Vacuum is generated in a car engine by the action of the pistons moving up and down, sucking air in during one cycle of the strokes. To give the ideal air fuel mixture the air feeding the engine is restricted therefore a vacuum forms. The vacuum is often made use of by the braking system which uses it to provide power and assist in actuating the breaks.
The vacuum level can be used by a hypermilling driver to improve driving technique. The lowly vacuum gauge is the grand-daddy of fuel economy instrumentation.
Installing and using one remains a cost effective way to help a driver fine tune certain driving tasks for better efficiency, particularly "driving with load" (aka DWL - see the 100+ Hypermiling Tips)
As well as aiding efficiency, adding a vacuum gauge is useful as an indicator of the general health of an engine.
The purpose of a vacuum gauge is to measure how much throttle you are giving and how much load is on the engine. How it helps is by giving you feedback as to how hard you are on the throttle and can therefore ease off a little on the uphills and generally drive with as much vacuum as possible.
General Vacuum information
A normal car engine in good condition will provide vacuum equal to about 17 to 21 inches of mercury , normally expressed as in/Hg.
A vacuum gauge can help identify and diagnose engine problems like mismatched carbs, timing not set correctly, worn rings and valves, air leaks and other items.
Instructions for mod
Please enter your user name and any relevant data in the table
|User Name||Car Make, Model, Year||Cost of Mod||Time to Perform Mod||MPG Before Mod||MPG After Mod||MPG improvement guess||Instruction Link|
|Example Data Saand||Example Data Mazda, 626, 1991||Example Data $5 USD||Example Data 1 Hour||Example Data 27.2||Example Data 29.8||User mod detail or measurement detailed data|
Problems / Consequences of mod
-Faulty installation can result in a unsealed vacuum line resulting in poorer engine performance