Supercharger handling

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P40 Master
Airman
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Joined: 26 Mar 2021, 05:33

Supercharger handling

Post by P40 Master »

I've been flying the p51 for a few weeks now and the supercharger setup is confusing me a bit. Leaving it in auto you would think it would switch between high and low automatically. I've found at around 12k I'm having manually switch to high to maintain manifold pressure. Any tips from p51 guru? And I can't start her when she is warm even looking at the prime switch floods her and back to the hangar for a new battery we go. Other than that I'm in love with the mustang and all the other a2a products I use.

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MkIV Hvd
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Joined: 11 Mar 2019, 21:36
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Re: Supercharger handling

Post by MkIV Hvd »

In the auto position, HI blower will kick in automatically around 18-19 thousand feet-ish and you should not be seeing a drop in manifold pressure until shortly before the shift to HI. I regularly miss the drop in the climb, but it's a pretty short period and doesn't drop much before the shift. It doesn't make sense that you're seeing a drop in manifold pressure at all (especially as low as 12,000) until just before the Lo to HI shift. Just thinking...are you running the mixture in RUN? I'm wondering if the auto compensation features don't work if it's in RICH, but that's about the only thing I can think of that *might* cause that behaviour... :?

I don't have a problem starting it when it's warm and usually use a couple of shots of primer. However if you do flood it, just crank it with the mixture in cutoff and the throttle wide open...and be ready to pull the throttle back really quickly... :wink: :mrgreen:

Cheers,
Rob
Rob Wilkinson
A2A: Civilian Mustang, T-6, Bonanza, Comanche, Cub, C182, Spitfire, P-40, Cherokee, P-51 - VATSIM P4 and some other stuff...

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DHenriques_
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Joined: 27 Mar 2009, 08:31
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Re: Supercharger handling

Post by DHenriques_ »

P40 Master wrote: 08 May 2021, 10:13 I've been flying the p51 for a few weeks now and the supercharger setup is confusing me a bit. Leaving it in auto you would think it would switch between high and low automatically. I've found at around 12k I'm having manually switch to high to maintain manifold pressure. Any tips from p51 guru? And I can't start her when she is warm even looking at the prime switch floods her and back to the hangar for a new battery we go. Other than that I'm in love with the mustang and all the other a2a products I use.
Normally in AUTO, the charger should kick in somewhere between 14.5K and 19.5K. Also normally it's a good idea to anticipate the crossover into high blower and reduce the power, make the switch manually then slowly reintroduce the power. This avoids a manifold pressure surge that comes with the automatic switchover.

You can easily overprime the 51 when making a hot start. Just a few seconds will over prime it.
If the engine is hot, just start it with a second of prime . Just hit the switch and think (One Thousand) and let it go.
It is VERY easy to overprime a Mustang!
Dudley Henriques

P40 Master
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Posts: 36
Joined: 26 Mar 2021, 05:33

Re: Supercharger handling

Post by P40 Master »

My apologies its about 15 it starts to drop, I've found myself switching to high manually. I'll try leaving it in auto and trusting that it will change on its own. Thanks for the help much appreciated

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