Ever since the 1.0-litre EcoBoost turbocharged three-cylinder petrol engine made its debut in the Fiesta, Ford has been persistently spreading the zingy little motor to - usually larger - cars like the Focus and even the Mondeo.
There are constraints, of course, as the small capacity and forced induction can only produce so much power before being pushed to the point of gross inefficiency and unreliability, which is why Ford has larger plans for the larger 1.5-litre EcoBoost three-pot that will be powering the upcoming fast ST version of the 7th-generation Fiesta.
In the hot hatch, it’s expected to produce upwards of 150kW, and will mark a critical point in Ford’s powertrain strategy as it plans to swap out the many of their more traditional 4-cylinder units with these smaller engines. Additionally, in an interview with Autocar, Joe Bakaj, product development chief to Ford of Europe, said that these engines are unlikely to increase in displacement.
Power, too, is at a satisfactory level, but they believe this isn't presently the best way to improve performance and efficiency. Therefore, decreasing weight stands as a higher engineering priority than increasing engine output.
He says that 500cc per cylinder creates an optimum thermal efficiency balanced with expectations of power output, fuel consumption, and combustion emissions. This leaves room to interpret that, should Ford need a larger engine, it would be in those increments: such as a 2.0-litre four-cylinder, 2.5-litre five-cylinder, or 3.0-litre 6-cylinder.
In that case, the current 1.0-litre EcoBoost engine doesn’t quite fit the mould, and should have one cylinder removed to fit into the specific 500cc division. However, overlooking that, the short term reality is that all of Ford’s mainstream cars will be offered with three-cylinder engines, positioned within popular variants to make them the bulk of their sales.
The Blue Oval has also found that their new 10-speed automatic transmission, developed together with General Motors, is a particularly good fit for this new breed of engines, providing better low-end assistance over a wider spread of the power band, especially when contrasted against the Getrag-sourced dual-clutch automatics they were using some time ago.
The BMW Group has also warmed to using turbocharged three-cylinder engines in recent years, also displacing 500cc per combustion chamber, a block that could be crudely summarised as their B58 3.0-litre straight-six cut in half. Such a 1.5-litre unit is powering versions of their 3 Series (318i), several MINIs, and is found mounted in the midsection of the i8 hybrid sports car.
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