The short answer is, a turbocharger spins really, really darn fast. The better answer involves understanding why that is so important to the engine the turbocharger is attached to.
The typical car engine is rated usually in the range of approximately 5,000 rotations per minute. It can be higher, but that’s definitely getting into the redline area of operation. A turbocharger fan, in comparison, spins at approximately 150,000 RPMs, or basically 30 times harder. Obviously, that generates a lot of energy, and all that activity has to go somewhere. This is what makes a turbocharger such a gamechanger for the engine it is attached to.
Technical Range of Operation
Specifically, a turbocharger operates in a range of speed levels, depending on how hard the related car engine is working at the time. That range starts at a low end of 80,000 RPMs, and it can reach as much as 200,000 RPMs (or 250,000 RPMs on heavy duty assemblies). The variance of one turbocharger to another is mainly in the construction of the assembly, the parts and make used, and their overall weight.
The speed of the turbocharger really doesn’t begin to manifest until it is fully activated. For that to happen, the car engine attached has to be running well above a basic low gear and definitely above idle. Otherwise, the exhaust pressure that is the primary driver of the turbocharger fan simply doesn’t have enough strength to activate the apparatus. However, once the engine is above second gear, the turbocharger really starts to kick in. And as it extrapolates the exhaust pressure, the unit begins to pull more and more air through the intake into the engine, increasing responsiveness. That in turn pushes more pressure from combustion, and the turbocharger fan spins harder and faster again.
The combination of pressured air and increased exhaust gas pressure creates more energy which translates to the engine working harder, hotter and faster. All of those components add up to greater engine strength and performance, as well as going faster with a shorter response time, ergo the “turbo” naming and description. Of course, all of that energy suddenly hitting the engine combustion may be far more than it can handle, which means excess pressure is created. Most modern turbocharger systems also come with a matching pressure release mechanism to allow the unused pressure created to release instead of damaging the affected engine as well.
Shape and Design Borrowed from Earlier Technology
The capability of a turbocharger to spin so fast, at a far greater speed than the engine itself could ever achieve, is possible because of singular function focus as well as the nature of the parts used to fabricate the fan and how it works. The idea of the turbocharger is not a new concept. In fact, before fuel injection was commonplace, carburetors were the standard air mixing device for car engines. This involves a tremendous amount of design to harness the venturi effect, the ability to mix air and fuel to a detail level using air suction and funneling to enhance its effect. The same approach was then applied to a turbocharger, only it uses exhaust gases from the engine to power the turbo fan, which can create more than enough pressure to drive the apparatus.
One would think that the turbocharger fan works by applying the exhaust gas pressure to its blades and then letting it spin. This is incorrect. Instead, what happens is that the exhaust pressure from the engine flows into the compressor of the turbocharger. That forced energy then spins the turbo fan or turbine, which in turn releases the energy, pulling air in and pushing it into the engine chamber for combustion. Of course, all of this amazing ability is only possible as long as the system works and stays together. Over-charging will cause damage and eventually wreck the turbocharger and possibly the engine as well.
Maintenance Prolongs the Life of Turbochargers
Eventually, even the best turbochargers will wear out. At that point, repair and even replacement will be necessary. Probably the most notable sign is the significant drop in sudden power strength the engine used to have when the turbocharger was working correctly. In some cases, significant variation in the car’s ability to hold onto power and maintain it will occur. Other cases realize a losing ability to maintain high speed with the engine; it just can’t hold onto a sustained performance. In the worst cases, the exhaust will push out a lot of smoke from burning too much fuel, and the check engine light can even turn on due to bad air-fuel mixture occurring.
The last particular feature noticed when turbochargers spin fast is an audible whine. This is not a repair issue. As the air is moved through the turbocharger and specifically the compressor, and then out the discharge, the effect is a high-pitched whine that everyone on the road can hear. No surprise, a turbocharged engine is going to catch people’s attention when it zips by running at full force, even with their windows up on the road.
Spinning Fast to a Fault
So again, turbocharger fans can move at extremely high rates of speed, as much as 250,000 RPMs in extreme cases and definitely as high as 200,000 RPMs in mainstream assemblies. That said, they are a high-performance component, which means owners need to anticipate lots of regular maintenance to keep things working optimally. Otherwise, folks just won’t see the full potential out of adding a turbocharger to their vehicle’s engine, no matter how fancy it is.