Lucas fuel injection

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Complex problems often demand simple solutions. Ensuring that exactly the right amount of fuel reaches the right place at exactly the right time is a given in the computer age. Forty years ago, an integenius, all-mechanical item did the trick.

Some motorsport developments appear overnight and establish themselves as must-haves almost immediately. Others make a first appearance, stutter, and only fulfil their obvious promise second time around. Fuel injection was one of the false-starters. Originally introduced into Formula One in

the early 1950s, it only became a sine qua non a decade later. Once it had, one unit — the Lucas shuttle metering system — came to enjoy near total dominance, not least because Keith Duckworth selected it to fuel the Cosworth DFV. On the back of that remarkable engine, the Lucas unit reigned supreme in F1 — and a host of other formulae besides — until the turbos took hold in the early 1980s.

Despite this, Lucas isn’t the first name to spring from the pages of fuel injection history. MercedesBenz began to experiment with it on racing engines in the years immediately before World War II, for which it naturally turned to compatriots Bosch to supply the hardware. The system showed considerable promise and would probably have appeared on the formidable Type 80 LSR car, but war intervened. Bosch then gained further experience developing the system for the Luftwaffe’s aero-engines, work it had begun as early as 1930.

It’s no surprise, then, that when Mercedes returned to motor racing in the ’50s, it brought Bosch fuel injection along too. The first model to use it was the racing 300SL of 1952; two years later it also appeared on the W196 F1 car, the technical tour de force of its time. Not only did these cars boast fuel injection, but both used a high-pressure direct injection system in which the fuel was sprayed straight into the cylinder. Port injection — where the fuel mist is sprayed into the inlet tract, upstream of the intake valve(s) — remains the norm on both mad and track. The Bosch system used by Mercedes could be used in either mode as desired. Having made the comparison, engineers at Untertiirkheim chose direct injection; Vanwall, a later Bosch customer, opted for port injection.

A different system actually took to the grand prix circuits a year earlier, fitted to A-series Connaughts, but it was technically inferior. Originating in the USA, the Hilbom-Travers unit (developed by Stuart Hilbom in 1946 and in production since 1948) was a constant-flow system which — incredibly to our modern eyes — pumped fuel continuously into the inlet tract, at a pressure modulated by engine speed. Unsurprisingly, fuel atomisation was not its strong point as liquid fuel pooled behind the inlet valve, waiting to be admitted on the induction stroke, and neither was fuel metering since the amount of fuel injected depended on engine speed rather than load. Although the Connaughts enjoyed some success with it, that was due more to their use of the original Fl ‘rocket fuel’, nitromethane.

Other teams experimented with fuel injection during the mid-50s, but all were basking in the luxury of alcohol-blend fuels, which are notably tolerant of lax mixture control. Hydrocarbon fuels are not so forgiving, and when the sport’s regulatory body, the CSI, changed the fuel regulations for 1958, specifying 100/130-octane Avgas, fuel injection suffered a reversal. Vanwall modified its Bosch injection to cope — just — and won the 1958 constructors’ championship with it But from 1959 to ’61 the world championship was won by cars on carburettors, despite their poorer breathing and hesitant pick-up caused by fuel surge in the float chambers. If fuel injection was to prevail, something better was clearly needed.

That something — the Lucas shuttle metering system — arrived in 1962 on the new BRM V8. Originally developed late in the war for use on the Rolls-Royce Merlin, it had been experimented with on the Jaguar XK120C Le Mans car (along with an SU competitor) and eventually saw ill-fated use in the works Jaguar D-type of 1956. But it was only on BRM’s championship-winning engine, and then the Coventry-Climax V8, that it really came to prominence.

Lucas’s system was mechanical in that it incorporated no electronic control, but not in the sense of being like a rotary diesel pump or Bosch’s complex one-plunger-per-cylinder unit. Fuel pressure of about 100psi (6.9bar) was generated by an electric fuel pump, the mechanical action of the fuel injection assembly relating solely to the metering and distribution of the fuel.

Central to its operation was the shuttle itself; a small freely moving piston mounted within a rotating sleeve. The position of a control stop, which was adjusted via a cam, determined the distance the shuttle could move and hence the amount of fuel delivered; the rotating sleeve, driven at half or quarter engine speed via the camshaft drive or a flexible toothed belt, opened and closed ports in its housing to admit fuel from the pump and direct the metered charge to the appropriate cylinder. Opening an inlet port at one end of the sleeve forced the shuttle to eject fuel though the open outlet port at the other, while at the same time ingesting the next charge. Distinctive transparent nylon pipes — chosen because, unlike rigid lines, they were unaffected by engine vibration — carried the fuel from the distribution unit to the poppet valve injectors, located in the inlet tract of each cylinder. Mixture control was via inlet manifold vacuum, with correction for barometric pressure.

Although costly because of the precision machining involved, it was compact, reliable, accurate, much simpler to maintain than difficult-to-balance multiple carburettors, and released more power as well as saving fuel. In conjunction with the Lucas OPUS (oscillating pick-up system) contactless ignition, introduced later, it formed a complete fuelling and ignition package for high-performance sixand eight-cylinder engines, one which just about everyone in F1 came to use. Not until full electronic control of spark and spurt became possible in the early 1980s was it finally outmoded.

Inexplicably, Lucas made no marketing capital out of this success, right up until it ceased manufacture of the system in 1984, when the old Lucas Gas Turbine factory in Liverpool closed down. Next time you hear the old ‘Lucas, prince of darkness’ gag, you might want to enlighten its teller.

Thanks to Bob Blurton of BBI for his help in preparing this feature

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