Boost Gauge Questions
 

I just had the AutoMeter Lunar gauge cluster installed, along with a boost and fuel pressure pillar gauges. Question I have concerns the Boost gauge. What exactly does the vacuum side of the gauge mean? When I'm just motoring around town under moderate throttle, it ranges from 10 to 5 or so. When I hammer it in 1st or second gear I might see 0, maybe 1 or 2 on the Pressure. It seems I really only get into the Pressure side of the gauge when I really hammer it in 3rd gear and I'm really at high speed I'm registering up to 8 psi at this point, which is what I expected. And it is a very gradual build up to the 8 pounds. Can someone explain the progression from the VAC side of the gauge through to the Pressure side of gauge? Thanks!

Vacuum is when your throttle blade is mostly closed, the outside air can't get in and the engine is still spinning, trying to suck it in, so it forms a vacuum. Once you stomp on the gas the throttle blade opens, air rushes in and fills the vacuum, and your manifold will be close to ambient air pressure (the 0 marker). Once the blower starts to work, up goes the boost.

this is normal with a vortech style blower they dont make boost till high Rpm .

Vacum is the motor trying to suck air in boost is the blower forcing air in.

jonnyk explained it better than i could.

Thanks guys! Very helpful.