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What Is Boost Threshold & Why Does It Matter?

What Is Boost Threshold & Why Does It Matter?

You put time and effort into installing your brand-new turbocharger, eager to take it for a spin. You find the perfect strip of road and put your pedal to the metal. Suddenly, you realize nothing is happening, and you assume your vehicle isn’t responding. Before you jump to the conclusion that you have a faulty turbocharger, you should take a deeper look at what might be happening.

The question you should ask is, “What is boost threshold and why does it matter?” By finding the answers to this question, you’ll have a deeper understanding of the importance of knowing your RPM and getting that boost of power you’ve been craving. So read on to get back out on the road without issues.

Understanding Boost Threshold

You may have asked yourself what boost threshold is and why it matters many times, but it isn’t very complicated. Boost threshold applies solely to lower RPM levels. There isn’t enough exhaust gas pressure at the lowest RPM levels to spin the turbocharger and create the necessary boost. However, once the engine reaches the boost threshold, gases accumulate and push air into it, making the boost kick.

Boost threshold is the point where your turbocharger becomes ready for spinning, creating enough engine speed that’s efficient to make the necessary positive pressure. Simply put, it’s a level of engine speed to measure the positive manifold pressure. An example of a boost threshold is going around 5 miles per hour in second gear; the tachometer sits around 1,000 RPM. However, a boost won’t occur unless you reach the boost threshold RPM level.

Why Boost Threshold Matters

The higher your RPMs and the more your pistons move, the more exhaust gases they create, thus spooling up the turbo. If your engine doesn’t operate fast enough, the turbo will become starved of the fuel needed to help increase power in your engine. Feeling your engine choke when you accelerate is the result of not providing enough gas flow for the turbocharger to do its job.


Many car enthusiasts often confuse turbo lag and boost threshold. The significant difference is that turbo lag occurs when there’s a momentary delay between when you step on the accelerator and when the turbocharger responds, no matter what RPM you’re at. Meanwhile, the boost threshold occurs at a lower RPM level. So knowing where these situations occur helps you differentiate the two in the future.

Making sure that the turbocharger you’ve installed works optimally comes down to choosing the correct one. TurboTurbos provides proficient and reliable OEM turbos for increasing raw performance and efficiency in your vehicle's engine. Whether you need a replacement or want a quality upgrade, we’ll gladly help you. If you have any questions, please reach out to us today.

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