Today's Message Index:
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1. 06:23 AM - Re: Pumping Losses vs Carb Heat! (Gary Casey)
2. 07:43 AM - Re: Re: Pumping Losses vs Carb Heat! (Vic Jacko)
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Subject: | Re: Pumping Losses vs Carb Heat! |
--> Engines-List message posted by: "Gary Casey" <glcasey@adelphia.net>
<<Does the heat muff make the air turn or twist or slow down in any way as
it
picks up the heat......I think its the same as closing the throttle body a
small amount as far as pumping efficiency goes...
Best... Steve>>
You have a point in that there is some pressure loss in the air heating
plumbing. However, that is probably fairly low and the air filter is
bypassed by the heat control, so it may be nearly a break-even. Regardless
the pressure drop upstream of the throttle is in the inches of water range
(less than 5 for sure), while the pressure drop across the throttle is in
the inches of mercury range because the engine has to be throttled to
maintain the desired power. The net result, I'm sure is less overall
pumping loss with carb heat than without. And the improved air/fuel mixing
is a bonus that may be as or more important than the reduced pumping loss.
We found many, many years ago on automotive carburetor systems that higher
inlet air temperatures improved lots of things. Except power and detonation
resistance.
Gary Casey
Message 2
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Subject: | Re: Pumping Losses vs Carb Heat! |
--> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
A valid point Steve and I think Gary is probably correct in that the losses
would be slight.
The end result is this:
If you want power then you want the fuel charge to be as cold and dense as
possible but if you want efficiency the I am in Gary's corner and will want
the heated mixture for better fuel distribution, less pumping losses due to
more throttle opening, thus more efficient operation.
There may be a trade off using a FADEC or MP advance electronic ignition
system such as Lightspeed Engineering. Less MP actually advances the spark
and allows for more efficient burning of the fuel charge. But if one fly's
at high altitude the manifold pressure drops anyhow so maybe we can have
the best of both worlds.
Vic
From: "steve korney" <s_korney@hotmail.com>
Subject: Re: Engines-List: Re: Pumping Losses vs Carb Heat!
> --> Engines-List message posted by: "steve korney" <s_korney@hotmail.com>
>
> Vic...
>
>
> Does the heat muff make the air turn or twist or slow down in any way as
it
> picks up the heat......I think its the same as closing the throttle body a
> small amount as far as pumping effeciency goes...
>
>
> Best... Steve
>
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