How does the Ford Fusion EcoBoost engine work?

EcoBoost Engine Animation

EcoBoost is the global marketing name for the Gasoline Turbocharged Direct Injection (GTDI) engine. This engine incorporates variable valve timing, direct fuel injection, and turbo-charging demonstrating a 20 % to 25% fuel efficiency, whilst simultaneously providing a greater power output, and approximately 15 % lower CO2 emissions.

So what exactly is unique about the engine that you will not find anywhere else? Ford describes a small part of this innovative technology as using “Direct Fuel Injection”. Invented and used by Jonas Hesselman in 1925, it was refined and improved by the Ford Motor Company in the 1970s.

Direct Injection

A conventional car engine block that burns hydrocarbon fuel has four strokes known as induction, compression, power, and exhaust. Induction is the only stage when a mixture of air and fuel enter the cylinders through the intake intake port valves. However, in an EcoBoost engine with direct fuel injection system, the fuel injects directly into the cylinders via a dedicated fuel rail line at approximately 2200 psi forming a finely atomised spray. A pump injects the fuel at a high pressure, and it may enter the combustion chamber during any stage of the 4-stroke cycle. This method of directly introducing the fuel produces a bigger “bang” during the power stroke for a lean burn.

Injected at pressure, the vapour settles at the centre of the cylinder close to the spark plug, whilst an envelope of air develops around it. During the power stroke when the fuel ignites, the air surrounding the fuel behaves as a cushion and prevents the heat energy from escaping through the cylinder walls. This helps to keep the cylinder walls cooler and prevents the fuel from pre-igniting causing engine knock.

Variable Valve Timing

In a conventional engine, the intake and exhaust valves operate in opposition, because when the intake valves are open the exhaust valves are closed. This ensures the new fuel does not mix with the exhaust gas, and all the exhaust gas expels from the output port. However, exhaust gasses usually contains un-burnt fuel, which usually goes to waste and adds to pollution.

In an engine with variable valve timing, it is possible to adjust the timing so that both the intake and exhaust valves remain open for a fraction of a second. This overlap has the effect of mixing new fuel with some of the exhaust. Since the exhaust also contains some un-burnt fuel, the engine provides greater torque output and produces lower emissions.

The Ford Engine Management System (EMS) can also vary the timing of the fuel injection to achieve an ultra lean burn. A lean burn usually occurs when the ratio of air to fuel is 65:1.

Turbocharger

Turbocharger

The turbocharger is a device, which extracts energy from waste exhaust gasses and converts into useful mechanical energy. In a conventional car, this energy usually goes to waste through the exhaust; however, the turbocharger is able to make use of this energy. The exhaust gasses drive the turbine blades of the turbocharger, which makes the engine more efficient compared to conventional engines.

As shown in the diagram above, the shaft of the turbine blades connects to the compressor. The compressor section, shown in blue, sucks the air from outside and forces it back out at a great pressure. This highly pressurised air feeds the cylinders of the main engine to produce a bigger bang. This is because compressed air contains a larger amount of oxygen, which behaves as a catalyst, and when the fuel ignites during the power stroke, there is a greater energy output.

By using a combination of direct fuel injection and pressurised air from the turbo charger, the EcoBoost engine is one of the most efficient engines ever produced in the automotive industry.

1.0 Litre Three Cylinder Turbo

The EcoBoost 1.0 litre three-cylinder turbo engine is an extremely popular engine due to its high fuel efficiency. It is an inline three-cylinder turbo petrol engine with direct fuel injection and Ti-VCT transverse. There are two versions of this engine with different power output, 100 PS (73.5 kW), and 125 (92 kW).

100 PS 125 PS
Displacement 999 cm3
Cylinder Head Cast Aluminium
Camshaft drive Belt-in-oil
Compression Ratio 10:1
Max Torque 170 Nm 200 Nm
with over-boost
Valve 4 valves per cylinder
Transmission iB5 B6
Management Bosch MED17 with CAN-Bus
Emission Level Euro Stage 5
Bore 71.9 mm
Stroke 82.0 mm