Car guys and girls know whether a car is turbocharged just by listening to the sound it makes. Turbos create specific noises, no matter if the car runs on gasoline or diesel. The most popular is the “stututu” sound, which most enthusiasts consider music to their ears. But what causes this sound? It’s called turbo flutter.
Here, we’ll talk about turbo flutter, what causes it, whether it’s bad or good, and much more. We’ll start with the basics and work our way from there.
Turbo flutter is also known as compressor surge. The “stututu” sound, that is turbo flutter, is the sound of air escaping through the turbo. Keep in mind that not all turbocharged cars have turbo flutter. In fact, it’s likely that you’ll notice turbo flutter only on modified cars. This is because cars with a turbocharger have a blow-off valve that blocks the excess air from reaching back to the turbo.
What Causes Turbo Flutter?
The simplest explanation of what causes turbo flutter is excess air returning to the turbo. Let’s go into detail.
Depending on how hard you’re pressing the accelerator, the turbo spins between 80,000 and 200,000 revs per minute. You’ll agree that it’s a fascinatingly high number. Even when the car is idling, the turbo spins at around 40,000 revs. When you press the accelerator, the throttle body opens, providing the engine with more air. When the accelerator isn’t pressed, the throttle body closes, which equals less air coming to the engine.
The way that turbo works is that one side of the impeller in the turbo sucks in cold air, compresses it and sends it to the engine through the intake manifold. The throttle body is located between the engine and the intake manifold, and it’s used to control how much air is fed to the engine depending on how hard you’re pressing on the accelerator pedal.
When the turbo is spinning at 100,000 revs, it sucks in and compresses a pretty large amount of air. The moment you release the accelerator, the throttle body closes and traps compressed air. At this moment, the turbo is still spinning, trying to push more air to the engine through the intake manifold. Because the throttle body is closed, the compressed air can only go back through the turbo, which results in turbo flutter. In most cars, this is fixed by adding a blow-off valve.
The reason why stock cars usually don’t have turbo flutter compared to modified cars is that it doesn’t require a lot of modifications to make turbo flutter. By simply removing the blow-off valve, or replacing it with an aftermarket one that doesn’t have the same capacity will cause turbo flutter. Unfortunately, aside from gaining the sound, turbo flutter doesn’t do anything for performance.
Can Turbo Flutter Damage Your Car?
We’ve already established that turbo flutter doesn’t have any effect on a car’s performance. Aside from creating the recognizable sound, there’s nothing else turbo flutter does that will either increase torque or horsepower.
On the other hand, turbo flutter causes a lot of strain on a turbocharger. Turbos are expensive components, so you’ll have to ask yourself whether you’re willing to risk a four-digit expense for nothing more but sound. The back pressure can cause damage to the internal components of a turbocharger, however, newer generations of turbochargers are durable enough to withstand the added pressure. The problem is when older cars get modified without checking the condition of the turbocharger before removing the blow-off valve.
If a turbocharger isn’t in ideal condition, the back pressure caused by removing a blow-off valve can easily cause damage to the turbo and other internal components of the car. You’ll agree that a modification providing just a familiar sound isn’t worth the risk.
Making Turbo Flutter Or Preventing It
Regardless of the fact that turbo flutter doesn’t improve a car in any way performance-wise, there are a lot of people that deliberately make modifications to their car, just so they can make that signature sound. If you’re one of those people, the simplest and easiest way to get the “stututu” sound from your car is to remove the blow-off valve. Of course, this implies that your car is turbocharged.
The issue here is that you’ll likely need to do this yourself. It’s a simple process, however, a small number of mechanics would agree to do this due to the potential risks that go with it. Removing the blow-off valve is simple, and you’ll also need to plug all the holes that led to it.
The more complicated, and even riskier way of creating turbo flutter is increasing turbocharger pressure while reducing the blow-off valve capacity. This is also a much more expensive modification because you’ll either need a larger turbo, an aftermarket blow-off valve, and commonly ECU tuning. All of this comes with a cost, and regardless of the power gain from the larger turbocharger, there are smarter ways to invest money if you want more power from your car.
If turbo flutter is caused with no modifications to the car, it’s likely your blow-off valve is not functioning properly. In most cases, simply replacing the blow-off valve will eliminate the turbo flutter completely, however, if you’ve made certain modifications to your car and the turbo pressure is larger than factory, you might need to invest in an aftermarket blow-off valve that will have the capacity to take in all the pressure from the intake manifold.
Anti-lag systems are also a good solution to preventing turbo flutter, and aside from eliminating the sound, they will improve the turbo response time, allowing you to accelerate faster. Compared to replacing a single blow-off valve, anti-lag systems are more complex, and a bit more difficult to install. It’s not a recommended modification for regular daily driven cars, but for more extreme applications such as race cars.
Conclusion
If you don’t drive an overly-modified car, turbo flutter shouldn’t concern you too much. Modern turbochargers are built in a way that turbo flutter won’t cause damage. Creating and eliminating turbo flutter is simple with removing or replacing a blow-off valve, and it’s something most people can do themselves.
If you like the sound turbo flutter makes, we say – go for it, but make sure the affected components are in good condition prior to any type of modification.