The E39 M5 Super Duty Cooling Kit... The alloy fan shroud and electric fan work in concert to provide maximum cooling efficiency by pulling 2070 cfm through the radiator core - even while sitting still if required by engine temperature. Simply hanging a fan on a core is inefficient as airflow must be directed through the entire core area, not just directly in front of the fan. The latter approach limits the effectiveness of the core. Essentially, it reduces the core size to the diameter of the fan. Not to mention the fact that hanging a fan through the core will eventually fatigue the cooling tubes and lead to failure.

The alloy shroud in combination with the electric fan creates a low pressure area behind the radiator in order to pull air through the entire core surface. (The front of the core is exposed.) The concept is a refinement of the BMW design. Our kit features improved sealing of the shroud and increased air flow without the parasitic drag of an engine-driven fan. We have also been advised by both customers and technicians that the engine fans are disintegrating at around 100k miles, taking out the cooling system and damaging the hood of the car. Our design incorporates a caged electric fan with a safety shroud and lighter weight individual fan blades. The result is improved safety and efficiency.

With regard to the expansion tank, we have been advised and personally experienced tank failure through rupture of the main expansion tank. Our thinking is that due to higher heat soak temperatures on V8 and V12 cars, the tanks are heated/ pressurized beyond their limits. As a result, we designed an alloy expansion tank with greater resistance to degradation caused by the more extreme temperature limits in V8 and V12 cooling systems. Our tank does incorporate some of BMWs features; e.g., we retain the original cap and the internal plumbing. The cap design is very clever: it facilitates the expansion and contraction of coolant, while at the same time offering an escape route for atmosphere and coolant when pressure in the system threatens passenger well being *** and cooling system integrity. The topping off process requires filling the tank until one half the level is maintained during the initial fill, then topping off after a driving cycle, once the cooling system is cold. As in all our radiators, the alloy construction of the radiator also improves efficiency through an increase of radiant surfaces and enlarged storage capacity.

With the 2 speed fan kit, the fan operates on low speed or high speed based on engine temperature. High speed comes on only when necessary. Running the fan through a resistor allows us to back the speed down when the extra volume is unnecessary, creating less wind noise.

* Otherwise, the heater core could rupture and spray coolant inside the passenger compartment.