Fuel Pressure - What's Too High?
09-15-2005, 11:46 AM
#32
Chapter President
The RASP is a very small pump with a low output.......compare it to another engine-driven pump...the power steering pump : The hydro boost version of the Saginaw PS pump puts out 1500 psi max. and roughly 4-5 gpm....the parasitic loss to the engine with this pump is equal to roughly 5 hp - but only when the pump is operating at it's peak output. I highly doubt the RASP will put out anywhere near 5 gpm (300 gph) and at only 50 psi, this is 1/30th of the pressure of the PS pump. Some crude estimating when comparing parasitic loss of these two pumps would put the RASP parasitic loss at under 1 hp........ Hardly worth mentioning. As Hohn mentioned, this would likely be similar to the extra load the alternator would create when operating an electric pump. We would be splitting hairs to compare the difference, IMO.
09-15-2005, 02:36 PM
#33
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Originally Posted by HOHN
Source: Stephan Kondolay. I'm hesitant to say sources because 1) he didn't ask to be quoted, and 2) if someone doesn't believe me, they don't believe me. Anyone think the Kondolays know a little about diesel performance? I respect them for their honesty and willingness to shoot straight. so....
Anyway-- YES, the RASP does take some engine power to drive. But is it any less than the increased alternator drag required to power an electric pump??
The I think the electric vs mechanical is a non-issue with parasitic loss, as they're about the same and relatively insignificant, imo.
Your thoughts?
Anyway-- YES, the RASP does take some engine power to drive. But is it any less than the increased alternator drag required to power an electric pump??
The I think the electric vs mechanical is a non-issue with parasitic loss, as they're about the same and relatively insignificant, imo.
Your thoughts?
09-15-2005, 07:00 PM
#34
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Originally Posted by HOHN
Anyway-- YES, the RASP does take some engine power to drive. But is it any less than the increased alternator drag required to power an electric pump??
The I think the electric vs mechanical is a non-issue with parasitic loss, as they're about the same and relatively insignificant, imo.
Your thoughts?
The I think the electric vs mechanical is a non-issue with parasitic loss, as they're about the same and relatively insignificant, imo.
Your thoughts?
12V x 4A = 48W = 0.06437 HP. Even with losses your still less then a tenth of a horse. You batteries act as an accumlator and so the demand is not the full load.
With a mech. pump you have a lot of other losses. I agree either way the load would not be noticable. I doubt RASP would be more then the A/C compressor and you can not feel it. I don't have exact dyno changes though.
Randy
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