The Completely Unofficial Boost Machine FAQ

brought to you by Christopher Plaskett (AxeYrCat)

Before you even consider this mod, purchase and install a boost gauge. Don’t have one? Come back when you do. Have one already? Great: Let’s do this.

First of all, read the AutoSpeed articles: part 1 and part 2.

Also, remember that Steve Schwing’s fotki album is an incredible resource. Reference it often. There are pictures and explanations in abundance, and they will make your life considerably easier.

What is the Boost Machine?

The Boost Machine is essentially a manual boost controller.

Why do I want one?

So you can adjust your boost levels. More boost = more fun.

Why not just use a different N75 valve?

Because they tend to cause boost spikes, and those spikes can be enough to send your car into limp mode if it thinks it’s over-boosting. Furthermore, they’re just plain irritating when you’re driving. Retaining the stock N75 valve keeps power delivery smooth but provides more boost.

What about the cheaper manual boost controllers?

They’re exactly that – cheaper. The Boost Machine uses valves that are considerably more sophisticated than a screw-type manual boost controller, and it allows for much more accurate tunability.

How does the Boost Machine work?

Haven’t you been paying attention? If you’re not going to read the suggested material, don’t bother coming to class! Now read the AutoSpeed articles: part 1 and part 2.

Where do I get the parts to make a Boost Machine?

Contact Metal Work Pneumatic to find a local distributor, and order the FRL family BIT 1/4 0-30 PSI valve. The relief valve (optional) and the one-way valve can be had through Norgren, and the part numbers are VO7-200-NNAA and T55A2800, respectively. The site isn’t the easiest thing in the world to navigate, but you’ll notice on the front page that there’s a link that reads “If you know your part number, click here.” Take advantage of that. You’ll also need some brass piping which should be available at a local hardware store. Note that you will want two dual-sided brass barbs so that you can easily plug into the hoses that were originally connected to the N75 valve. Remember to buy some Teflon tape for the threads of your piping. You’ll also need some silicone hose which can be had from Hose Techniques. Don’t forget to pick up some small hose clamps or some zip ties as well.

Now that I have all the parts, what do I do with them?

This should be pretty obvious, but you assemble them! Pay attention to the arrows on the valves as proper orientation is key. The one-way valve lacks arrows, but the collar should be closest to the center. Forgive the basic diagram:

How do I install it?

Remove the air hose going into the bottom of the N75 valve and plug it into the ‘IN’ side of your Boost Machine (where the red arrow is in the diagram). Now connect the ‘OUT’ side of your Boost Machine (where the green arrow is) to the bottom of the N75 valve. Voila!

How do I adjust the boost?

And just when I thought you had been paying attention! Remember those AutoSpeed articles that I told you to read (twice)? They describe how to adjust the Boost Machine. However, since if you haven’t read them at this point, you probably aren’t going to, I’ll throw you a bone. The second valve adjusts boost and the first adjusts creep. By loosening the second valve (re. turning it counter-clockwise), you are adding boost. Start with the valve all the way closed (turned clockwise all the way), and then open it up about three revolutions. This probably will not effect your boost levels, but it will get you closer than starting at full-open. From there, turn it up at set increments (half a turn or a full turn) until you start to see change. IMPORTANT: You can turn up the boost more than your computer would like you to, and thus, throw an over-boost code! If you do not have a VAG-COM tool, err on the conservative side to avoid limp mode!

How do I adjust boost creep?

The relief valve controls boost creep, but since the 1.8t doesn’t have a particular problem there, you can choose not to use it at all and instead just run a straight pipe. However, my experiences running without the relief valve but with the regulator valve have taught me that if I’m on boost hard and then slowly back my foot off of the gas pedal, it feels like hitting a wall when boost drops out. This can be smoothed out with the relief valve. After you have your boost set as you want it, it’s time to adjust the relief valve. Completely opposite of the second valve – the regulator valve – the first valve – the relief valve – is open when it’s turned fully counter-clockwise. Start there, and then turn it about ¾ turn clockwise. This should get you pretty close to where you need to be. Make any further adjustments as you see fit, but realize that a little goes a long way with this valve.

What if I throw an over-boost code?

Use the VAG-COM tool that you were supposed to have access to before you started playing with your boost.

Are we done here?

With any luck, yes. You should have a fully working boost machine at this point. If not, you probably did something stupid or failed to read the directions. Check your work before you post something on the forum – embarrassing yourself in a public place is never fun. Enjoy!