If your car is turbocharged, or you’ve considered modifying your vehicle to have a turbo, you’ve probably heard of blow off valves before. While everyone will be quick to tell you that you need one, very few will elaborate on why or what these valves even do. That’s why we’re here today to answer five of the most common questions we get asked about these small but mighty valves:
What Is A Blow Off Valve?
Sometimes referred to as a dump valve or diverter valve, a blow off valve is used to relieve the pressure that would otherwise be fed back to your turbocharger or motor. They help prevent damage to your system and can increase the longevity of your vehicle. For those interested in the “smiles per mile” value that new parts can add, blow off valves also change how your vehicle sounds in a way that many find quite pleasing.
Does My Turbo Need One?
Short answer: Yes. That fluttering noise turbocharged cars make is sometimes a sign of built-up pressure, which can be causing serious damage to the engine and turbo unit. Technically referred to as compressor surge, this noise generally arises when the driver suddenly drops acceleration (think turning a sharp corner, shifting gears, etc.), closing the throttle. This can cause stress to the turbo as it is no longer able to operate efficiently – this is why you get the flutter. A blow off valve helps prevent the build-up of pressure that causes this issue by either releasing it into the atmosphere (that’s where the standard turbo sound comes from) or by recirculation it back through the system in a harmless manner.
Does My Car Need A Turbo To Have A Blow Off Valve?
Yup. Because the purpose of a blow off valve is purely to release excess pressure from a turbo system, they don’t do anything for a standard vehicle. In many cases, you won’t even be able to fit one successfully, but if you do somehow manage it, all you’ll end up with is an expensive audio accessory. If you really want the sound, you’ll need to upgrade to a turbo system.
Do Blow Off Valves Increase Horsepower?
No. While you will most likely experience enhanced performance as your system can run more efficiently with a quality blow off valve incorporated, they do not technically add any horsepower (which is why they don’t appear on horsepower boosting lists). We’re talking completely different areas of modification here, so if someone is telling you they can generate extra horsepower just by adding one in, walk away. There’s a big difference between an increase in performance and an increase in ponies.
Did My Stock Turbo Vehicle Come With One?
Most vehicles that roll off the factory floor with turbo as a standard feature will have some form of blow off valve included. However, they tend to be of lower quality than an aftermarket fitting, and not all turbocharged vehicles are equipped with one from new. If you are unsure whether your vehicle has one, your owner’s manual is a good place to start your search for information. If you are experiencing flutter, we recommend upgrading to an aftermarket unit, even if your vehicle came with a blow off value as stock.
So there you have it, answers to five of the most commonly asked questions about blow off valves.
