Two main types of oil storage and delivery systems exist for an internal combustion engine -- a wet sump and a dry sump. Most vehicles use a wet sump system, which means all oil is located and stored in an oil pan. A dry sump stores the oil in a separate tank. High end racing and horsepower applications tend to use dry sump systems.
In a wet sump system, some of the engine oil is in contact with the crankshaft, causing resistance and slowing down the rotation of the engine in a process known as "windage." With the oil stored elsewhere and pumped to the engine as needed, which is how a dry sump system works, there is only enough oil to keep the engine properly lubricated. Excess oil is not working against the operation of the engine. This helps the car achieve top speeds and get the highest possible horsepower the engine is capable of producing.
More Oil Capacity
The oil capacity of a dry sump system is not limited by the size of the oil pan. This means more oil can be used, which helps the engine stay cooler. Temperatures are kept lower because the oil is not as hot when it is pumped back to the engine. The lubrication is more effective because the engine oil is not broken down as rapidly by heat and wear since there is more of it available.
Steady Oil Pressure
In a wet sump system, the oil pressure varies because the oil pump is running off of the engine's rotation. When the engine is moving faster, more oil is being pumped, with less being pumped at slower speeds. A dry sump system has consistent oil pressure at any speed, and the oil pressure can be changed as necessary through the external oil pump. This helps all components stay properly lubricated under any conditions.
Greater Engine Flexibility
Dry sumps use a shallower oil pan, which means less space is taken up by the oil pan. This means the engine can be moved lower into the chassis of the vehicle, which makes it easier to access for assembly and service.