Blow off valve
Universal Blow off Valve If you want to adapt the valve size to your engine according to your own specifications.
Model adapted Blow off valve If you want a model adapted relief valve.
Products
Hurricane motorsport Intake manifold safety valve
Adjustable opening pressure 56-85 psi / 4-6 bar
In stock
Hurricane motorsport Intake manifold safety valve
Adjustable opening pressure 56-85 psi / 4-6 bar
In stock
Blow off valve, Diverter valve
Why change to another blow off valve when the oem is already installed?
The reasons can be several, but here we address a few:
Flow
Pressure
Sound
Placement
Flow
These values are guidelines for maximum flow. In practice, this is not always the case. Therefore, a larger valve than it can theoretically flow is used to have margin.
~30mm up to ~600hp
~40mm up to ~800hp
~50mm up to ~2500hp
~60mm up to ~3000hp
Pressure
Sometimes the original valve is not able to handle increased pressure. This may be due to wear and tear over time or construction.
Sound
An OEM valve must be as quiet as possible. Often this is constructed of plastic and leads the air back into the system. Then it is said to be recirculating. An aftermarket dump valve often has a metal construction and then has a different sound. Some valves are designed to release excess pressure outside the system. This is called open or atmospheric blow off valve.
"Turbo flutter"
This is when the accelerator pedal is released and excess pressure cannot be evacuated through the relief valve completely. Then the pressure can only evacuate through the turbo's compressor wheel and because it spins, a so-called "flutter" sound will occur. Be sure to use a suitable blow off valve that does not create this noise as it slows down the turbo with longer spool up time as a result. It is also harmful to the turbo.
Mounting
Rebuilding the engine may mean that the original valve must be moved. This is often a reason to change to a different relief valve. This can both have a welding connection that must be welded. Then the welding flange is almost always included when purchasing a dump valve. Option two is hose connection. Then you simply use a T-piece to join the valve in the system.
Summary
Placement, assembly, flow and pressure are the factors that mostly affect how much power a blow off valve can handle or how much it flow.
The dump valve is open at idle
You need a stiffer spring as the engine vacuum overcomes the force of the spring.
Spring
Guidelines for selecting spring pressure.
2psi: Only used for some supercharged engines
6psi spring for vacuum of: -0.25 bar to 0.4 bar.
8psi spring for vacuum of: -0.4 bar to -0.5 bar.
10psi spring for vacuum of: -0.5 bar to -0.65 bar.
11psi spring for vacuum of: -0.65 bar to -0.7 bar.
12psi spring for vacuum of: -0.7 bar to -0.8 bar.