Ok I just bought a new pully for my blower. Its a 2.75 inch one should be good for over 12psi on my motor.

I dont have a nice interior boost gauge I'd like to have. I bought a cheap $20 Actron Vacuum gauge that also shows Fuel pump pressure in psi for positive pressure. It goes to 10 psi. I thought a pound per square inch is a pound per square inch. But it only went up to 4 psi at max rpm. I now its putting out WAY more than that because the hose piece that connects the ducting with the throttle body not only bulges out when I snap the throttle like it used to with the 3.05 inch pully, it looks like its going to freaking explode.

I took the gauge and blew on it as HARD as I could and could only get it to go to 2 psi.

Is it differant because liquids dont compresses and gases do?

Help me out here.

 

Air gauges and liquid gauges are not interchangeable.

 

Why though? Im the type that not likes to know what it is, but likes to know why it is.

I mean isnt a pound per square inch of pressure a pound of square inch of pressure whether its force is exerted by a liquid or a solid?

Its like a ton of feathers or a ton of bricks. There both a ton no matter what makes it up.

And this gauge is for air on the vacuum side and liquid on the pressure side.

 

Make sure that the gauge that you have is reading in "In.Hg" for vacuum and "PSI" for boost.

the positive scale might be different, Example: "In.H2O" or something.

just a thought
later
larry

 

No its in psi I'm sure of that.

Anyone else?

 

I think you summed it up when you stated cheap $20 gage. Go get a VDO 0-15 or 0-30 psi boost gage.

 

The boost guages from autometer can be used for engine vaccume or positive boost from a blower. In vaccume, it measures In. of HG, In boost, it measures PSI. its all included in the same guage, and the needle starts in the middle of the left, goes up for boost, down for vaccume.

 

You got the concept right, PSI is PSI. I would fault the gauge. Test it againts a good gauge.

People are good suckers and lousy blowers

You can suck 20" Hg, but only blow 2 psi.

 

wow 20" HG? i could only register 6" on my boost guage. You must be a really good sucker!