Changes are focussed on reducing exhaust emissions.
BMW has detailed the next-generation of its Efficient Dynamics engine family, which includes three- and four-cylinder petrol and diesel units. Among a raft of changes, improvements have been made for better fuel consumption, noise levels and pollution controls.
The engines will be used in a wide variety of models, across both the BMW and Mini brands. As such, they can be mounted longitudinally or transversely, depending on the application. It isn’t yet known when the new motors will be released, but the 2017 5 Series is expected to be the first recipient.
Petrol engines will receive a boost of seven horsepower and 15 pound-feet of torque across each level of tune available. As a result, the 1.5-liter, three-cylinder units will come with 103 hp or 115 hp. And the 2.0-liter, four-cylinder options will range from 149 hp to 234 hp. BMW promises fuel economy and emissions will improve by five per cent, as well.
Every petrol engine uses a ‘Twin Power’ turbo set-up, comprising high-pressure direct fuel injection, Valvetronic variable lift on the inlet valves, and Double VANOS variable valve timing on both the inlet and exhaust side.
The turbo itself has been relocated, along with the exhaust manifold, to sit within the cylinder head. Fuel pressure has been increased too, up to 350 bar, which BMW says allows more accurate fuel metering, in turn reducing pollutant emissions.
A new cooling system increases efficiency, as well, thanks to a twin-output coolant pump that sends separate flows to the engine block and cylinder head.
On the diesel front, BMW again promises a 5% bump in fuel economy and emissions levels across the board. No claims have been made about power increases, however all four-cylinder units will switch to the twin-turbo set-up previous reserved only for the most powerful engines.
Most of the focus, though, has been on reducing pollutant emissions. A new exhaust gas recirculation (EGR) system will scrub more harmful nitrogen oxide from exhaust gases than before and an additional selective catalytic reduction (SCR) system will further reduce NOx emissions in real world driving.
SCR uses a water-based urea solution called AdBlue, which is injected into the exhaust flow as needed and reacts with the NOx, breaking it down into harmless nitrogen and water.
Other changes include a higher-pressure common-rail injection system and an innovative ‘flared’ cylinder bore profile. According to BMW, it prevents the piston becoming loose at the top of the stroke, reducing noise, and creates less friction at the bottom of the stroke, improving efficiency.