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.