If you’ve ever wondered at what speed does your turbo kick in, then you have come to the right place. This article explains exactly what it is that causes your turbo to “kick in” and how to take full control of it with some minor upgrades.
The thing that makes a turbocharger “kick in” is exhaust pressure. This pressure is created by increasing the RPMs (Revolutions per minute), not necessarily the speed. A turbo needs to build enough pressure inside the turbo to spool/spin up the compressor wheel, this pressure is achieved between 1800 to 2200 RPM.
Most everyday turbo cars come stock with a small single turbo that usually operates at between 6-8lbs of boost. The reason for this is that it’s perfect for everyday driving, it provides a little more horsepower, making the car more responsive, while still not being too aggressive for daily driving. Plus it drastically cuts down on emissions due to the turbo basically recycling the exhaust gasses.
Most people over time will find they notice what speed the turbo kicks in in each gear and assume that the turbo is controlled by the speed of the vehicle when in fact it is controlled by the RPM range of the engine.
A small single turbo will generally need between 1800 to 2000 RPM to make it “kick in” or “boost” as it is more commonly known. This is because a small turbocharger will only need a small volume of air/gas to fill the housing of the turbo and create an adequate amount of boost pressure.
A bigger turbocharger, however, will take much more air to fill it thus it will take a higher RPM to create a sufficient amount of boost pressure, it will also take slightly longer for the turbo to build maximum boost pressure, this time delay is known as turbo lag.
Turbo lag is felt when you press down on the accelerator and it feels like the car is not as responsive as it should be, it may also feel sluggish for a second or two after you accelerate, then build full boost and stick you back in the seat.
Bigger turbos will generally need between 2000 – 2500 RPM to build enough boost pressure to get the turbo to kick in and create enough pressure to get the compressor wheel spooling at full speed. This is the reason smaller turbochargers are more popular for most applications if it is quick acceleration with a lower BHP that is needed.
A turbo can kick in at speed as low as 10 MPH under hard acceleration and high RPMs, but on the other hand, you could be driving along at a speed of 60 MPH at 3000 RPM under light acceleration and the turbo will not build boost pressure at all because the engine is not forcing out huge amount of gas as it would under hard acceleration.
Although technically a turbo is always on or at least always spinning, it is not always spinning fast enough to build the correct pressure inside the compressor housing of the turbocharger. To find out all the different types of turbos and how exactly how each one works, you should check out this article, I think you will enjoy it.
A question I get asked a lot is should you let a turbo car warm up and cool down before driving it? And if so, how do you do it? Well, the answer is simple. If the ambient temperature is below...