BMW is planning to turbocharge all its future four cylinder petrol engines, according to new information from company sources.
The company will use four cylinder engines for outputs up to 241bhp under the plan. Above that level BMW will use its new-generation straight-six engine.
All the four cylinder turbocharged engines will be based on the same new-generation 2.0 litre aluminium block, with different power outputs delivered by using two different types of turbocharger and different engine management maps.
The new block gets a new type of cylinder lining, which sees iron sprayed on at a thickness of just 0.3mm, instead of using conventional 1.5mm thick cast iron liners.
The range-topping 241bhp version of the unit, which makes its debut this week in the X1 SUV, gets a double-sided 'twin scroll' turbocharger, double vanos variable valve timing and high pressure (up to 200 bar) fuel injection.
Lower-power versions of the unit will probably get a conventional single turbo.
Compared with the outgoing 2.8-litre six-pot unit, the '28'-badged four-cylinder engine which replaces it, offers a hike in torque from 229lb ft to 258lb ft, a cut in the 0-62mph by 0.7sec to 6.1sec and a reduction in CO2 output from 219g/km to 183g/km.
The new range of turbo fours are expected to debut in the forthcoming new-generation 3-series.