Guide to MK7 Blow Off Valves
With the introduction of the MK7 platform in 2013, drivers enjoyed a more efficient engine, advanced electronics systems, and improved styling just to name a few. However, one of the largest advances for enthusiasts and gear heads was an increased turbo size which allowed for higher power output and more potential for effective aftermarket tuning.
With a bigger turbo comes higher boost pressure which in turn comes with the potential for aggressive turbo noises. While entirely subjective, many agree that a Blow off Valve (BOV) causes a sporty turbo noise. This noise does not happen on stock MK7s because of Volkswagen's choice of using Diverter Valve (DV) instead of a BOV.
So how do Diverter Valves work?
When an engine is under throttle the turbo typically builds up boost in the charge pipes of the intake and intercooler piping while also releasing the pressure through the exhaust. When the throttle is depressed and the engine no longer requires boost, it needs to expel the left over air in the system before able to spin the turbo again or the turbo will risk a "stall". Diverter Valves achieve this by opening their mechanism to recirculate this leftover air to the beginning of the intake system. While this method is effective, it doesn't produce the same level of noise many enthusiasts desire.
How do Blow Off Valves Work?
Unlike DVs where the mechanism recirculates the leftover air, BOVs "vent to atmosphere". Which simply means the air is not recirculated but rather disposed of back into the air instead of the intake system. This causes a large "woosh" sound to be produced from the air exiting the BOV.
Which should I pick?
For the majority of applications, we suggest using your stock DV setup because of its proven ability to successfully and reliably recirculate air. However, for those looking to generate higher horsepower and boost levels, or those who simply want that coveted sound, we recommend looking into installing a BOV. Regardless, now that you understand the difference you'll be able to make an informed decision.
How to install a BOV in your MK7 (DIY)