Does engine vacuum reach a certain level or become a "full vacuum" to the point where there really isnt any such thing as the need for more? I don't know enough about the physics or measurement of vacuum but I thought to increase the vacuum the booster sees to improve braking but I am thinking that the vacuum in the booster basically gets to a full vacuum and thats it, its up to how large the diaphragm's surface area is to change braking pressure. Am I right in this or is there room to increase vacuum seen by the booster with an auxiliary pump?

 

Anyone?

 

From what I have gathered, engine vacuum should be anywhere from 8-22inHg. So the most vacuum the booster ever sees is about 18-22inHg, higher at idle than cruising but even higher when on decel at higher rpms with the throttle closed. A "full" vacuum would be a vacuum as strong as atmospheric pressure (atmospheric pressure is what acts on the pedal side of the booster against the vacuum assisted side). Atmospheric pressure is approx. 14.7psi @ sea level or 29.9inHg. No engine is going to make that much vacuum at least at idle. 22inHg equals about 10.8psi. So I guess its worth running an electric vacuum pump designed to create a 20-22inHg vacuum at all times to ensure the booster is working as best it can. Let me know your thoughts.