depends on where you are reading pressures-----in an engine with sealed crankcase and drysump or possibly just a vacume pump, the oil pressude normally seen on the guage will be result of differential pressure/vacume of oil pump and crankcase vacume------


One of the recent 1400hp 500cid we ran with 5 stage pump had so much vacume from the scavage side that positive pressure reading could/would go toward zero and turn on a 5 psi low pressure warning lite !!!!!!!!!!!


There was enough suction that I actually believe that we didn't even need the positive pump stage---coulda let the scavage pull the oil thru----------