|The new MINI Cooper.|
BMW has provided some initial detail on the two new, more fuel-efficient engines to be featured in the latest generation of the MINI. Upon their arrival on the market in late 2006, the new MINIs will initially offer two versions of a 1.6-liter engine—one naturally aspirated, the other a turbocharged direct-injection unit.
These will be augmented by a new 1.4-liter gasoline unit and a turbodiesel, both arriving in the first half of 2007.
The 1.6-liter naturally aspirated unit in the MINI Cooper develops maximum output of 88 kW (120 hp) at 6,000 rpm. Engine torque reaches 140 Nm (103 lb-ft) at just 2,000 rpm, peaking at 160 Nm (118 lb-ft) once the engine reaches 4,250 rpm.
The four-cylinder engine features fully variable valve control based on the BMW Group’s VALVETRONIC valve management system, which adjusts intake valve lift and opening times within fractions of a second to current power and performance requirements.
In addition to variable control of valve lift on the intake side, valve timing may also be changed in both the intake and outlet stroke, optimizing the torque curve and the development of engine power in the process. The result is not only powerful torque at low engine speeds, but also high power at high speeds.
Together, these two technologies reduce fuel consumption, depending on the route the driver is covering, by up to 20%, with fuel consumption in the combined EU cycle down by approximately 16% to 5.8 l/100km (41 mpg US) from 6.9 l/100km (34 mpg US). CO2 emissions on the MINI Cooper are now 139g/km.
The turbocharged version, used in the MINI Cooper S, develops maximum output of 128 kW (175 hp) at 5,500rpm. Peak torque of 240 Nm (177 lb-ft) is maintained consistently between 1,600 and 5,000 rpm. When accelerating all-out, torque is raised to an even higher level of 260 Nm (192 lb-ft) by briefly increasing charge pressure (overboost).
Intake air for the direct-injection engine is pre-compressed by a twin-scroll turbocharger complete with intercooler. With this new technology, the ducts of two cylinders at a time are separated from one another in the exhaust gas manifold and in the turbocharger itself.
This particular configuration enhances turbocharger response and almost completely eliminates the usual turbo gap, according to BMW, which claims that the 1.6-liter turbocharged engine is very similar in its response and behaviour to a much larger normal-aspiration power unit.
Two overhead camshafts operate the four valves per cylinder. The camshaft on the intake side comes with infinitely variable phase adjustment setting valve timing to current power requirements and optimizing both engine output and torque on minimum fuel consumption and emissions. The outlet valves, in turn, are filled with sodium in order to set off the higher temperature loads typical of a turbocharged engine.
Combined EU cycle fuel consumption for the MINI Cooper S have dropped 25% to 6.9 l/100km (34 mpg US) from 8.6 l/100km (27 mpg US). CO2 emissions on the MINI Cooper S are now 164g/km—a reduction of 43g/km.
Both engines use a volume flow-controlled oil pump driven by a chain and limited in its delivery volume as of a certain, predetermined pressure level. This reduces the power required for driving the pump and cuts back fuel consumption by approximately 1%.
The on-demand water pump in the coolant circuit is only activated when the engine has reached its regular operating temperature. This helps to save fuel in the warm-up phase, and the catalyst is able to reach the temperature required for optimum operation with an optimum effect at an earlier point.
The alternator and air conditioning compressor, in turn, are driven by one single poly-V-belt. The water pump is driven by a friction wheel.
BMW will issue full specifications and technical details in September at the Paris motor show.
|1.6-Liter Engines for New MINIs|
|MINI Cooper||MINI Cooper S|
|Engine||Naturally aspirated||Turbocharged, direct injection|
|Peak Power||88 kW (120 hp)||128 kW (175 hp)|
|Peak Torque||160 Nm (118 lb-ft)||240 Nm (177 lb-ft)|
|Fuel Consumption||5.8 l/100km (41 mpg US)||6.9 l/100km (34 mpg US)|
|CO2||139 g/km||164 g/km|