Orbital Rating in ml/rev.(c.i./rev.) 100 (6.1) 125 (7.6) 160 (9.8) 6-inch Ram 2.7 2.2 1.7 8-inch Ram 3.6 2.9 2.3 10-inch Ram 4.5 3.6 2.8 The pump has an all steel housing and puts out 4.5 GPM of flow and 1650 PSI of pressure Stock TC Pump Flow Rate 2.4-2.8 @ 1350-1450 Calcs indicate: (seems: idle no load pressure is 80-125 psi) Pressure is needed to actually turn the tires. Flow is needed to maintain desired turning speeds. Sock pump has sufficent flow for the smaller size ram and orbital @ 3 turns lock/lock pressure might not be high enough depeding on loads. Either high idle switch or smaller pully will help with that.