---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Sat 08/21/04: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 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) ________________________________ Message 1 _____________________________________ Time: 06:23:47 AM PST US From: "Gary Casey" Subject: Engines-List: Re: Pumping Losses vs Carb Heat! --> Engines-List message posted by: "Gary Casey" <> 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 _____________________________________ Time: 07:43:33 AM PST US From: "Vic Jacko" Subject: Re: Engines-List: Re: Pumping Losses vs Carb Heat! --> Engines-List message posted by: "Vic Jacko" 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" Subject: Re: Engines-List: Re: Pumping Losses vs Carb Heat! > --> Engines-List message posted by: "steve korney" > > 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 > > Get ready for school! Find articles, homework help and more in the Back to > >