MINI One D | Part Four

Diesel Is Not A Dirty Word

Second-generation common rail diesel technology incorporates intelligent-computer controlled fuel injection, feeding fuel at exactly the right time and under extremely high pressure directly into the combustion chambers. Serving as a pressure reservoir, the common rail supplies fuel to the injection jets, a high performance pump which makes sure that the fuel in the pressure reservoir remains under high pressure at up to 1600 bar (first generation was only 1,350 bar). This high pressure serves to atomise the fuel into extremely fine particles, ensuring a clean combustion process free of any residues.

Electronic engine management controls the timing and duration of both the pilot and main injection process. With the pilot injection feeding a small amount of fuel into the combustion chambers prior to the main injection, the fuel/air mix burns more smoothly than with a conventional diesel engine. The smoother rise of pressure in the combustion chambers helps to keep the combustion process noise down to a minimum and also sees a reduction in emissions.

As a result of this advanced technology and the oxidation catalytic converter, the MINI One D outperforms the EU 3 emission standard. The MINI One D is also capable of running in sulphur-free fuel enabling further reduction of soot particle formation.

Under Pressure

The turbocharger in the MINI One D has been selected to provide the very best in power and life of service.

Compression of fresh air drawn into the engine increases output significantly: the higher the pressure at which the fresh air is compressed in the cylinders, the higher the output developed by the engine and the thermal and mechanical loads acting on the drive system.

The compressor runs at speeds of up to 225,000 rpm in order to compress the fresh air to an overpressure of 1.2 bar. A side effect of compressing air in the turbocharger is that it warms up and as a result expands, reducing the efficiency of combustion. To combat this problem, the intercooler cools the air before it reaches the combustion chamber, making it denser and therefore richer in oxygen. As a result it is more combustible and increases performance whilst reducing consumption. The intercooler is fitted next to the engine radiator and takes its supply of fresh air through the radiator three bar front grille.

Raring To Go

The turbocharger breathes life into the MINI One D engine with instant effect ensuring that there is no delay in the power reaching the driver. The engine is able to build up two thirds of it’s maximum torque (120 Nm) at 1500 rpm peaking at 180 Nm at 2000 rpm, which allows the same sort of sporty driving usually associated with petrol models. The engine’s smooth delivery of power and quick response is ensured by the electrical transmission of signals from the gas pedal to the power unit (ie. electronic throttle). Maximum output of 75 bhp is reached at 4000 rpm.

The addition of ASC+T as standard on the MINI One D ensures that the power is transferred safely to the road, especially in slippery conditions. Optional Dynamic Stability Control (DSC) increases safety to an even higher standard by applying the individual wheel brakes as required if the vehicle becomes unstable whilst accelerating or when pushing through a sharp bend.

Even on chilly days the MINI One D will be raring to go thanks to its quick start pre-heater system. When temperatures drop really low, the MINI One D refuses to be beaten – an additional electrical heater ensures the warmth and comfort of the passengers inside.

continues... | Part Five
Published 1 June 2003 Melanie Carter

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