Scheme 706
Scheme 707
In 1996 BMW Group and Chrysler entered into a joint venture to design and construct a small gasoline engine with a cylinder displacement of 1598cc. The venture would provide an engine suitable for both car manufacturers in terms of power output and compliance with world emissions. The venture is known by on of the following names
Pentagon or Trident. In addition BMW required a high power derivative for the MINI COOPER S.
The MINI COOPER (COOPER S) engines are a product of this venture.
The MINI COOPER (COOPER S) is a front wheel drive vehicle with the engine mounted transversely across the car.
Cooling System Operation
When the engine is cold the thermostat is closed, preventing the coolant from circulating through the radiator. Coolant is able to circulate through the heater core, expansion tank, and on the MINI COOPER S, the oil cooler.
The MINI COOPER S has a pressurized expansion tank, and allows coolant to enter the top via the heater core pipe, and exit the bottom of the tank to join the heater core return pipe.
Scheme 708
Scheme 709
As the coolant temperature increases the thermostat gradually opens. This allows a bleed of coolant from the bottom hose into the cylinder block via the coolant pump, and allows hot coolant to flow to the radiator via the top hose. The flow of hot and cold coolant is balanced to maintain the optimum engine temperature. When the thermostat opens fully, the full flow of coolant passes through the radiator.
Operation
When the compressed air mass leaves the outlet of the supercharger, the molecules of air are tightly packed together which generates heat. The air is forced into the inlet of the intercooler and is passed through many elongated tubes.
The ram air effect takes place as the vehicle moves forward and outside air passes externally over the elongated tubes cooling the compressed charge sufficiently before leaving the intercooler.
Supercharger Operation
The supercharger is a positive displacement pump. Its purpose is to increase air pressure and density in the intake manifold. The supercharger is matched to the engine by its displacement and belt ratio (driven from the crankshaft). The concentrated charge of air provided by the supercharger results in a more powerful combustion stroke in the engine's cylinders, resulting in improved performance over non-supercharged engines.
The supercharger incorporates a specially designed bypass valve. This is actuated by a vacuum pipe near the throttle body and re-circulates the supercharger air when boost is not required. During typical driving conditions the intake manifold is under pressure for only 5% of the time. For the remaining time the intake manifold is under vacuum (negative pressure), allowing for better fuel economy and a quieter ride.
Inside the supercharger the helix angled rotors and specially designed inlet and outlet port geometry reduce pressure variations. This results in a smooth discharge flow and a lower level of noise during operation. The way in which the ducting to and from the supercharger is mounted also plays a major role in reducing noise.
