The water pump revolution
With the start of the AMA Supercross, a new technology has appeared on a number of machines. These are equipped with an electric water pump to replace the traditional mechanical version.
Until now, the coolant in a dirt bike was pumped using a mechanical water pump driven by the engine itself. A paddle wheel (impeller) rotates in a pump chamber to force the fluid through the engine and radiators to maintain the temperature at a certain level.
Hot, hot hot
The fact is that modern four-stroke machines are close to the boiling temperature on heavy circuits where a lot of traction is required on the rear wheel. Now take the circuit in Lommel. A number of well-known brands do not let the pot boil over or just barely boil over in such a heavy circulation. The cooling capacity has therefore reached a point where the limits have been reached.
Who does it?
It was Honda that first used an electric water pump on Jett Lawrence's HRC machine. That was halfway through the AMA Outdoor season last year. A similar system showed up last weekend during the first AMA Supercross in Anaheim. There were the machines from HRC Honda, Star Racing Yamaha, BarX Suzuki and MotoConcepts Honda with an electric water pump at the starting gate.
The advantages
It goes without saying that driving a mechanical water pump requires energy. It's part of the driven mass and so you lose power to drive that impeller and move the coolant around. So you already gain that by using an electric pump that only needs a little bit of electricity to work.
However, the main reason for using an electric water pump is the cooling capacity limits reached. Due to the high power of a modern four-stroke, more and more cooling capacity is required. You can achieve this by installing larger radiators, but from an ergonomic point of view there is hardly any room for them. You can also increase the flow rate of a mechanical water pump (remember the water pump kits from Boyesen), but more flow also means more driven mass and therefore an additional loss of power. An electric pump has a higher flow rate without affecting the motor power. So you gain power, reduce the driven mass, there is better throttle response and the average temperature would drop by about 20 degrees Celsius.
Are there also disadvantages?
Not really. Of course there must be electricity, but it is present on every dirt bike with injection. And installation can be a difficult job because the water pump has to be accommodated in the already tight space above the engine block. An electrical system naturally has its specific sensitivities. We are thinking of a possible DNF due to poor contact in the wiring. As always, good maintenance is crucial for trouble-free driving.
What do we really think?
That every serious dirt bike manufacturer will bolt this item onto their production models soon. This is because the benefits are great and the cost of an electric water pump is not such that it would dramatically increase the total price of a dirt bike.
Photos: VitalMX, Rocky Mountain ATV
Tekst: Danny Hermans
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