Certain experiences scar you for life. I have yet to get over the trauma of the demise of my Dodge Colt turbo. I sold my Colt turbo to a buddy because he was in dire need of a vehicle. I didn't want to sell the vehicle but due to his situation I felt he needed it more than I did. He drove the Colt for about 30,000 miles before it blew up on his way home from a trip to Mexico. When I asked him what happened, he said the car ran out of oil. He would later confess that he hadn't changed the oil since I sold him the vehicle. Yes, he ran the car for 30,000 miles without changing the oil, not once. He also had the audacity to mention to me that it was the most reliable car he had ever owned before it blew up. Now you feel my pain. On top of all that he never even paid me for the car! Having shared with you my oil-related trauma, it must be learned that the engine's oil supply is its livelihood. A poorly lubricated engine will result in abnormal wear and possibly engine failure.
Wet Versus Dry Sump OilingIt is important to have an oiling system that is up to the task at hand. Would you take a pea shooter into battle? We'd much rather take the grenade launcher. The same goes for an engine's oil system. The factory oiling system probably will work fine on a mildly tuned engine but when you take that same engine and generate five, six or even seven times the factory output then you better make sure the engine is well lubricated at all rpms.
There are two types of oiling systems, "wet" and "dry" sump systems. A wet sump is found in 99.5 percent of the vehicles on the road today. A "wet" system refers to the oil that is stored in the bottom of the oil pan. The oil is distributed throughout the engine through an internally mounted pump. An oil pickup is mounted to the oil pump and pulls oil from the bottom of the oil pan. However, there are aftermarket "wet" sump systems that utilize an externally mounted oil pump to distribute the flow of oil throughout the engine.
On a "dry" sump setup the oil is stored in a separate tank leaving the oil pan basically dry. Instead of having an internally mounted oil pump like in a wet system, on a dry setup the pump is mounted externally with multiple stages used for removing the oil from the pan and to route the oil into the separate storage tank. For example, on a three-stage pump setup two of the stages are used to remove the oil from the pan and pump it into the storage tank while the final stage is used to pump the oil from the tank to the engine for lubrication.
The main advantage of a dry sump system is the ability for the engine to generate more horsepower. Since there is very little oil in the pan the oil is not getting sloshed around when the car is moving. On a wet sump system the crankshaft and the oil essentially share the same space and the oil oftentimes gets splashed onto the crankshaft. The excess oil on the crankshaft requires horsepower to turn and in doing so you lose horsepower. As we mentioned, on a dry setup the oil is stored in an external tank so there is no oil to splash onto the crankshaft.
Besides getting better oil control with a dry sump system there is another key benefit of having this type of system; the ability to pull a partial vacuum from the crankcase. For example, on Honda B-series engines the vacuum is pulled from the PCV (Positive Crankcase Ventilation) valve that is usually mounted on the backside of the block. The PCV valve is connected to the intake plenum and its job is to relieve crankcase pressure. The positive pressure in the crankcase would counteract with the motion of the piston going up and down. If there is positive pressure in the crankcase the piston would have to work against those forces.
Removing crankcase pressure is even more crucial on high-compression and forced-induction engines. Any time cylinder pressure is increased via compression or forced induction, some of the pressure is going to get by the rings, which is known as "blow-by".No combustion chamber is 100 percent sealed from the piston rings. Most typical engines will see about two to four percent static leakage. When an engine is running the percentage of leakage increases. When you consider an engine that generates 30 to 40 psi of boost pressure it is essential to remove the excess crankcase pressure.
We spoke to Dave Hsu from Skunk2 regarding to the company's two race cars which both utilize a five-stage dry sump system on the K-series engine. Hsu felt that the increased output of the engine from the dry sump system is due to a combination of both the decreased "windage" effect (weight of the excess oil) and the crankcase vacuum being pulled from the engine.
The obvious drawback of a dry sump system is its price tag. A full dry sump system can run in the neighborhood of $1,500 to 2,000. However, if you consider the options of either spending $1,500 or losing a $3,000 to $6,000 engine the dry sump is a bargain. With the popularity of the B-series engines Moroso even makes a complete dry sump bolt-on kit. The company has tested their system on the dyno and has seen gains as high as seven to eight horsepower to the wheels. When every bit of horsepower counts at the track, seven horsepower can be the difference between winning and losing.
While there are merits to both the wet and dry oil sump systems, the dry system may be the way to go when performance is your main objective. Consider it an insurance policy for your engine.