This month, we will be discussing the fundamentals of how a turbocharger operates! It is much more complex than exhaust gas enters the turbo, some magic occurs and you go faster.
The turbocharger assembly is cast inline with the exhaust manifolds, and is connected by tubing to feed the compressed air into the engine's cylinders. In a way, a turbocharger is similar to a piston engine itself; from start to finish, the process is, exhaust gases enter the turbocharger from the manifolds. That flowing exhaust gas spins a turbine inside the turbocharger. That turbine is cast onto a shaft that has another compressor turbine on that same shaft, separated by the turbocharger housing half. The compressor turbine, in turn, sucks in more air than an engine naturally could, so much so, that it creates a positive pressure of air, or "boost". Boost is measured in psi. The extra air that is pushed into the cylinders, allows more fuel to be injected in an efficient manner and also creates a higher compression ratio, both creating significantly more horsepower and torque.
Now, this may seem like a simple process after understanding how it works, however it takes very precise tuning and software in the engine to successfully accomplish this task. Most turbocharged gasoline engines run anywhere from 10psi to 30 psi. If fuel injection, boost control, or ignition timing is slightly off with that much pressure, major engine damage can occur. The other complimentary side of software with a turbocharged engine is that changing the software tune for your engine can significantly increase the performance of your engine without changing any hard parts. Another key factor in making any turbocharger efficient is ensuring the compressed air is as cold as possible. Cold air is so important because it is much denser than hot air is. The denser the air charge is, the more efficient it is in burning fuel. So the cooler the air, the better the performance. To achieve a cold air charge, the tubing from the turbo compressor to the engine intake has a inter cooler heat exchanger in the middle that removes the extra heat and disperses it to the ambient air. Another precision tuning component in a turbocharged system is the Blow-off Valve (BOV). This valve's purpose is to alleviate excessive boost pressure back into the atmosphere. Many people will recognize the high pitched whistle that occurs from the BOV. When the engine throttle is released, a vacuum forms in the intake manifold, this vacuum causes a small valve inside of the BOV to lift which releases the excess pressure into the atmosphere creating the stereotypical high pitched noise that you would hear while shifting. In some cases, such as BMW turbo systems, they utilize a complex system of tubing that will actually recirculate the extra air back into the turbocharger system. While this makes the system much more efficient and eliminates any waste, unfortunately this means you will not hear the high pitched whistle while shifting unless modifications are performed.
We hope you've gained a better understanding of how a turbocharged engine works, and as always, if you believe your car's turbocharging system is experiencing a malfunction do not hesitate to contact us at 623-776-6126. Or stop by at 8335 W Sherman St Suite #200 Tolleson AZ 85353