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At the risk of starting a flame-war, the new Cirrus turbocharged SR22T raises a question I always had . . . just what is the difference between a turbocharged vs. turbonormalized engine? What are the pros and cons of each? *Note - I'm being careful to avoid asking "which is better", just curious about how mechanically they are different and maybe the situations you'd consider one vs. the other. Thanks! |
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The main difference between a turbo-normalized engine and a turbocharged engine is the amount of work the pilot is required to do on each engine. A turbocharged engine is capable of being over-boosted, meaning the manifold pressure is capable of exceeding the upper limits set by the manufacturer. The pilot is required to set the power on takeoff to ensure the engine isn't over-boosted. As the airplane climbs, the pilot is readjusting the settings to keep the engine at peak performance. Much like a pilot of a constant speed prop is adding power to keep the manifold pressure as high as possible. A turbo-normalized engine in essence is capable of making its own changes to keep the engine at peak performance. As Sean C. said, the turbo-normalized engine will keep the manifold at 29.92 and not allow the engine manifold to go higher through the use of the waste gate. From what I have read, the turbo-normalized engine is easier for the pilot to work with. The technologies are so similar that I think the only advantage for the turbo-normalized is the auto adjusting manifold pressure. Without that feature, it would just be a turbo charged engine. |
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Turbo-normalizing is the process of keeping the intake manifold pressure the same pressure through climb. Meaning it keeps the pressure at 29.92 mb as the aircraft climbs. A turbonormalizer system increases the amount of compressed air that is delivered to the engine by controlling how much of the total exhaust gas bypasses the turbocharger. Exhaust bypass is controlled by the waste gate which makes cool noise at least on car engines. From what I know most aircraft engines are considered turbo-normalized because they really can't handle being over pressurized because the engine becomes to hot; cars can handle because they are not air cooled. [Thanks Aircraft Systems class for learning this]. |
