Blow off valves

Blow off valves are used on turbocharged cars to relieve pressure in the intake and boost pipe system when the throttle is released and the throttle plate closes. The valve helps direct excess pressure away so that the turbo and the rest of the system are not unnecessarily stressed between gear changes and during rapid changes in load.

A blow off valve can be relevant both on optimised road cars, motorsport projects, and more custom-built turbo setups. In many cases, they are chosen both for function and response, but also because they are a standard part of many performance builds with boost pipes, intercooler, and upgraded turbo. Depending on the setup, there may be differences in which type of valve fits best, including an open blow off valve or a recirculating solution.

When choosing a blow off valve, it is important to look at more than just appearance and sound. The valve needs to match the engine setup, boost pressure, vacuum signal, pipe routing, and the way the car is used. Installation, flange type, and placement in the boost system also matter for how the solution works in practice.