On a turbocharged vehicle, the turbo compressor's job is to pressurize the air from the car's intake and then force-feed it into the engine. This pressurized air is normally ingested into the engine and burned with fuel to make power. However, when you take your foot off the gas and the throttle body closes, a pressure spike occurs from the built up air in the charge piping. This pressure spike must be vented or the turbo will be damaged from compressor surge.

There are 2 devices available to relieve these pressure spikes - CBVs (Compressor Bypass Valves) and BOVs (Blow Off Valves).

CBVs and BOVs work slightly different from one another, but essentially do the same thing.

A CBV (located on the turbo itself) takes pressurized air and releases it back into the compressor air inlet. A BOV can be located anywhere along the turbo piping before or after the intercooler, and can either be open or closed. An open BOV releases the pressurized air into the atmosphere making the well-known "psssh" sound. A closed (or recircluated) BOV releases the pressurized air back into the compressor inlet piping similar to a CBV.

Volvo turbos have a CBV located right on the turbo assembly, and they generally work perfectly fine. However, you may want to replace the stock CBV for a few reasons:

• Some people love the "psssh" sound of BOVs venting to atmosphere, so they feel compelled to put one on.
• As the CBV ages, the rubber diaphragm inside tears causing boost leaks and a loss of power. A BOV is an alternative to replacing the CBV.

If your CBV is torn and leaking you can either repair it with one of our CBV Upgrade Kits or consider removing the CBV altogether and installing a blanking plate in its place (once a blow off valve (BOV) has been fitted to the car).

Why not simply disconnect the CBV to keep it closed? While this is often recommended as easy method to "disable" the CBV, it has been shown that a disconnected CBV actually still leaks some air, and many have boost issues with both a BOV and a disconnected CBV. The best solution is to remove the CBV altogether and install a blanking plate in its place.

QBM's blanking plates are manufactured from the highest quality aircraft aluminum, providing a perfect fit and finish.

Warning: Do not install a blanking plate unless you are installing a BOV! You must vent the pressurized air via a CBV or a BOV. If you do not have a BOV and remove the stock CBV to install a blanking plate, you risk damaging the turbocharger.

Fits all Mitsubishi TD04 family turbochargers (09B/12T/13G/14T/15G/16T/18T/19T/etc).

CBV Blanking Plate: $19