What Are Dry Sump Systems?

The Facts

• Wet sump systems -- the standard oiling systems on street cars -- work by sucking from the standard oil pan into the stock oil pump, which supplies oil to the engine as needed. In racing conditions, the vehicle's momentum causes the oil to collect around the sides of the pan, away from the stock oil pump's intake valve. As such a loss of oil pressure can reduce the vehicle's horsepower and oil aeration, a new sump system was necessary for racing conditions.
  
  

How They Work

• Dry sump systems use a separate, large reservoir to store the vehicle's oil, with an outlet at the bottom for a constant oil supply to the engine. The oil pump typically consists of two to six separate sections, the first of which contains an adjustable pressure regulator to deliver oil to the engine under pressure. The other stages return oil from the dry sump pan back into the top of the oil reservoir, sometimes through an oil cooler.
  
  

Advantages

• The dry sump system increases engine reliability through its supply of a uniform level of oil pressure, even in racing conditions. The use of a shallower oil pan allows for a lower placement of the engine in the vehicle's chassis, and the ability to mount the oil tank remotely in the vehicle allows for greater capacity. This system allows for adjustable oil pressure, and improves horsepower due to decreased viscous drag. Oil coolers can easily be installed between the returning stages and the oil reservoir.
  
  

Sections

• One way in which dry sump system models vary from one another is in the number of pressure and scavenge sections. Dry sump systems with two to four of these sections typically have one pressure section delivering oil to the engine, with the rest devoted to scavenging oil and returning it to the top of the reservoir. Dry sump systems with five to six sections usually add a second pressure section. Six usually ranks as the limit to the number of sections on a dry sump system.