1964-1974 [Subscribe to Daily Digest] |
Yes a variety of systems are offered for drag cars. Many of them bolt up in the stock pump position so are unique to specific engines. The trouble with them as I understand is that they are not constant-duty pumps and therefore unsuitable for street cars.
The controller technology is routine and easily adapted to an electric water pump. Two types are used: Pulse-width modulation is used to optimize the speed of electric fuel pumps, the circuitry for this is contained in the engine control module. And two-and three-speed electric cooling fans are generally controlled by mechanical relays tied to a temperature sensor. The higher power requirements of fans probably make this technology economical. Water pumps can easily be controlled by either method. The control circuitry for electric motors on hybrid or all-electric vehicles is similar and obviously requires high power capacity and high reliability. Just because D-C didn't make a reliable controller doesn't mean it can't be done.
The pump on my Saab has a 3-speed setup involving two temp sensors with different set-points and three standard Bosch relays. As an experimental one-off it is a little more cumbersome than one would design for production, but works fine.
Electric water pumps will definitely improve power to the wheels by reducing a parasitic drag, and/or fuel economy depending on how you drive. The gain in fuel economy is probably in the range of tenths of a MPH, but every little bit helps. I think the D-C literature claims "up to" 5-8HP, which may be considerably inflated. But even a 1HP improvement on a 65HP V4 engine is a 1.5% improvement of power to the wheels, that is no longer needlessly spinning the water pump. For comparison, a Ford engineer working on 42V electric accessory design told me that an electric power steering pump could yield improved fuel economy in the neighborhood of 1/2MPG. I would think an engineer would absolutely kill for that kind of benefit, that is a big increment for a single component.
posted by 198.69.25...
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