Justin@VMP
May 14th, 2006, 11:14 PM
I got sick of the problems with my Greddy Profec B, so I decided to make my own boost controller.
I went with a brass adjustable pressure relief valve from www.McMaster.com (http://www.McMaster.com), go to the site and search for PN 48935K25, it runs $7.70.
http://www.mcmaster.com/catalog/112/gfx/large/48935kp1l.gif
There is a ball and spring inside, the knob on top can be adjusted to raise boost, up to 20psi with the supplied spring.
If you run more than 20psi you'll need to install a stiffer spring inside.
The bottom is 1/4" NPT, you can get a 1/4" NPT female X 1/4" brass nipple from McMaster or the hardware store, such as PN 5346K42 or 91465K951. For the top connection I took a piece of 1/2" heater hose and clamped it onto the adjuster knob, this worked out well on my car because there was a 1/2" fitting on the upper intake manifold (for the PCV system).
You'll want to install the ball in the top part of the valve, and the spring below it (this is the way it comes). This way the boost from the intake manifold pushes on the ball. Its imperative that you drill a 1/16" bleed hole between the ball and turbo wastegates, otherwise the boost controller won't work right. Under vacuum the ball will seal and prevent this from becoming a vacuum leak.
http://www.vmptuning.com/pics/BoostController.jpg
You could easily turn this into a dual stage boost controller by adding a solenoid to bypass the boost controller and just run off the wastegate spring.
I went with a brass adjustable pressure relief valve from www.McMaster.com (http://www.McMaster.com), go to the site and search for PN 48935K25, it runs $7.70.
http://www.mcmaster.com/catalog/112/gfx/large/48935kp1l.gif
There is a ball and spring inside, the knob on top can be adjusted to raise boost, up to 20psi with the supplied spring.
If you run more than 20psi you'll need to install a stiffer spring inside.
The bottom is 1/4" NPT, you can get a 1/4" NPT female X 1/4" brass nipple from McMaster or the hardware store, such as PN 5346K42 or 91465K951. For the top connection I took a piece of 1/2" heater hose and clamped it onto the adjuster knob, this worked out well on my car because there was a 1/2" fitting on the upper intake manifold (for the PCV system).
You'll want to install the ball in the top part of the valve, and the spring below it (this is the way it comes). This way the boost from the intake manifold pushes on the ball. Its imperative that you drill a 1/16" bleed hole between the ball and turbo wastegates, otherwise the boost controller won't work right. Under vacuum the ball will seal and prevent this from becoming a vacuum leak.
http://www.vmptuning.com/pics/BoostController.jpg
You could easily turn this into a dual stage boost controller by adding a solenoid to bypass the boost controller and just run off the wastegate spring.