When does a Vacuum Pump benefit an engine?
A vacuum pump, in general, is an added benefit to any engine that is high performance enough to create a significant amount of blow-by. A vacuum pump will, in general, add some horse power, increase engine life, keep oil cleaner for longer.
How do Vacuum Pumps work?
A vacuum pump has the inlet hooked up to one or both valve covers, sometimes the valley pan. It SUCKS the air from the engine, thus reducing the air pressure build up created by blow due to combustion gases going past the piston rings into the pan. Vacuum pumps vary in the amount of air volume (CFM) they can suck so the potential VACUUM a pump can create is LIMITED by the amount of air it can flow (CFM). The exhaust from the vacuum pump is sent to a BREATHER tank with a filter on the top, which is intended to retain any fluids (moisture, unspent fuel, air born oil) sucked from the engine. Exhaust air goes to the atmosphere thru the air filter.
Vacuum Pump Sizing
Vacuum pumps can be rated by their ability to flow air, the more air a vacuum pump flows the more vacuum it will make on a given engine. A “small” vacuum pump would indicate a less airflow capacity than a “big” vacuum pump. Airflow is measured in CFM (cubic feet per minute), vacuum is measured in “inches of Mercury”
All engines create a certain amount of blow by (leakage of compressed fuel and air past the rings into the pan area). This blow by airflow creates a positive pressure in the crankcase, the vacuum pump “sucks” air out of the crankcase with its negative airflow. The net difference between the air being sucked out by the pump and the air generated by the engine with blow by yields the effective vacuum. If the pump is not sized, plumbed and geared correctly, it may not be able to move enough air to create a negative pressure in the crankcase.
Post time: Jun-21-2021