It's a blow off valve like cars have. It protects the turbo from turbo bark
Its just like he said it eliminates turbo bark. Stock turbos are better because there is less boost. So they dont bark normally when being daily driven. My turbo barks every once in a while they way i drive so i got the bov to make my turbo live a longer happier life.
No throttle plate to suddenly close off, which would make the pressurized air go backwards through the turbo. Our engines keep consuming the pressurized air, just at a slower rate. Hence the little "bark" you hear. BOV's aren't really necessary on our trucks, except for piece of mind for some people and that "cool" sound for others.
It's because diesels don't have throttle plates. They are throttled by fuel, not air. When you chop the throttle on a diesel the remaining pressure either goes into the cylinders or back out of the turbo. It's not as violent because the air doesn't get cut off all at once.
