okay, on our boost guages. from zero to the right is boost in PSI. we all know what that is. but to the left. HG, what the hell is that.

also, when i see people talking about modding. there is always talk of some option B. what the hell is that too?

 

u made a post on this lastnight and I answered it for u... what happened ?

 

it told me it didnt post, there was a server overload or something. i couldnt find it after that and its not in "my posts." i apologize for double posting

 

That is Vacuum on the left side of the gauge..

Why Use a Vacuum or Vacuum/Boost Gauge?
Vacuum/Boost gauges are used on non diesel, turbocharged or supercharged vehicles and monitor the boost level. The gauges are used to tune waste gates or for pulley sizing (on supercharged) and monitor the manifold boost level. The vacuum portion of the gauge measures manifold vacuum.

Vacuum/Boost gauges are valuable with nitrous oxide systems to indicate detonation and for indication of leaks, worn parts, and malfunctions. Often used as an engine analyzer and tune-up gauge, the gauge indicates if air is being drawn into the systems from anywhere other than the carburetor which adversely affects the air/fuel mixture.

When used for manifold vacuum, during normal driving the gauge will indicate vacuum. As you accelerate, the vacuum level with decrease. When used to monitor crank case vacuum in nitrous applications a vacuum gauge can be an excellent indicator of detonation. When detonation occurs, vacuum declines.


and the option B is a Kit that comes with parts needed to install a surge tank for dual pass side covers.

this is basically a cooling mod.