Myth: vacuum vs pressure force?

[2fast4]

For the sake of brainstorming, is the force of vacuum force same amount as pressure force? E.g. if 15hg In vacuum = 15psi pressure?

 

[scottsee]

15hg vac = 7.5psi

2hg=1psi. Thats why when you set base fuel pressure you do it with the vac off. Becasue vac will pull the Pressure down, and everyones is diffrent.

 

[steve]

For the sake of brainstorming, is the force of vacuum force same amount as pressure force?

When reduced to the same units both pressure and vacuum are equal forces.

As Scott was trying to point out pounds per square inch (psi) is not the same unit of measure as inches of mercury (in hg).

I use the online calculator http://www.convert-me.com/en/convert/pressure all the time.

Steve

 

[2fast4]

I'm trying to correlate this to BOV. 1G BOV, on vacuum test it starts to open at 16hg. Someone stated that pressure force and vacuum force is equal. Btw, that explains why it stays open during idle(idle vacuum is at 18hg).

This may not be a valid test method on BOV but seems to be closest to it(being under boost but you can't test it under pressure either).

As I understand it, 1G BOV start to open(under boost) at ~20psi?
I'm not very sure when 1G BOV opens up under boost

 

[steve]

I posted something like this back in 2004.
http://www.dsmtuners.com/forums/showthread.php?t=135492&highlight=BOV+open

The BOV should stay closed under pressure but it doesn't quite work out that way. They all seem to leak at different pressures.