Under the Cam Covers
To those in the know, racing engines sometimes appear to resemble those Russian dolls; remove one layer, and another is revealed; remove that, and there is yet another underneath. The camshaft cover of an Indy engine may read Chevrolet, but the engine is actually the product of Ilmor, a British firm. In Grand Prix racing, the Ford engine is the Benetton was designed and manufactured by Cosworth. Below the engine manufacturers are another layer of firms, component manufacturers, like Mahle (pistons), Goetz (rings), Prankl (con rods), Vandervell (bearings) and Schmitthelm (springs). And even in the area of design, there are a small number of R & D firms or consultants who provide expertise on such matters as cam profiles or combustion, etc. Longtime readers of MOTOR SPORT will know that many of the racing engines in Britain and America in the 1950s and 1960s, such as the Le Mans winning Jaguars or the ‘Hemi’ Chrysler V8s, benefited from breathing improvements made by gasflow expert Harry Weslake. Alas, Weslake is no longer with us, but other firms now fulfil a similar role, and chief among these is Scott Russell Engine Design and Development.
Unlike most of Britain’s racing car industry, Scott Russell is not located in the Midlands or in the South, but is hidden away in the old Lancashire textile town of Rochdale, a fact which accounts, in part, for the low public profile of the firm. The company was started 24 years ago by Al Melling and derives its name from John Scott Russell, the man to whom Isambard Kingdom Brunel turned when he needed an engine built for the SS Great Eastern. That Melling should choose to honour one of Britain’s first engine builders, instead of using his own name, is an indication of the self-effacing nature of the man, as well as the breadth and depth of his engineering knowledge. Melling read Mechanical Engineering at University, taking a degree from Manchester/Salford in 1966, and has been involved with the design and development of high-performance engines ever since.
Melling is an engineer in the Keith Duckworth mould. He has a fertile and lively mind and radiates an almost boyish enthusiasm for out-an-out racing engines and for simple but elegant solutions to complex design problems. There is another similarity; each possesses a high degree of analytical ability and a desire to reduce technical or design problems to expressions which can be represented mathematically. Only after a vast number of calculations have been completed can design work (as we think of it) commence. Conversation with Melling is punctuated frequently by his resort to the calculator and by sketches drawn on whatever writing surface is handy — be it the back of an envelope, the table linen, or the table itself.
Scott Russell is a small company, no more than a dozen at full strength, headed by the sole proprietor, Margaret Brierley, who looks after the financial and management side of the business, though one suspects somewhat reluctantly for racing is what really interests her. Her fascination with automobiles and racing began early, and as a child she learned to recognize most cars by their sound. In her early teens she was taken to a race meeting at Oulton Park and was smitten immediately and irrevocably by the racing bug.
Over the last two decades, Scott Russell has done a wide variety of consultancy work on racing engines for cars and motorcycles. Much of the company’s work remains on the ‘secret list’ hidden by ‘confidentiality’ clauses which well-known firms in Europe, America and Japan write into consultancy contracts. But from various sources, it is evident that the range of consultancy work undertaken by them has been wide. For example, it is common knowledge in the racing world that Scott Russell has done research consultancy development work on Grand Prix engines for a leading Japanese manufacturer of racing engines. Other companies in the Grand Prix world have also sought their help. Leyton House, for example, are but one marque who have benefited from Scott Russell’s engineering analysis, design studies, and component engineering and performance testing, and in Group C racing, much experimental and analytical research was done on racing engines for Jaguar. Melling, for example, made calculations on four-valve heads for the Coventry firm’s production-based 7-litre V12 engine. By his calculations an engine with 4-valve heads should produce 800 bhp; when Jaguar did produce such an engine, it actually developed 796 bhp. Now consultancy research and experimental work is being formed on leading F3 engines, such as those derived from VW and Renault production car units.
Press reports have also confirmed that Scott Russell did extensive work for General Motors on projected engines for use in Formula 3000 and Formula One. The still born Formula 3000 engine was a 90 degree V8 using very highly modified 16-valve Family II cylinder heads. The Formula One engine was a completely fresh design, and it is a pity this innovative powerplant was shelved as a result of personnel and political changes within GM, At the time of cancellation, all design studies, calculations, and engineering drawings had been completed, as well as the manufacture and testing of components critical to the engine’s performance. Gasflow and combustion calculations put maximum power at 693 bhp at 12,300 rpm. The engineering drawings for this engine reveal a remarkable design, a bold and sophisticated solution to the new Formula’s challenges.
At first, a V10 engine configuration was considered, but on reflection this looked an unhappy compromise; it would not have the compactness of a well-engineered V8 nor the power potential of a good V12. Like Duckworth and Geoff Goddard of Cosworth, Melling thinks the V8 configuration is attractive with its inherent compactness and good torque characteristics; he can see why they chose this configuration for the Ford HB engine. In his view, a good V8 may be superior to a V12 of conventional arrangement.
However, after a complete analysis of various configurations, Melling settled on a V12, but a very unconventional one. By careful and innovative design, he was able to overcome many of the disadvantages usually associated with V12s. For a start this V12 engine is very wide-angled with the cylinder banks opened up to 165 degrees. This means that the unit’s profile is so low that it doesn’t contribute to drag inducing frontal area; in effect the crankcase hides behind the driver and the cylinders and heads are low enough to be masked by the car’s side radiators. The wide angle also gives the engine a very low centre of gravity. Design studies, in fact, began with a flat twelve engine, ie, a 180 degree configuration, in the quest for a low centre of gravity. However, after consultation with chassis designers, the cylinder banks and heads were raised (7½ degrees each) to provide just enough room for the exhaust pipes to pass underneath while still maintaining a low centre of gravity.
Normally V12s are comparatively long engines. For example, the Lamborghini V12 is 720mm (incl clutch) in length, the new Yamaha is 725mm long, and the Chiti/Subaru was a cumbersome 744mm. Melling’s V12 measured only 600mm in length, almost exactly the same as the Honda and Renault V10s and only 5mm longer than the Cosworth V8. Because greater gasflow and better combustion were anticipated, cylinder bores could be smaller thereby reducing engine length quite substantially. Great efforts were also made to keep the overall length of the engine/transmission package to a minimum. By opting for a wide angle V12, sufficient room was left between the cylinder blocks to mount the transmission above it. The gearbox rests over the rear six cylinders and is driven from the centre of the crankshaft by gears machined in the crankshaft webs.
In similar fashion, the cylinder heads of Melling’s design show marked originality. Four valves per cylinder are used with the valves arranged in a narrow ‘V’ of no more than 18 degrees included angle. Nothing terribly new there, but considerable effort has gone into making the heads as compact as possible. For example, cooling of valve guides etc, is done by oil, thus eliminating water passages and the space they normally occupy. The use of finger tappets also contributes to smaller cylinder heads and reduces lubrication needs and friction and pumping losses.
One of the most distinctive features of Melling’s Formula One engine is the design of the intake ports. They are bifurcated, somewhat reminiscent of the type used by the Fath/URS championship winning sidecar motorcycle engine of the 1960s, but distinctive in several ways. In Scott Russell’s design, four-valve heads are used so that for each cylinder there are two intake valves and four intake ports; two intake ports emerge from between the ‘V’ of the intake and exhaust valves (as in the old BMW engine), and two more come out the side of the head in conventional fashion.
The shape and dimensions of these ports are critical; Melling spent months at the computer working out the optimum design. The benefits of the bifurcated system derive from two effects. First of all, the combined gas-stream spreads more completely around the circumference of the valve head so that all potential valve-lift area is used. As a consequence, a greater amount of air/fuel mixture can be brought into the cylinder. The second advantage is more subtle and results in a better mixing and distribution of the fuel. The direction and high velocity given the incoming charge by these two small ports (each with its own injector) cause the two gas-streams to collide in a quite violent way imparting enough energy to atomize fuel droplets resulting in a more homogeneous mixture and consequently better combustion.
From the above description of the port/ head design of the Scott Russell Grand Prix engine, it is clear that much research and experience has gone into gasflow and combustion. This is the firm’s main area of specialization. Indeed, with characteristic modesty, Melling admits to being little more than a ‘burn’ man, ie, an engineer whose expertise centres on the combustion process. DDH