How Dump Valve Works

How do these car parts help to relieve the strain in an engine?

A dump valve is designed to release unwanted pressure in a turbocharged car engine -pressure that, if left unchecked, would quickly cause great damage. The valve itself resembles a metallic tubular drum and can usually be found between the intercooler and the air inlet hose to a turbocharger.

How the system works depends on the kind of dump valve, but both types seek to negate the effect of compressor surge, a process where the action of the throttle plate closing on a turbocharged engine causes the high-pressure air within the intake system to be blocked and also forced back into the compressor. The first type of valve, known as a compressor bypass valve (CBV), is an engine manifold, vacuum-driven device that releases unwanted pressure in the engine’s intake system before rerouting it via a hose back to the non-pressurised end of the intake for reuse. These are common in motorsport vehicles.

In contrast, the second type of dump valve, a blow-off valve (BOV), releases the pressurised air via a vent directly into the atmosphere with a loud popping/hissing noise. This type is more frequently used in road vehicles.