What is a compressor bypass valve?

F-DIESEL TURBO & FUEL INJECTION SYSTEM 26/6/2014 9:53:10 pm

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What is a compressor bypass valve?

Since a turbocharger’s drive energy is provided by the exhaust gases and its operational speed is dictated by engine load, a turbocharger has a very dynamic operating speed range. When you are sitting still in traffic with your car at idle speed, the turbocharger is spinning at about 1/8th of it total capability. Once you start to accelerate by opening the throttle its speed increases dramatically. In most cases it approaches 100,000 rpm or greater. As you reach your comfortable speed and let off the throttle, the throttle plate partially closes to reduce the amount of air feeding the engine, but the turbochargers rotational speed carries a lot of inertia and once the throttle is closed the result is a pressure spike generated when the compressed air has nowhere to go. The job of the compressor bypass valve is to relieve that pressure spike by bleeding off the unwanted air and redirecting back into the air filter assembly. This keeps the turbocharger from enduring high amounts of load due to the rapidly changing rpm that is encountered while driving.

What is an intercooler?

The turbocharger is centrifugal compressor, and one of the by products of compressing air is the heat generated by that actual act of compression. The design of the blades of today’s turbochargers compressor wheels make them very efficient, providing for the means of filling the engine with a large amount of air very quickly. The high operational speeds of the compressor introduces a significant amount of heat into the air that needs to be reduced before it enters the engine, this is the job of the intercooler. The intercooler in most cars uses ambient air passing over a radiator type core to cool the charged air. Since the compressed air directly out of the turbocharger can approach 300*F, and most outside air temperatures are 100*F or less, the ambient air does a really good job cooling the intercooler and charged air before it reaches the engine.

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