High Carb Air Temps

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Salty57
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High Carb Air Temps

Post by Salty57 »

Last couple of flights in the P-47, I've noticed that the carb air temp remains pegged to the high side even though I open the Intercooler shutter doors full open. Last night I climbed to 25K altitude and left the Intercooler in neutral position. I saw no outward change in the carb air temp gage, stilled pegged to the high side. Using shift 2 to bring up the menu, it shows that the temp is 34 degrees so it wasn't tracking to the gage. This didn't seem to impact the engine operation as far as I could tell, but I expected that the temp reading would go down at altitude and normal cruise settings?

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Scott - A2A
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Re: High Carb Air Temps

Post by Scott - A2A »

Are you running the turbo too high? What if you have the turbo completely off just to test?

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Salty57
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Re: High Carb Air Temps

Post by Salty57 »

Scott,
I initiated turbo over 10K altitude, but never exceeded 15k rpm during climb. During cruise, I believe it was around 10k rpm. My observation was that from the takeoff to landing, the carb temp remained in the same high position. The gage never seemed to move to me at all.

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Scott - A2A
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Re: High Carb Air Temps

Post by Scott - A2A »

But does the temp go down if you turn the turbo off?
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Salty57
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Re: High Carb Air Temps

Post by Salty57 »

In my descent, I shut down turbo, but I did not see the temperature decline at all. Do you mean shut down the turbo at altitude to see if the temp will drop? I would have to try another flight to see? What action do you recommend? I'll try to do it and see.

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Scott - A2A
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Re: High Carb Air Temps

Post by Scott - A2A »

I just did some tests. I could keep the temps inside the green on a standard day with climb power (42" and 2550RPM). Remember, the supercharger and turbocharger heat the air up a lot.

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Salty57
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Re: High Carb Air Temps

Post by Salty57 »

Interesting, my OAT was 72 F at West Malling airfield in GB. My climb was 42 " MP and 2550 RPM up to 25K altitude. Ground to 10K, was at these values with intercooler not totally open but close. At 25k, leveled off, reduced to 32" MP and 2150 RPM with turbo active. I didn't see any fluctuation on the carb air temp. I'll try another flight tonight and look more closely to see.

dacamp66
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Re: High Carb Air Temps

Post by dacamp66 »

the way i fly her is to leave the turbo off until i get to an an altitude that i cannot maintain recommended power with throttle alone (+/- 16,000 ASL IIRC); once the throttle is pegged and the MP continues to drop as i climb, (note: i do not use excessive power, i only "creep" the throttle up to maintain recommended settings) then and ONLY then do i start using the turbo lever (kind of like a "high altitude throttle") if your problem is happening during a climb, try dropping your nose a little so she starts to build up speed, this MIGHT increase flow through the intercooler. (remember, the "jug" was built as a high altitude, high speed escort bird, she LIKES to go fast) also despite the fact that you lowered the nose a bit, after a while you may notice your rate of climb start to go back up; this is because you are developing more lift ( you can create more lift two ways A. increase the wing's angle of attack (pitch nose up for a steeper, slower speed climb) or B. increase volume of air moved over the wing per unit of time (pitch nose only a LITTLE up for a flatter, higher speed climb) i personally much prefer B myself) hope this helps.
Orville's law: when the altitude of the ground at your current location exceeds the altitude of your aircraft, you have most assuredly crashed.

n421nj
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Re: High Carb Air Temps

Post by n421nj »

Did you ever figure out what the problem was?
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