[Ron Gusack]

Please help me understanding the whole volume issue. I've always thought this:
Pressure is what determines how much power is required to turn the pump.

Pressure is determined by excess volume and the bypass spring.

If you have a HV pump with the same pressure under the same conditions as a SV pump, the same amount of power will be required to operate the pump. No???

If I put a lower pressure spring in my HV pump, wouldn't I pick up some power??

I just tested my M77HV vs the 22150 Moroso race SV pump. The HV pressure was 70 and quickly dropped to 65, then 60. The Moroso was bouncing between 55 and 50. The HV has the bypass oil returning to the pan and the Moroso doesn't. I'm assuming the bouncing is because of the return differences in the caps. I need to figure out how to drill the cap on the Moroso SV and retest. This was with 10-30 oil at 46 degrees.