Turbo gauge - how to use??

[WingedWagon]

Okay, y'all, this is a naive post, but this is clubwrx and not i-club, so what the heck, right?

I have the factory turbo gauge on my new '02 wagon. What I want to know is what I'm supposed to be gleaning from it - what's it telling me?? What should I do with the information I'm getting from it? Is it telling me when to stomp the pedal? When to let off? What do the numbers on the factory gauge (-1.0 ... -.5 ... 0 ... .5 ... 1.0 or something like that) mean?

Any help would be much much appreciated. This is my first turbo car. I had another '02 wagon that was flooded & totalled a few weeks ago, but it didn't have a turbo gauge, so I didn't concern myself with it. But now that I have it, I'd really like to know how to make the best of it.

Thanks so much!

--Trace

[ryland]

Basically, when at idle, your engine will have to suck in the air, so you should be getting a negative value. Once you tap the throttle, the needle should jump to 0, or close to it. Once you start to accellerate you should show positive boost. You can use this thread to help you convert the boost shown on the stock gauge to PSI.

Quote from PlatinumWRX in said thread:

"0.1 MPa = 1.0 bar = .987 atmospheres = 14.5 psi = 29.53 inHg"

So basically the boost gauge tells you how much vacuum or boost you have.

More you accellerate, more exhaust gas spins the turbo, more air is compressed into the engine, higher boost readings on gauge.

On a stock car you should see a max of a little below 1.0 bar i believe, around 13.5 psi. You also must have a boost gauge to tune in your MBC if you choose to get one.

[WingedWagon]

Thanks - that helps a little. I think I need to read up on exactly what a turbo does in order to understand the gauge. The engine is less effective when sucking air? So that the turbo force-feeds the engine air so the engine doesn't have to suck? And, now that I know that being in the positive on my gauge means the turbo is boosting, what do I do with that info? Should it affect my driving? Or is it just something we like to see? In other words, should I be driving one way or doing one thing when in the negative on my gauge, and doing another when in the positive?

Anyway, thanks again for the help!

[ryland]

The addition of boost to an engine adds tremendous power. The WRX would be lost without it. Do you notice that your car has more power over 3000 rpm? Thats because the turbo has spooled up to speed at 3000+ rpm and is forcing more air into the engine. More air = more fuel can be burned = more power. A crude analogy could be something like riding a bike. Alone, you have to do all of the work. But if some one runs behind you with their hand on your back pushing you forward, you can go faster etc. That my be a little confusing, but once you understand how a turbo works its all quite simple.

Here is a link that may be able to help you understand how turbos work.

Good Luck!!

[WingedWagon]

Right, I got that. And I know more than it probably sounds like.

But now I understand what the gauge is doing - it's reporting on the compression of the air. What I am wondering is what to do with this information. What does knowing that, at a given time, I'm only spooled up to push 10psi tell me - or that I am fully boosting at 13 or 14 or whatever? I mean, is there a technique to driving a turbo? Do racers (and should I) watch the gauge? Or is it primarily there just to remind me the turbo is working, and to monitor that it is boosting where it should be (or, if I had MBC, if it is boosting where I've set it to boost)?

Thanks!

[WingedWagon]

Oh, and howstuffworks.com rocks. I had already read their turbo section before posting my question! Thanks for the link, though!

[ryland]

Sorry, I guess your question was a little unclear to me. For me at least, when it comes to boost, the more the better. It can also function as a safeguard to alert you that you are overboosting etc. Its a safety precaution just like an EGT gauge.

[kaizenfighter]

Basically you just monitor is to make sure you don't have any leaks or anything wrong. Its not as important til you start adjusting boost. Then you will need to know what levels you are running at all times. For instance. If you floor the car and hit 1.1 mpa, that is about 16 lbs of boost. If you floor is 2 days later and only hit .05 mpa in the same gear and rpm, you'll know you have some sort of leak. Basically is just helps you monitor your car.

[cybertek]

this may be a stupid question but what does egt stand for?i

[kaizenfighter]

I believe exhaust gas temperature. I may be wrong though

[ryland]

Yes, exhaust gas temperature. You need to make sure they dont get too high, the boost gauge can tell you if you are also getting partial throttle full boost problems which can cause problems.