Hi Everyone,

I'm new to the Brickboard, we just purchased our 1998 V70R a few weeks ago, but I've got a good deal of experience messing with the boost in my turbo Toyota and I think I may know a couple of ways to solve your problem.

When using a "bleed" type of boost controller you will get much better results if take some steps to optimize how it bleeds air. Right now your controller is having trouble bleeding off enough air to raise boost.

One cause of this can be the orientation of the bleed valve. I'm an artist, not an engineer so I don't know the fluid dynamics, but essentially the air in the source line prefers to continue flowing down the "source" line rather than escaping through a bleed that is perpendicular to the "source" line. If your boost contoller does not force the air in the "source" to flow directly into the "bleed" you can have trouble removing enough pressure to raise boost.

Another cause of this is that there is simply too much air flowing through the "source" line. If there is "X" amount of air flowing through the "source" line but your bleed can only flow "x" amount of air out then you may have trouble bleeding enough air... In this case you can work around the problem by limiting the amount of air flowing through the "source" line. Usually this is done with an inline restrictor of some sort or even just by using smaller diameter hoses.

NOTE: This is "general" boost controller advice. I have NO first hand experience raising the boost on a Volvo and there may be other factors involved that I am not aware of. Use a good boost gauge, listen for detonation and be CONSERVATIVE when you start adding boost.

One more thing... IMO Ball & Spring boost controllers are much easier to install and perform better than "bleed" valves.

- Matt Crawley
1998 V70R awd
1991 Toyota Celica All-Trac