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What's the difference between Blow Off Valves & Diverter Valves?

If you drive a turbocharged vehicle and have been browsing upgrades, or are just starting to look into the world of turbos, you may have seen parts listed as BOV (Blow Off Valve) and DV (Diverter Valve). Initially, it’s easy to see these parts side by side and assume that they are exactly the same. While they do both operate with the turbo and replace the same part, they actually function very differently and have their own unique applications.

When your turbocharged Volkswagen, Audi, or BMW vehicle is spooling up under heavy acceleration, and then that acceleration stops abruptly during a shift or when you take your foot off the accelerator, that pressurized air from the turbo has nowhere to go, so it heads back towards to the turbocharger, putting tons of pressure on the turbo itself. BOV’s and DV’s help mitigate this pressure by releasing or redirecting that air, which is important for the health and longevity of your turbo system.

When using a BOV, or Blow Off Valve, the pressurized air is released, or ‘blown off’ back into the atmosphere and out of your vehicle's system, which leaves you with the popular whoosh sound that has come to be associated with many turbocharged vehicles. Many people seek out this turbo sound, and have spent time trying to find the best sounding blow off valves. On the other hand, some poeple are not fans of this loud blow off sound, and prefer their vehicle fly a buit more under the radar.

If you are looking for something a bit quieter and more understated, then a DV, or Diverter Valve may be the route for you. A diverter valve, rather than releasing the air out to the atmosphere, re-directs or diverts the air back into the intake, leaving you with a much quieter valve sound. DV's are more common factory options, due to their quiet nature.

Which option you think is better ultimately depends on your build, and your personal taste. One thing to consider is that cars that utilize a MAF system (Mass Airflow System) commonly use a diverter valve from the factory, so switching to a BOV may cause your car to run slightly rich, triggering a check engine light. This can typically be coded out or fixed with a tune, but it may be easier to run an upgraded DV depending on your make and model to avoid the issue entirely.

Ultimately the difference between a BOV and DV comes down to where the air is being diverted. If you like more sound, go BOV, if you like less sound, go DV. It all depends on what you like and what your personal goals are for your build. If you are still confused or have questions regarding which BOV or DV options are best for your vehicle, feel free to contact us!


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