In theory the load on the electric pump would be greater due to energy loss in conversion. Either would be totally insignificant.

 

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.

 

My thoughts lol? Get on Jeg's, spend $85 on a 7psi pusher, another $35 on replacing all your banjos with some nice anodized 6an fittings and a relay, wire that relay off your stocker LP, and forget about you LP/low pressure problems. If you have $600 burning a hole in your pocket then by all means, blow it

 

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