Engine downsizing is all the rage, and BMW is the latest automaker to unveil tiny three-cylinder engines. The automaker revealed plans for gasoline and diesel versions of a turbocharged 1.5-liter inline-three engine that could reportedly be used in future Mini and BMW cars.
The basic idea is that a smaller engine with fewer cylinders weighs less and has less internal friction, both of which help fuel economy. Yet despite the reduce cylinder count, BMW says the new engine provides lots of low-end torque, a “vivacious” engine note, and smoothness to rival its larger engines. Special balance shafts and dampers are used to help quell the vibrations that are typical of three-cylinder engines.
The new 1.5-liter is part of BMW’s TwinPower engine range, which is based on individual cylinders displacing 500 cc. That explains why the TwinPower four-cylinder in the BMW 328i displaces 2.0 liters, and why the six-cylinder engine in the BMW 335i displaces 3.0 liters. A three-cylinder version, it follows, measures 1.5 liters.
BMW expects each cylinder in the gasoline TwinPower engines to produce 40-74 hp and 44-59 lb-ft of torque — meaning a three-cylinder should be rated for 120-222 hp. Diesel TwinPower engines, meanwhile, are expected to offer 27-60 hp and 55-81 lb-ft, for totals of about 81-120 hp in a three-cylinder configuration.
BMW has so far been coy about which vehicles will receive the three-cylinder engines, but Autocar reports the first application will be the next generation of the Mini Cooper. The car’s small size and low weight make it an ideal platform for a small 1.5-liter turbo-three engine. After that, the mills could be used in European versions of the 1 Series and 3 Series, as well as in a future front-wheel-drive BMW.
Finally, the small engine will likely serve as a range extender in plug-in hybrid BMW models, like the upcoming i8 sports car. We previously reported that BMW’s plant in the U.K. would soon start building a 223-hp, 1.5-liter turbocharged three-cylinder engine for use in the i8.
BMW also touted a new feature called Predictive Power Management, which would use information from the navigation system to help the transmission select the appropriate gear. If the car “knew” the driver was approaching a sharp bend, steep hill, or intersection, it could automatically choose a gear that is both efficient and provides adequate acceleration.
Several other automakers have toyed with switching to three-cylinder engines to save fuel. Ford announced that it will install a turbocharged 1.0-liter inline-three engine in the 2014 Fiesta. The engine also will be offered in the European-market Focus.
Sources: BMW, Autocar