Quote:
Originally Posted by serialk11r
mja1, sure on the street, if you're running electrical devices off an alternator, then there's not much of a benefit since the engine only needs to turn say 3000rpm on the street. But once you start using the higher revs say in performance driving, or if you have a set up that gets electrical energy from a more efficient source, then an electric pump makes quite a bit of sense. Since alternators these days attempt to generate more energy under favorable circumstances, the efficiency loss is mitigated somewhat.
I suspect that under low load like on the highway the pump is likely spinning a little too fast already, and since pumping power is approximately the cube of speed, you only need it spinning <30% faster than it needs to before an electric pump spinning at the appropriate speed with 50% efficiency breaks even.
I don't think anyone is talking about turning the pump off, just reducing the speed.
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The only reason I could see an electric pump being greatly beneficial is on a drag car that has no alternator, or low amp one. Something that spins over 7000-8000rpm where we'd have cavitation of a traditional mech. pump. If we're talking about a circle track or track car, above 3000-4000 rpm the mechanical pump will outflow an electric, at the same gpm the mech pump will have a higher pressure.
Fuel efficiency and freeing up hp/engine efficiency - two different subjects, which the max hp freed by this would be 5-10 hp over an inefficient mech pump, less so vs an efficient one, which isn't going to account for any noticeable acceleration increase. The biggest problem we face with using an electric pump for 'fuel efficiency' on something with an alternator is we're converting mechanical energy to electricity back to mechanical when using an alternator with electric pump. It really doesn't matter how efficient the alt and electric pump are, it will be very close to an efficient mech pump. The only way to make up for this is to turn off the pump or greatly reduce the voltage/speed of pump like you say, but now we're not only flowing less gpm at highway cruise or performance driving we're doing so at much less pressure via the nature of the electric pump does not have nearly the same torque. Meaning the engine will be running at hotter temps. We know that the engine can handle this and we think it will result it better mileage. But everything changes when an ECU is involved, especially with engine temps. But I'm just rambling, if people want to try it out go for it it'd be nice to see results.