how much hp does power steering cost?
1 horsepower is equal to abou 750 watts of electric power. Assuming the alternator is about 90% efficient, and running at 14.5v, a 45 amp draw from the alternator requires 1 engine hp. So, running 30 amp electric fans uses about .66hp, running an electric water pump (about 10 amps I think) uses .2hp. If the power steering actually needs 2hp to run, it would have to pull 90 amps off the alternator to turn it. However, that 2hp was probably at like 5500rpm, but the pump only needs to turn about 2000-2500rpm, so the power requirements would be way less, like 20-30 amps at most.
I think the major advantage to electric drive, as someone else mentioned, is you can run the parts at their optimal RPM, so at high RPM you still only require enough power to run the parts at low RPM.
There is one thing about mechanical fans that's kept me wondering. The power loss due to a mechanical fan is not to spin the fan, but to move air. It takes very little power to spin the fan (imagine if the blades were flat), so the of the 10hp loss from a big belt driven fan, I'd say 9.5hp goes to actualy moving air. Now, if a BIG electric fan pulls a 30 amp load, that means it is only consuming about .7hp of energy, .7hp of moving air, compared to 9.5hp of moving air. To me this means that if you are having cooling problems, the LAST thing you want to do is swap out your belt driven fan for an electric. Any thoughts?
'97 F250HD 4x4 460; '85 Ranger, 350hp 289, T5, email@example.com
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