On a turbocharged car the level of boost you run is a direct influence on the amount of power you make. To that end, many enthusiasts have tried all sorts of ways to up the boost pressure. Here is a proven method that is as simple and cheap as it gets yet is also very reliable. Installing a quality boost gauge is something you should do first. Installing an air/fuel gauge, reading your spark plugs, and all other safety recommendations mentioned in Recipe B is a good idea but not absolutely necessary; upping your boost by only 2 psi is within the limits of your computer and should never cause any trouble unless there is some sort of hardware failure (bad fuel pressure regulator or some such occurance).
How does a bleed increase your performance? Easy--it directly determines what level of boost is generated in your intake manifold. Our cars run a vacuum/pressure "feed line" from the intake to the wastegate actuator. If you were to run full boost pressure to the actuator, your boost would always stay low (about 6 psi max) because this pressure would blow open the wastegate and prevent higher boost levels. Your car's stock computer raises the boost above this minimum by "bleeding" some of the air pressure out of this feed line through the opening and closing of the wastegate solenoid; cycling the solenoid reduces the amount of boost pressure in the feed line which then reduces the opening of the wastegate. If you manually bleed more air out of the feed line than the computer does, your boost level will go higher than the computer lets it go. That's all there is to it.
Here's the procedure:
1. Remove the hose coming out of the wastegate actuator can and plug the hose. Find a source of manifold pressure/vacuum (at the turbo's output barb if your turbo has one, or else from the intake manifold itself) and run a new short rubber vacuum line directly from this source of manifold pressure to your wastegate actuator can's barb.
2. Now you have to find the factory restrictor. It's in the wastegate solenoid vacuum lines that you just rendered useless when you unplugged the hose from your turbo OR it might be in a tube that comes straight out of your turbo.
3. Cut your new rubber line in half, then reconnect it using the restrictor.
4. Prepare your bleed valve by closing it all the way and then opening it very slightly. You should just barely be able to blow through it at all.
5. Cut your new rubber line in half again between the restrictor and the wastegate actuator. Get a vacuum line tee and push the two tubing halves you just cut onto the tee. That leaves one barb of the tee open. Mount a check valve to that open barb so that it lets air blow out but won't let air get sucked in. (Make sure you point it the right way!) Now get your bleed valve and, with short rubber tubing, connect it to the open end of the check valve.
Now you dial it in. Take a ride and nail it in a higher gear (so that you can stay in full boost for a little while). Note where the boost levels out. If it isn't quite 2 psi more than stock then pull over, crack it open ever so slightly more and try again. If the boost level is too high then close the valve slightly. Go back and forth until you get it set just where you want it; after that you're done.
NOTE: You can directly control the size of the boost spike with your restrictor: the bigger the restrictor's hole, the smaller the spike; the smaller the restrictor's hole, the bigger the spike. Be careful, though; if your restrictor is too small you may spike all the way to cutout.
Modified 10/3/99.