The most common reference to a sump system is made when referring to the oil circulating system of an engine. There are two main types of sump systems, wet systems and dry systems. While both systems serve the same basic purpose to rid the sump pit of liquid, each system uses different parts and has its advantages and disadvantages.
A wet sump system and a dry sump system perform the same basic function in the oil circulating system, to rid the sump pit of oil. Each system pulls the oil up from the sump pit, the oil pan in this case, and circulates it to another location. The main difference in the function of a wet and dry sump system is that the wet sump system pulls the oil directly back into the cars engine while the dry sump system sucks the oil into a separate reservoir before its recirculation into the engine. The sump, or oil pan, is left "dry," hence its name.
One of the main differences between wet and dry sump systems are the parts needed to form the system. The wet sump system is very simple and requires only five basic parts, an oil pump, the main bearing cap, a windage tray to control oil splash, an oil pump pickup, and the oil pan. Contrarily, a dry sump system is incredibly complicated and requires many more parts. The main parts required for a dry sump system are a breather tank for overflow, external oil tank, oil preheater, dry sump oil pan and pump, scavenge manifold, racing oil filter, in-line filters, and various mounts and filtered fittings. In addition to the need for extra parts, a dry sump system requires special parts specific to the dry sump system such as the oil pan, oil pump, and external oil tank.
Strengths and Weaknesses
Both wet and dry sump systems have distinct strengths and weaknesses. The wet sump system is ideal for passenger cars and light racing due to its low cost, ease of modification, light weight, and simplicity. However, the wet sump pump is also bulky and inefficiently uses oil at high speeds with rapid directional changes. The dry sump system is ideal for race cars due to its increased power from less weight present in the oil pan, reduction in windage, and improved ring seal. The dry sump system also allows the advantages of increased oil capacity because of its external tank, adjustable oil pressure, and lower engine placement due to the shallower oil pan needed. Despite all of its advantages, the dry sump system is also incredibly costly and complex, making it an inefficient option for mainstream oil circulation systems.