Turbo "Normalization" vs a steady hand

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yankeeclipper

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Jun 1, 2009
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Is there a difference, from the engine's point of view, between a turbo-normalized engine and a pilot that chooses to never exceed 30" on a conventional turbo?
 

Midniteoyl

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Sep 3, 2003
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Indiana
What do you mean? You planing on having a turbo run at full boost and then control MAP via throttle? Thats a pretty inefficient way to do it as you are heating up the intake air unnecessarily, increasing throttle losses, increasing turbo wear, etc.. Plus, having full boost all the time means you cant really have it high enough to normalize at any great altitude..

If you mean that you are going to control the wastegate yourself, sure, you can do that but its just another thing to make you keep your eyes in the cockpit adding workload.

Best is to auto normalize..

Actually, I do believe that even a 'normalized' engine actually runs at a couple pounds boost most of the time..
 

yankeeclipper

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Jun 1, 2009
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Northeast.
As I understand it, a T-N'd engine merely sets a wastegate to open above SL pressure, or roughly 30". So no boost above what an NA aircraft gets at SL. The intention is to give you that SL performance up to 20k ft. without the reduced engine life (or, albeit, extra power) of a boosted (33"+ MP) engine.

So what's the difference between a T-N'd engine and a turbo that isn't ever run above 30"?
 

Dan Thomas

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Sep 17, 2008
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5,078
As I understand it, a T-N'd engine merely sets a wastegate to open above SL pressure, or roughly 30". So no boost above what an NA aircraft gets at SL. The intention is to give you that SL performance up to 20k ft. without the reduced engine life (or, albeit, extra power) of a boosted (33"+ MP) engine.

So what's the difference between a T-N'd engine and a turbo that isn't ever run above 30"?
No difference, except that the pilot could overboost it if it has the manual wastegate.

Manual gates were common enough on certified airplanes. The Turbo 182RG (TR182) has such a setup, and it is a major maintenance consideration. That linkage has numerous sliding and pivoting parts at the carb and a cable off that to operate the wastegate. All of it needs cleaning occasionally, it makes the throttle stiff, and the pilot has to watch the MP on takeoff and keep applying more throttle as he climbs. The first half or so of the throttle knob travel opens the carb's throttle plate, and the last half closes the wastegate.
 
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