Ford Introduces New Duratec Sci Engine With Unique ‘smart Charge Injection’
Ford today revealed plans for the production of a new 1.8-litre Duratec SCi engine featuring direct petrol injection for improved fuel economy and lower emissions.
Named for its Smart Charge injection system, the new Ford Duratec SCi engine promises reductions in fuel consumption of between 6 and 8 per cent in real-world driving, along with increased power output and improved refinement. The all-aluminium engine is derived from Ford’s Duratec family of in-line four-cylinder petrol engines that power the Ford Mondeo.
Ford is introducing the new Duratec SCi engine at the 24th International Vienna Engine Symposium (24. Internationales Wiener Motorensymposium 2003, 15-16, May 2003).
Prof Dr Rudolf J Menne, Ford of Europe’s director of engineering for petrol engine development, led the Ford presentation at the Vienna symposium. He commented: “Our belief in developing the first-ever Ford production direct-injection petrol engine was that existing direct injection technologies had yet to deliver fully on their promise. Therefore, our clear focal point was to optimise for improved fuel economy across a much broader range of operating conditions with the new Duratec SCi.”
The new Duratec SCi uses less fuel, especially under low engine speeds or low load conditions, which makes it ideal for improving fuel economy in everyday, real-world driving. Similar to a common-rail direct-injection diesel engine, a direct-injection petrol engine injects fuel directly into the combustion chamber instead of into the intake port.
In order to enhance real-world fuel economy further, the Duratec SCi is combined with the new 6-speed MMT6 gearbox, which offers a higher-ratio top gear. This smart combination of technologies offers excellent performance feel and extremely comfortable and fuel-efficient cruising on highways and motorways.
Direct-injection petrol engines have especially low consumption levels during lean-burn operation, such as occurs in idling or moderate acceleration, when only a part of the combustion chamber is filled with gas-air mixture. Ford engineers, working to extend this benefit over a broader range of loads and engine speeds, developed the engine’s SCi (Smart Charge injection) technology.
“Normal petrol engines are more powerful than they need to be for operating at typical real-world driving conditions,” explained Menne. “Under these load and speed conditions, the engine uses a large proportion of fuel to overcome air resistance in the intake manifold caused by the load control via closing the intake throttle. The engine has to breathe against low pressures in the intake manifold, which causes pumping losses to go up and fuel consumption to increase.”
The Duratec SCi’s fuel injection system offers a smart way to overcome this throttle effect in low load conditions. Using lean-burn stratified smart charge in the combustion chamber, it is able to function almost unthrottled in a wide range of engine speeds and loads, making it much more frugal in its use of fuel.
Through this careful control of the flow of gases entering through the intake ports by swirl control valves, and the precise delivery of fuel into the asymmetric bowls in the piston crowns, SCi places a small, combustible gas-air charge in the combustion chamber so that it is situated near the spark plug at the point of ignition. The surrounding area within the combustion chamber is filled with either non-combustible mix or residual emission gas.
This results in efficient combustion with a reduced amount of fuel while producing enough energy for cruising or moderate acceleration. This extends the benefits of lean-burn operation to about 50 per cent of the engine’s full load capability and 60 per cent of maximum engine speed.
Careful optimisation of this characteristic by Ford engineers has delivered the Duratec SCi’s real-world fuel economy performance. A side benefit of this efficient combustion system is extremely stable idle operation and low overall vibration levels which could set new standards for engines of this size.
The special injection system for Duratec SCi was developed in close cooperation with Robert Bosch GmbH. It features a high-pressure injection pump powered directly by an engine intake camshaft.
The 130-PS, four-valve aluminium Duratec SCi engine features a number of technical differences versus the conventionally fuel-injected, 125-PS 1.8-litre Duratec HE engine. In addition to the swirl-control valve manifold, they include:
· Fuel injection nozzles which operate directly into the combustion chamber rather than into an external intake port.
· Specially designed pistons that feature asymmetric recesses, or bowls, to keep the stratified charge of fuel close to the spark plug. This unique design is critical for achieving ideal combustion efficiency under lean-burn stratified conditions.
· The injection system, similar to that of a diesel common-rail system, achieves fuel pressures up to 120 bar, contributing to the delivery of highly precise injection pulses.
· A complex exhaust catalyst system (EU Stage IV), which includes two three-way catalytic converters plus an additional DeNOx catalytic converter for robust emission control also under stratified lean operation conditions.
· High-energy direct-fire ignition with coil-on-plug technology and four-electrode surface-gap spark plugs, designed especially for efficient stratified combustion.
This new 1.8-litre Duratec SCi engine will make its production debut in the Ford Mondeo later in 2003. Direct petrol injection is another of the key technologies introduced as part of Ford’s commitment to deliver 45 major product actions in the five-year period from 2000.
“Ford’s first production Duratec SCi engine will offer customers an attractive alternative to conventional diesel and petrol powertrains,” Menne said. “It really combines the benefits of both – low fuel consumption and greater comfort combined with responsive power and excellent driveability.”