Dry Sump - Advantages

Advantages

A dry sump offers many advantages, the most obvious of which are increased oil capacity afforded by the remote reservoir and the capability to mount the engine lower in the car because of the thinner profile of the sump thereby lowering the overall center of gravity. The external reservoir can also be relocated to another part of the car to improve weight distribution. Increased oil capacity by using a larger external reservoir than would be practical in a wet sump system allows the oil to cool and release entrained gasses from ring blow by and the action of the crankshaft. Furthermore, dry sump designs are not susceptible to the oil movement problems that wet sump systems can suffer due to high cornering forces. If the oil in a wet sump is forced to one side in the oil pan the oil pump pickup tube can be temporarily uncovered leading to a loss of oil pressure. Because the scavenge pumps are typically mounted at the lowest point on the engine the oil flows into the pump suction by gravity rather than having to be lifted up into the suction of the pump like a wet sump does. Also the scavenge pumps can be of a different design that is more tolerant of entrained gasses than the typical pressure pump which can lose suction if too much air is mixed into the oil. Since the pressure pump is typically lower than the external oil tank it always has a positive pressure on its suction regardless of cornering forces. Another phenomenon that occurs in high-performance car engines is oil frothing up inside the crank-case due to the very high revs agitating the oil. Lastly, having the pumps external to the engine allows them to be maintained or replaced more easily.

Dry sumps are common on larger diesel engines such as those used for ship propulsion. Many racing cars, high performance sports cars, and aerobatic aircraft also utilize dry-sump equipped engines because they prevent oil-starvation at high g loads, and because their lower center of gravity positively affects performance.