continuous carburettor heating?

What are the pros and cons of continually heating the carburettor body with
a stream of warm air? Not the inlet air, just the body. The intent is to
minimise the risk of carb-ice, will it have that effect? Will there be
impact on the performance of the engine (Jabiru 3300)?

Rob

What are the pros and cons of continually heating the carburettor body with
a stream of warm air? Not the inlet air, just the body. The intent is to
minimise the risk of carb-ice, will it have that effect? Will there be
impact on the performance of the engine (Jabiru 3300)?

Rob
++++++++++++++++++++++++++++++

Study the Lycoming
It essentially accomplishes this and more
from the way the air & carb are oil heated.

Naturally, additional carb heat is seldom necessary.

Yes, the design does cause some HP loss.


Barnyard BOb - Lycoming 0-320

Yes, the design does cause some HP loss.

And you go looking for a drop in rpm when applying carby heat in most piston
engined aircraft.

Should apply just as much to diesel engines as well based on the performance
difference in my old 4.6 ton underpowered non-turbo diesel truck that goes
like a rocket on cold mornings, and that it can't even get up to 50 mph on
the open road on a summer afternoon.

However many systems also use unfiltered air and this provides a difference
again. The same old truck has a ram air system made from a plastic kitchen
container that "force feeds" the air via a 100mm stormpipe to the air
cleaner system. It makes a difference in "performance" but nowhere near as
much as the four foot high, seven foot wide, tailgate loader that sticks up
at the back like a dirty big air brake!

Depends on where you operate, filtered air does provide some protection to
the engine, and ingestion of dust can cause sudden engine problems.

Hope this helps,
Peter

"Rob Turk" wrote in message ...
What are the pros and cons of continually heating the carburettor body with
a stream of warm air? Not the inlet air, just the body. The intent is to
minimise the risk of carb-ice, will it have that effect? Will there be
impact on the performance of the engine (Jabiru 3300)?

Rob

First thought: using warm air is not a particularly effective way of
heating the carb body. Too many heat transfer processes. Electricity
or hot oil would be more effective, IMHO.

Second Thought: There are several mechanisms involved in carb ice, and
this won't address all of them. Check any of the many articles on
carb ice to see what I mean. The venturi effect and the heat the
vaporizing gas sucks out of the air stream may overcome a hot carb -
among other possible failure scenarios.

Third thought: heating the mixture will reduce it's density, both of
fuel and air, and thus may cut power, BUT it may IMPROVE the
uniformity of the mixture, allowing you to run leaner without
roughness - see the sidebar on this AVWEB article for some sketchey,
but tantalizing details.
http://avweb.com/news/columns/182583-1.html

"Bushy" wrote in message
Should apply just as much to diesel engines as well based on the
performance
difference in my old 4.6 ton underpowered non-turbo diesel truck that goes
like a rocket on cold mornings, and that it can't even get up to 50 mph on
the open road on a summer afternoon.

Diesels have carbuerators?

D.

Diesels have carbuerators?


This one's that old it does!!!!!!! ;)

Point taken, but it does have a decent air preheat box that will allow it to
start on really cold mornings... just turn the key to preheat and let it
warm up the box for a moment.

I was refering to the loss of power with the inlet air being warm rather
than cold and the loss of engine power with heat applied. The same effect of
loss of power is observed when heating the inlet air on a diesel engine or a
petrol fuel injected engine as well as a carby engine.

The example with the old truck is to show that ambient temperature can cause
a reduction in engine power and that a similar reduction in power is
experienced when carby heat is applied.

Hope this helps,
Peter

difference in my old 4.6 ton underpowered non-turbo diesel truck that goes
like a rocket on cold mornings, and that it can't even get up to 50 mph on
the open road on a summer afternoon.

Diesels have carbuerators?

D.
+++++++++++++++++++++++++++++

No, Doug.
But some could have.... carburetors.


Barnyard BOb - can't anybody speel? g

Some old Diesels have carburetors. I have an old road grader with an
International engine that starts on gasoline and then runs on diesel
when you throw a lever that closes a third valve in the head..

On Thu, 02 Sep 2004 16:28:19 -0500, Barnyard BOb -
wrote:



difference in my old 4.6 ton underpowered non-turbo diesel truck that goes
like a rocket on cold mornings, and that it can't even get up to 50 mph on
the open road on a summer afternoon.

Diesels have carbuerators?

D.
+++++++++++++++++++++++++++++

No, Doug.
But some could have.... carburetors.


Barnyard BOb - can't anybody speel? g

"Barnyard BOb -" wrote in message - can't anybody speel? g

Dictionary is boarded up and may not be there when I return as I may have a
new house soon. Get ready for some really atrocious spelling because I'm
spending a few days with my British friends on the backside of the storm.

D.

"Capt.Doug" wrote in message ...
"Barnyard BOb -" wrote in message - can't anybody speel? g

Dictionary is boarded up and may not be there when I return as I may have a
new house soon. Get ready for some really atrocious spelling because I'm
spending a few days with my British friends on the backside of the storm.

D.

Good luck Capt. Hope everything works out as best as it can
considering the storm.

Bryan "The Monk" Chaisone
~ survuved carburetor icing, full-autoed to a farm. thought I'd
bought the farm. my first full touch down auto and I aced it. what
luck.