Everything you need to know about Boost Gauges

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Random Dude
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Everything you need to know about Boost Gauges

Postby Random Dude » Sat Nov 24, 2007 2:10 am

Refers to these two threads:


MrEs wrote:Sounds perfect to me mate Wink

And to continue on with the discussion of mechanical/electronic differences in the original thread (viewtopic.php?p=432975).

Reason I got an electronic boost gauge:

a) Generally a neater install in the engine bay as you can bend/tie-down electrical wires more easily then vacuum house. And you don't have the hassle of running the hose through the firewall and what not.
b) You can set peak warning signals so it warns you if it over-boosts.
c) Record peak boost, so if you have a hard day of driving like at a motorkhana or something you can check if your car over-boosted during the day. And if it did FIX IT Razz
d) I can record a few mins of driving in my boost gauge and then play it back which is useless but way cool LOL!

E) And most importantly electrical will always be more accurate. (And more expensive when compared to a similar quality mechanical one)

The basic theory is this.

A mechanical uses pressurised air (boost) carried in a tube to the back of the gauge. This boost presses on a diaphragm and is then converted into a current which moves the indicator. Yes these can be sometimes quite inaccurate. Depends on how much you pay of course. This will require the tube to be fed through the firewall and travel over a meter before it gets read rather then a few CMs an electronic set up has to travel before it gets read.

The electrical ones use a transducer which is again a type of diaphragm that converts the pressure signal into a current. These are far more accurate because they consist of solid state technology. The transducer is usually located at the point of reading or near by and then only electric wires are fed back to the gauge display itself.

Also the electronic boost sensors are usually peizo-electric. A crystal that generates a voltage proportional to the pressure. piezo sensors do not need re-cal like a spring sensor would and can’t go off like a spring/contact/normal diaphragm sensor can.

Startrippa wrote:
fulvio wrote:Hmmph, this is just wonderful.

Just before passing 10 PSI the gauge makes a buzzing sound for half a second. This happens all the time and whether it's hot or cold outside/inside, etc.

Have checked all wiring and vacuum line and there are no vibrations or hiccups that I can see anywhere.

This sucks :x

hehehe na, every Apexi EL2 Mech I've seen has done that, Styla's did it, My one did it and another club members one I heard did it so its just normal for the mech gauges :)

Stress less, Just crank up the radio and you can't hear it :D

Startrippa wrote:
fulvio wrote:So.. I finally hooked up my mechanical Apexi Boost Gauge today. Just wondering what the readings are supposed to be.

Used the following DIY by MrEs:
viewtopic.p ... highlight=

I have a MY03 completely stock apart from an Apexi CAI (inside the engine bay) filter.


1. Idles at around 19 IN HG
2. The dial doesn't go past 14 PSI


Nah, the 03 WRX has about 14psi and the -psi you get at idel is a vacume reading coz the turbo isn't forcing the air in

Random Dude wrote:I found the GD install guide for a boost gauge (nice work Denis) but couldn't find anything for the GC8 (MY00) model.

I need somewhere to hook up the boost guage power. I have sussed out two points, either off one of the harnesses going into the instrument cluster, or somewhere near the fuse box.

The ground I can handle, but does anyone know which one I can use for the Illumination (ie, when the parkers or headlights are on)

PAT555 wrote:Pull out the head unit and run power and illumination off that loom.

Lupin wrote:Or not even pull out the head unit, get it from the Cig lighter.

If you want to get it from that area, parker wire can be found on the back of the fog light switch.

00WReX wrote:Hey Brenton,

I just tapped in to the front fog light switch...nice and easy to get to.

I just quickly put this together, it may assist - GC8 WRX :thumbs:


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