Creating a Vacuum in an Engine’s Crankcase

If you are familiar with NASCAR Cup engines, then you are likely aware that they have used their solid-gold R&D budgets to develop drysump oiling systems that use a multi-stage pump to do more than just move motor oil around. The engines are actually sealed tight, and the external oil pump also scavenges air along with oil to effectively pull a vacuum inside the crankcase.

Obviously they are doing that because it helps create horsepower. But the Cup system also comes with a lot of complexity and maintenance, and for hobby-level racers dry-sump oiling systems aren’t usually legal. The good news, however, is there is an option for those of us with cubic zirconia budgets that can get us close to the same result.

As an engine is running, some of the combustion gases will sneak past the rings and create pressure in the crankcase, which is called blow-by. Smart drag racers for years have used vacuum pumps to help gain a few extra