November 19, 2021 Products

3 Quick Steps to Adjust a (BOV) Blow Off Valve?

Video: How to Adjust A BOV

Before You Adjust A BOV

If you have ever wondered how to fine-tune the performance of your valve, check out the video above. Each Blow-off Valve (BOV) or Bypass Valve (BPV) needs to be adjusted to suit the vehicle it is mounted.

Vee Ports, Supersonics and Dual Ports

The aim of the adjustment on Vee Ports, Supersonics and Dual Ports is to make sure that the piston is hard closed at idle and that the piston closes fast enough to minimise backfiring and not stall the engine.

Plumb Back

Equipped with a spring, Plumb Back BOVs are designed to keep the piston open at engine idle. Hence, the cap can be left in the middle position.

Adjusting BOV

How to adjust a BOV?

  1. To Adjust the BOV, rotate the cap, this increases the spring force on the piston,
  2. Rotate the cap clockwise in the direction of hard as marked on the top of the lid.
  3. To decrease the spring force on the piston. Rotate the cap anti-clockwise in the direction of soft as marked on the top of the lid.
How to adjust a blow-off valve

Quick and Easy Steps When Adjusting a BOV or BPV

  1. Start with the BOV cap at the top soft position. Note: The edge of the cap should completely cover the indicator O-Ring.
  2. With the engine at idle, the exhaust port should be closed off by the piston, and therefore the piston should be hard against the seat and not floating or moving.
  3. Free rev the engine and back off quickly. However, the engine should return to average idle speed if the engine drops below idle or stalls. Go ahead and Increase the spring tension by one turn.
  4. Repeat this process until the engine free revs and returns to average idle speed.
  5. Test drive the car and ensure that the engine has minimal backfiring and no stalling when decelerating or changing gears. If you notice backfiring is excessive or stalling, check all connections made during the installation. Otherwise, increase the spring tension.


If you have installed a vent-to-atmosphere BOV and your engine has started to dip below normal idle and stalling, follow these steps:

BOV Troubleshooting Steps

  1. Firstly, check that the BOV is closed at idle if the BOV is not completed at idle. There’s a good chance the spring tension may need to be increased, or the BOV might need a heavy-duty spring.
  2. Next, check the vacuum hose for splits, cracks, loose connection, kinking or any obstruction. It would be best to replace the old or tired hose’s, and it is also essential to know these hoses may collapse under a vacuum causing an obstruction.
  3. Lastly, with the engine running, remove the vacuum/pressure hose from the nipple in the cap of the BOV. You should hear a loud hissing sound. The engine should idle poorly. Double-check by covering the end of the hose with your finger. If this does not occur, the hose could be blocked or crimped. Thoroughly check the hose and replace it if necessary.
BOV Troubleshooting

If the stalling dipping idle is still occurring follow these steps:

  1. First, ensure that the vacuum/pressure source is not shared and that the vacuum source is directly from the inlet manifold.
  2. Next, check the seal between the adapter and the BOV – ensure that there is no gap between the BOV base and the weld flange.
  3. Lastly, check the join between the adapter and the intercooler pipe for leaking.
BOV Troubleshooting

Here is a handy self-help guide to helping you with your Turbosmart install and answers to some of the most frequently asked questions we get here. Turbosmart recommends that you get your products fitted and tuned by a qualified technician. If you choose to install the product yourself, ensure you have all the necessary tools and technical knowledge required to perform this task.

Thank you for picking up the latest Turbosmart catalogue. As we look back on 22 fantastic years of innovation and growth, we continue to look towards the future as we release some revolutionary new products that will cement our reputation as an innovator and market leaders.

Please contact us here and fill out a quick form so that our team can efficiently help you!

Custom setup and need advice?

Try our Product Advisor! This tool is designed to help you choose the right product for your project & help you choose the right Wastegate, Blow off Valve and fuel Pressure Regulator.

Find products to suit your car

Contact Turbosmart to see if we have products to suit your car on the way or other solutions to help! If you have a new car we don't cover, you can also request a new product.
The last few years have been a little crazy for everyone, and we’re not immune - but we have managed to expand our product range as well as our manufacturing and distribution footprint. We’ve continued to innovate and keep our team and their families safe in uncertain times.

Turbosmart products are all manufactured in-house in our Sydney, Australia Head Office. We’ve been able to support our customers throughout these challenging times seamlessly. Despite the challenges of distance, we always continued to keep the demands and expectations of our customers our top priority, making sure our solutions are in stock & well supported where & when our customers need them!
Nic Cooper Ceo & Founder
Nic Cooper
CEO & Founder


Engineered to Win!

ProPort by Turbosmart is a 54mm (2.13in) Blow Off Valve with a tiny footprint and massive flow. The ProPort flows 420 cfm, which is enough for 3500 HP and is in a league of its own, standing 30mm (1.2in) lower than PowerPort while flowing over 25% more than the Market leading 50mm RacePort.

Turbosmart Blow-off Valve Range

Engineered to Win!

Turbosmart has manufactured the Blow-off Valve (BOV) Range with a focus on performance and reliability.

About Turbosmart

From our humble beginnings to establishing ourselves as a global brand, Turbosmart is well on track to lead the future in turbo technology.

Our engineers build and track test all products in-house. Therefore, we ensure we’re continuously producing the highest quality blow off valves, wastegates, boost controllers, gauges, pressure regulators, and hoses. Furthermore, our products are designed and built for both track and street applications.

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