Today's Message Index:
----------------------
1. 12:16 PM - Pumping Losses vs Carb Heat! (Vic Jacko)
2. 04:25 PM - Re: Pumping Losses vs Carb Heat! (Ken Stribling)
3. 05:48 PM - Re: Pumping Losses vs Carb Heat! (Vic Jacko)
Message 1
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| Subject: | Pumping Losses vs Carb Heat! |
--> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
HI list, Maybe the subject title caught your attention.
On a cross country yesterday I experimented with the following: (Lycoming 0-320)
Climbed to 6,500 feet , leveled off and kept the throttle open all the way, added
full carb heat, leaned until the engine started to lose power and then enriched
until it ran smooth. The engine would only pull 2500 RPM in this configuration.
Thesis: The engine thinks it is flying at a higher altitude than 6,500 feet
due to the hot intake air.
Because the carb throttle plate is fully open there are less pumping
losses than a partially closed throttle.
This is supposedly one of the reasons to fly at a higher altitude
to improve efficiency by reducing pumping losses.
If I were to fly at the same altitude without carb heat and leaned
the same I would have to pull back the throttle to
keep the engine at 2500RPM cruise. This would cause some pumping
losses to occur.
I am of the opinion the engine will burn less fuel in the carb
heat configuration due to less pumping losses!
Not having a fuel flow device I could not come up with any empirical data to support
my thesis.
This procedure may not be desirable in the hot summer months but may have some
merit in the cooler or colder times of the year.
Comments from any of you engineheads! (motor heads as it is called in NASCAR)
Thanks for your critical and non-critical remarks.
Vic
Message 2
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| Subject: | Pumping Losses vs Carb Heat! |
--> Engines-List message posted by: "Ken Stribling" <ken@striblingranch.com>
With carb heat applied you may be starving the engine of the air flow it
needs.
-----Original Message-----
From: owner-engines-list-server@matronics.com
[mailto:owner-engines-list-server@matronics.com] On Behalf Of Vic Jacko
Subject: Engines-List: Pumping Losses vs Carb Heat!
--> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
HI list, Maybe the subject title caught your attention.
On a cross country yesterday I experimented with the following:
(Lycoming 0-320)
Climbed to 6,500 feet , leveled off and kept the throttle open all the
way, added full carb heat, leaned until the engine started to lose
power and then enriched until it ran smooth. The engine would only
pull 2500 RPM in this configuration.
Thesis: The engine thinks it is flying at a higher altitude than
6,500 feet due to the hot intake air.
Because the carb throttle plate is fully open there are
less pumping losses than a partially closed throttle.
This is supposedly one of the reasons to fly at a
higher altitude to improve efficiency by reducing pumping losses.
If I were to fly at the same altitude without carb heat
and leaned the same I would have to pull back the throttle to
keep the engine at 2500RPM cruise. This would cause
some pumping losses to occur.
I am of the opinion the engine will burn less fuel in
the carb heat configuration due to less pumping losses!
Not having a fuel flow device I could not come up with any empirical
data to support my thesis.
This procedure may not be desirable in the hot summer months but may
have some merit in the cooler or colder times of the year.
Comments from any of you engineheads! (motor heads as it is called in
NASCAR)
Thanks for your critical and non-critical remarks.
Vic
==
==
==
==
Message 3
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| Subject: | Re: Pumping Losses vs Carb Heat! |
--> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
Ken, you may have a point as the air is hotter and there is no ram effect,
but the engine will produce the same power at 2500 RPM with or without carb
heat if the throttle and mixture are adjusted to produce the 2500 RPM
----- Original Message -----
From: "Ken Stribling" <ken@striblingranch.com>
Subject: RE: Engines-List: Pumping Losses vs Carb Heat!
> --> Engines-List message posted by: "Ken Stribling"
<ken@striblingranch.com>
>
> With carb heat applied you may be starving the engine of the air flow it
> needs.
>
> -----Original Message-----
> From: owner-engines-list-server@matronics.com
> [mailto:owner-engines-list-server@matronics.com] On Behalf Of Vic Jacko
> To: engines-list@matronics.com
> Subject: Engines-List: Pumping Losses vs Carb Heat!
>
> --> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
>
> HI list, Maybe the subject title caught your attention.
>
> On a cross country yesterday I experimented with the following:
> (Lycoming 0-320)
>
> Climbed to 6,500 feet , leveled off and kept the throttle open all the
> way, added full carb heat, leaned until the engine started to lose
> power and then enriched until it ran smooth. The engine would only
> pull 2500 RPM in this configuration.
>
> Thesis: The engine thinks it is flying at a higher altitude than
> 6,500 feet due to the hot intake air.
>
> Because the carb throttle plate is fully open there are
> less pumping losses than a partially closed throttle.
> This is supposedly one of the reasons to fly at a
> higher altitude to improve efficiency by reducing pumping losses.
>
> If I were to fly at the same altitude without carb heat
> and leaned the same I would have to pull back the throttle to
> keep the engine at 2500RPM cruise. This would cause
> some pumping losses to occur.
>
> I am of the opinion the engine will burn less fuel in
> the carb heat configuration due to less pumping losses!
>
>
> Not having a fuel flow device I could not come up with any empirical
> data to support my thesis.
>
> This procedure may not be desirable in the hot summer months but may
> have some merit in the cooler or colder times of the year.
>
> Comments from any of you engineheads! (motor heads as it is called in
> NASCAR)
>
> Thanks for your critical and non-critical remarks.
>
> Vic
>
>
> ==
> ==
> ==
> ==
>
>
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