear of the cockpit and the tail was reminiscent of a Type 158 Alfa-Romeo. A further attempt was made to get the oil temperature up, the engine “warming up” at 5,000 r.p.m., and being blipped to 7,500 r.p.m. with no effort at all, but it was obviously the wrong day for any serious motoring, so a return was made to the garage. Here we were able to have thorough look round the car and the bonnet was removed, displaying a power unit which, at first glance, made such things as Alfa-Romeos and Ferraris fade into insignificance. The bore and stroke is 49.53 by 48.26 mm. (1,487.7 c.c.) and the 16 cylinders are arranged in a 135-degree Vee-formation, each alloy block of eight in one piece with the crankcase and incorporating wet cylinder liners. These liners are spigotted into the crankcase and protrude above the block. The top of the liner forms a further spigot on which the head pulls down, as on a Norton Velocette racing engine, the joint being made by an aluminium ring. This necessitates a high degree of precision machining to ensure that all four combustion spaces seat evenly. High Duty Alloys supplied the castings. The capacity of each cylinder is thus under 93 c.c., and the total piston area is 47.78 sq. in. Two overhead camshafts are provided above each cylinder block, running in roller bearings and operating the valves via light-alloy fingers. The exhaust valves are sodium-cooled and coolant reaches their guides. They are driven from the centre of the crankshaft by a train of straight-cut spur gears; the camshaft covers are completely devoid of bulges. The valves are inclined at 87½ degrees in deep, Riley-like hemispherical combustion chambers and the inlet valve is appreciably larger than the exhaust valve. The inlet ports are siamesed and single rectangular exhaust ports are used. A water gallery cools the exhaust valves, a separate water off-take being placed adjacent to each valve. Hairpin valve springs are used and all oil-ways are cast in the heads. The cylinder heads are of light alloy with steel valve inserts and single masked sparking plugs are mounted centrally at an angle in each cylinder and fired by a coil ignition system. The Exide battery is housed in the tail of the car and the Lucas coils, mounted behind the radiator, feed to four Lucas distributors driven from the front ends of the crankshafts, each distributor looking after four cylinders. The crankshaft is built-up in two halves to accommodate the central drive for camshafts and auxiliaries and runs in ten main bearings, with two connecting rods side by side on each crankpin. Vandervell plain bearings being used. The big-ends are of the two-bolt type. Lubrication is by a dry-sump system having two pressure and four scavenge pumps and there is a large centrifugal water pump each side of the base-chamber.
The supercharging arrangements are most unusual for a racing-car engine, there being a Rolls-Royce two-stage centrifugal supercharger. This is compact, being about 10 in. in diameter, and is mounted in front of the engine, slightly offset. Two S.U. carburetters, mounted across the chassis, feed into the blower and the end of the volute feeds over the top of the engine, splitting into two cast-alloy pipes, the lower one branching again to feed the front eight cylinders and the upper one doing likewise to feed the rear eight cylinders with a blow-off valve for each pipe. The pipes feed fabricated steel manifolds. However, a petrol injection system is being tested on the second engine, with an S.U. fuel pump injecting fuel into the eye of the primary supercharger. There is an aircraft-type boost regulator to control maximum boost. The supercharger is geared up to run at some 40,000 r.p.m. at maximum engine speed and is driven by epicyclic gears from an output shaft running beneath the crankshaft and would appear to have some sort of free-wheel device fitted to its drive. When the engine was switched off we could distinctly hear the supercharger windmilling on, to come to rest some time after the engine had stopped. Presumably this will relieve the rotors of a great deal of reversal strain, which the supercharger of a road-racing engine is bound to experience. Each group of four cylinders has a “Bugatti”-shaped exhaust manifold feeding into its own tail pipe. The exhaust note from this small-cylindered 1½-litre is difficult to describe, but the noise the car emits is decidedly impressive and has that very crisp note peculiar to highly-tuned engines. This wonderful power unit is intended to run up to 12,000 r.p.m. and is said to give over 400 b.h.p. From the ends of the camshafts, drives are obtained for aircraft-type fuel pump and electric rev.-counter drive. The engine has been tested on a Heenan and Froude brake and is started up by a Ford V8 engine. So easily does it start that a touch on the Ford starter button sets the B.R.M. engine going. Stub exhausts are used on the test bed to enable mixture strengths to be checked. The rev.-counter in the test-house was made locally and is accurate to 0.1 per cent.
This almost square engine, being of very small overall height, is mounted fairly high in the chassis, off-set to the left and also lower at the rear than at the front. The housing for the multi-plate Ferodo-lined clutch protrudes into the cockpit with the afore-mentioned output shaft running diagonally across the floor of the car. The output shaft runs at approximately half crankshaft speed. A five-forward and one-reverse-speed gearbox is mounted on the chassis at the rear, in unit with the differential housing, the differential being of the ZF limited-slip pattern. An open gate gear-lever mounted on the right of the driving seat reminds one of that found in an Auto-Union. The driver’s seat is very comfortable and gives remarkably good support not only to the body but also to the legs. Although the driver sits very low, alongside the drive shaft, vision is superb, both front hub centres being visible. At present the steering column is rather too horizontal, but is due to be modified to give a greater degree of inclination. The column runs over the top of the engine to a worm and nut mechanism by the track-rod pivots which are mounted behind the radiator, universal joints looking after changes of direction between the steering wheel and the steering box. At the moment the cockpit abounds in instruments, as the first car is in the nature of a test-bed; among the instruments is an electric rev.-counter, reading to 11,000 r.p.m. There are finger grips on the leading edge of the three-spoke Ferrari-like steering wheel.
The chassis layout follows conventional Grand Prix practice, with i.f.s. and de Dion rear suspension, but many unusual and ingenious features are incorporated. The chassis frame consists of two parallel side-members, each being constructed from two small-diametered steel tubes, one about 6 in. above the other and the two joined by steel sheet, welded to the tubes on each side. The front tubular steel cross-member carries the pivots for the lower trailing links, the upper ones being mounted on extensions from the frame. These links are so highly polished that they appear to be plated. The general layout, of trailing links and ball-pivots in place of king-pins, follows the Porsche layout used on the E-type E.R.A.s, but the top link is extended forward beyond the pivot and operates a four-lb. Lockheed oleo-pneumatic strut about the size of a Newton shock-absorber. Similar struts are used for the rear suspension, the layout being typical Grand Prix de Dion, as used on the 3-litre G.P. Mercédès-Benz, with pot-type inboard and hook-type outboard universal joints and with the short link normally joined to the torsion bar joined to the strut; the five-speed gearbox has its shafts running transversely across the chassis, constant-mesh gears and its own oil pump. A cross-member under the driver’s seat carries a bearing for the output shaft between engine and gearbox and gearbox and final drive are mounted on the rear tubular cross-member. Once again a new development peculiar to the B.R.M. is seen in the 14-in. Girling hydraulic brakes, all of which contain three leading shoes; there are two independent pipe circuits. Two fuel tanks are fitted, one in the tail and the other in the shape of a saddle over the driver’s legs, joined by large-bore pipes running along each side of the cockpit, in a similar fashion to that employed on the 3-litre 1938/39 Mercédès-Benz racing cars. An oil tank is fitted alongside the engine on the right and the radiator header tank is situated behind and above the engine. The B.R.M. is stated to have a starting-line weight of approximately 17 cwt., and a dry weight of rather over 14 cwt., and its maximum speed is estimated at Bourne as 200 m.p.h. The wheelbase is 8 ft. 2 in., the front track 4 ft. 4 in., the rear track 4 ft. 3 in., and height to scuttle only 2 ft. 6¾ in. At present 5.25 by 16 front and 7.00 by 17 rear Dunlop racing tyres are fitted.
The engine will be run on Vignol oil and methanol fuel.
At the time of inspection, the engine had completed many hours on the test-bed and the car had covered some 60 laps of the Folkingham aerodrome circuit, all with very little bother, although, of course it has not been really extended. Incidentally, how fortunate that B.R.M. have their own airfield! As yet nothing definite is known about possible drivers for the immediate future, although Peter Romaine, who has done so well in his first year of motor-cycle racing, is said to be a protegé of Raymond Mays’, and he may become a future member of the team, while it is rumoured that a world-famous racing motor-cyclist has also been approached. For our part we can only make wild guesses the same as everyone else, but if the team has to be British, then we would suggest P. D. C. Walker, A. P. R. Rolt and F. R. Gerard, excluding L. G. Johnson and G. Abbecassis only because they have their own racing programmes in hand.
We have waited patiently for some real news about the B.R.M, and have often wondered why progress appeared to be slow, but having now seen the car it is easy to realise that it’s an advance over anything known at the present time. We can understand what a vast undertaking the British Motor Racing Research Trust has made itself responsible for and can appreciate the amount of work that must have gone into the project, which had to start from scratch. From a technical viewpoint, the B.R.M. is remarkable and should satisfy anyone who doubted this country’s prowess in racing-car design and construction.
Harry Mundy is in charge of detail development, Eric Richter looks after engine design and Frank May is the chief draughtsman.
If the first three cars can be completed in time for the Grand Prix d’Europe the good wishes of every enthusiast will go with the cars when they leave the starling line.