Boost/Vac Gauge

[ttah8]

So I'm not the most knowledgeable person about the mechanical aspect of cars. But I want to put an A-pillar gauge cluster into my car. I want gauges that have a little more activity to them, not the steady reading kinds like volt meters. I know the A/F gauge is something that I can use. But what about the boost/vacuum gauge? I dont have a turbo or supercharger to monitor the boost, but what about the vacuum? What exactly is the vacuum pressure that it is monitoring, is it some vacuum pressure all normally aspirated engines have, or is it a "boosted" thing.

[Themeneea]

it will read from 20 to 0 PSI of vac.
20 at idle, and 0 at WOT

[Matt95GT]

Right, it only read vacuum, no boost.

Vacuum is actually measured in the unit "InHg." Idle vacuum will depend on the engine, but will often hit mid 20's. (29.9 InHg is complete vacuum... won't ever go that high) Full throttle will go up 0. The vacuum gauge activity will roughly follow throttle activity.

Alternatively, you can purchase a vacuum only gauge that won't include the boost side and therefore feature a bigger sweep. I'd do that instead. Boost gauge on a non-boosted vehicle will get laughed at.

[ChevelleSSLS6]

/\very true, I've laughed at many people before.

[TA^Guy]

I'm sorry but I maybe the only one that finds this as a waste or time and energy?

A/F are a waste not to mention a gauges that you don't even know what to do with it.

I don't know I installed our gauges to montior how the car is running and be able to preduct a problem before I have one.

I say if you want something distracting you in your line of sight while you drive get a bobble head.

On a postive note to this reply. The A/F gauges and Vacume gauges should keep you well entertained.

[Matt95GT]

^I agree with John, A/F and vac are actually completely useless... especially since this is the performance section of the forum. Those 2 gauges can be considered "appearance" only.

The bobble head would certainly be entertaining, but oil pressure and voltage would be much more useful.

[Themeneea]

Originally posted by Matt95GT
^I agree with John, A/F and vac are actually completely useless... especially since this is the performance section of the forum. Those 2 gauges can be considered "appearance" only.

The bobble head would certainly be entertaining, but oil pressure and voltage would be much more useful.

but if he gets a vac leak, he would know from the vac gauge

[Matt95GT]

Originally posted by Themeneea
but if he gets a vac leak, he would know from the vac gauge

Good point, although my feeling is the more you complicate the vacuum line distribution, the more chances of having a leak. *sigh* Part of my inconsistent fuel pressure woes.

[DontPassTheFence]

with my new scan guage -- i have seen that my LD9 has roughly 16-19 in the vac/boost parameter, ive never watched it at wot though...

anyways, to stay on topic here, id say go for oil pressure and voltage as mentioned above, oil pressure its always good to know, that way your know your car has a problem before you hear the aftermath of having no oil pressure (ive been down that road before... destroyed a 2.8L engine that way.)

[ChevelleSSLS6]

Vaccum gauge is good for diagnosing engine troubles and learning how to drive for maximum efficency (which is good), but oil and volts, as the other guys have said already, should be priority one.

[ttah8]

I have decided to go with vac and volts. Volts will be useful since I'm running a sub. I figure thats a good mix, one gauge for functionality and one for looks. So the vac gauge will fluctuate I get on and off the gas?

[Themeneea]

^yes

[DontPassTheFence]

unless you have a vac leak.