For a BRV to work consistently and not leak, tolerances must be held to an extremely high standard. The EVP BRV body, cap and piston are precision CNC machined from billet aluminum with tolerances that approach within .0003". The sliding components are hard anodized and coated so the BRV will last the lifetime of the engine. For each vehicle / engine type EVO make BRV kits for, the spring rates are properly matched for optimum performance.
What's the Difference Between a Blow Off Valve and a Boost Recirculating Valve?
A blow-off valve (BOV) and boost recirculating valve (BRV) are very similar mechanically and perform similar jobs; they just do it in two different ways. Both valve bodies are attached to the charge tube, and both are designed to release turbocharger pressurized air once the throttle body closes to prevent turbocharger compressor "stalling". Both valves are also connected to a manifold vacuum / pressure port so when the throttle body closes, the manifold vacuum pulls the BRV/BOV piston open and when the throttle blade opens and the manifold sees positive pressure, the piston of the BOV/BRV valve closes. When the BRV valve is open, the built-up pressure in the charge air system gets diverted back to the fresh air side of the turbocharger and helps to keep the turbocharger spooled up when the throttle is being modulated from part throttle to wide open throttle then back to part throttle. This makes the boost response crisper in these throttle modulation situations. A BOV is operated the same way but instead of venting the built-up pressure back to the turbo inlet, a BOV vents most of this pressurized air to the atmosphere and the notorious “Pssshh” sound is emitted.
