The three-stage dry sump pump has one pressure section and two scavenge sections, while the four-stage pump has one pressure and three scavenge sections. The pressure section of each feeds oil to the block, while the scavenge sections pull oil from special pickups in the dry sump oil pan. The four-stage dry sump pump is plumbed like the three-stage, but the line from the additional scavenge section can be routed to pull excess oil from the lifter valley. This keeps oil from sloshing around in the top of the engine and running down onto the rotating assembly, reducing windage and increasing horsepower. Moroso's five-stage pump, with four scavenge stages, is capable of creating the higher crankcase vacuum needed by today's large displacement drag race engines. A Moroso innovation, the "4-1/2" Stage Pump, is engineered specifically for NHRA Pro Stock engines. Unlike a standard 5 stage with 1.100" scavenge sections, the "4-1/2" Stage Pump features 1.375" sections of which the 3 front sections are bypassed on the inlet side creating increased vacuum while still scavenging the maximum amount of oil out of the pan.

"4-1/2" Stage For NHRA Pro Stock applications Three 1.375" scavenge stages are fed internally from both sides using four inlets and four outlets New scavenge design pumps 20% more per stage than our standard 4-Stage pump and 30% more than gear pumps Capable of creating over 20" of vacuum in well sealed engines .750" pressure stage sized perfectly for Pro Stock engines for less oil bypass and more horsepower Custom applications also available

Five Stage For large displacement "mountain motors" Four 1.100" scavenge stages produce higher crankcase vacuum to improve ring seal and reduce pan volume. The result is less windage and more power!