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.