Let’s face it, whether you want to admit it or not, the sound of a blow-off valve is one of the cooler things in the automotive space. While it’s usually only associated with turbocharged engines, ProCharger has a line of blow-off valves for various applications of their centrifugal superchargers. As much as we’d all like to pretend that the sound the valve makes doesn’t matter, it does.
ProCharger knows this. And so they decided to take their entire lineup of blow-off valves, plumb them into a running engine, and have them sing the song of their people, in order to record the sounds. While there are different applications for each valve, and purchasing a valve based on sound alone is the wrong move, this is intended to give you an inside look at something you normally wouldn’t get to see, err… hear (since blow-off valves are usually tucked away in a noisy engine bay).
In the video, ProCharger’s Erik Radzins discusses more than just sounds, first discussing the differences between a blow-off valve and a bypass valve. Both valves perform similar functions — they vent boost pressure from your intake tract when the throttle blade closes. However, they accomplish the task in slightly different ways. A blow-off valve, as the name implies, takes the boost and blows it out into the atmosphere, which is why they are sometimes referred to as “vent to atmosphere” valves.
A bypass valve, on the other hand, is sometimes called a recirculating valve, because it takes the pressurized air from between the supercharger and throttle body, and vents it back into the pre-supercharger intake tract. This is only necessary in a draw-through mass-airflow meter setup, as venting metered air out into the atmosphere can cause overly rich conditions.
So that distinction made, Radzins moves on to the main event, what everyone came for — the blow-off valve sounds. By plumbing all five of the company’s blow-off valve offerings — the ProFlow, Bullet, Race, Competition, and ProRace — into a single tube on the company’s P-1X-equipped 2018 Mustang GT, he is able to selectively activate and deactivate the valves one at a time to give a solid representation of each one’s unique sound profile.
What do they sound like? Well, just watch the video and find out.