Crankcase Vacuum System

While the design is very complex the operation is very simple to explain.

Crankcase vacuum system. It s an engine performance trick practiced since the late 60s first with passive crankcase evacuation methods or so called pan evac systems. This provides a better piston ring seal less intake charge contamination and reduces oil leaks caused by high crankcase pressures while increasing engine performance. The vacuum part of the pvc system provides the motive power for the flow of clean fresh air through the crankcase and into the inlet manifold via two routes taking with it the various crankcase emissions to be burned up during the combustion process. In an internal combustion engine a crankcase ventilation system removes unwanted gases from the crankcase the system usually consists of a tube a one way valve and a vacuum source such as the intake manifold.

For most modest horsepower street engines however a vacuum pump. The extreme solution to prevent all of this is to install a vacuum pump that continuously draws the pressure out of the crankcase. A properly designed vacuum pump system can deliver like crankcase vacuum to a dry sump. Crankcase pressure is evacuated via the valve cover and pumped to an external tank which vents the pressure and retains excess oil for periodic draining.

Moroso is one of the most popular sources for these solutions. Today manipulating the pan vacuum with a dedicated pump such as those offered by gz motorsports and moroso is more effective and gives the engine builder another tuning tool. Even the length and size of the tubing used in the catch can model for kart racing are critical. This reher morrison big block chevy illustrates the simplicity of an external vacuum pump system.

If you run a dry sump system with a three stage pump one pressure stage two scavenge stages in most cases you cannot achieve a sufficient level 8 hg of crankcase vacuum to achieve that power gain. The unwanted gases called blow by are gases from the combustion chamber which have leaked and pass through the piston rings. Moroso offers a lineup that includes both 3 and 4 vane vacuum. If you can achieve a crankcase vacuum level of at least 8 inches hg you will very likely realize an immediate power gain of at least 15 hp.