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jeff(at)rmmm.net Guest
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Posted: Wed Jan 21, 2009 3:07 pm Post subject: Induction Air |
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Hi All,
While I have Gold Rush in for the winter annual I'm considering some
cowl changes. Including closing off the upper NACA use for induction
air on the 912-S and using the lower starboard NACA normally used for
the 914 induction. I seem to remember someone else using that for carb
intake and under cowl carb heat. I'm going to use the same air plenum
with the same filter as now but I will fabricate a side intake to
attach to the top of the plenum and a 2 inch scat tube coming up from
the below NACA. My question is this. I already have the inlet plumed
for this 2 inch tube and not a lot of room to increase it to 3 inch. My
concerns is if the 2 inch would be enough for both carbs. Has anyone
else done this with the 912-S and if so what size of tube did you use?
Best Regards,
Jeff R.
A258 - N128LJ / Gold Rush 175 hours and climbing slowly cause this
winter if frickin could & wet for Tennessee ;o(. Must be al's global
warming!
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topglock(at)cox.net Guest
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Posted: Wed Jan 21, 2009 3:22 pm Post subject: Induction Air |
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Jeff,
It's square inches, my friend. Get out the old pi r squared and figure
the square inches in the duct cross section. Then compare that to the
square inches of the inlet opening.
Jeff
JEFF ROBERTS wrote:
Quote: | Hi All,
While I have Gold Rush in for the winter annual I'm considering some
cowl changes. Including closing off the upper NACA use for induction air
on the 912-S and using the lower starboard NACA normally used for the
914 induction. I seem to remember someone else using that for carb
intake and under cowl carb heat. I'm going to use the same air plenum
with the same filter as now but I will fabricate a side intake to attach
to the top of the plenum and a 2 inch scat tube coming up from the below
NACA. My question is this. I already have the inlet plumed for this 2
inch tube and not a lot of room to increase it to 3 inch. My concerns is
if the 2 inch would be enough for both carbs. Has anyone else done this
with the 912-S and if so what size of tube did you use?
Best Regards,
Jeff R.
A258 - N128LJ / Gold Rush 175 hours and climbing slowly cause this
winter if frickin could & wet for Tennessee ;o(. Must be al's global
warming!
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cptimm(at)telus.net Guest
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Posted: Wed Jan 21, 2009 3:53 pm Post subject: Induction Air |
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Hi Jeff,
I modified my Classic cowling early on, with a starboard NACA inlet on the lower cowling, and started out with a 2" scat tube
to the plenum chamber. This turned out to be too small for the 912S, and it became necessary to enlarge the inlet to 3".
It enabled me ,however, with a home-made 3" to 2" Y , to also supply air to 2 ball vents in the cockpit, as well as making the engine happy.
Peter Timm
# ll0, Classic mono, 912S, 380 hrs
[quote] ---
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air.guerner(at)orange.fr Guest
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Posted: Thu Jan 22, 2009 4:26 am Post subject: Induction Air |
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Hi Jeff,
I am using the optional Rotax airbox on my 912ULS. The inlets of the airbox are designed for 60 millimeters diameter SCAT, one for cold air and one for preheated air. I suppose Rotax have determined that this diameter was necessary. On my installation, cold air is suplied by a NACA on the left side of the cowl. You can see a picture of the cowl in my album http://www.europaowners.org/modules.php?set_albumName=album196&op=modload&name=gallery&file=index&include=view_album.php
I am very satisfied with this installation which allows straightforward controllable carb heat. However there is one inconvenience worth to mention: I consistently see induction air temperature (measured inside the airbox) which is 6 degrees Celsius higher than OAT. This is due to the length of SCAT ducting between the NACA intake, the filter box and the aluminum airbox, all that stuff being heated by the hot air inside the cowl. Those 6 degrees may reduce power by up to 2%. The Europa XS airbox is better on this point of view, as it takes the air directly from above and induction temperature probably equals OAT.
Regards
Remi Guerner
F-PGKL
Induction Air
Hi All,
While I have Gold Rush in for the winter annual I'm considering some
cowl changes. Including closing off the upper NACA use for induction
air on the 912-S and using the lower starboard NACA normally used for
the 914 induction. I seem to remember someone else using that for carb
intake and under cowl carb heat. I'm going to use the same air plenum
with the same filter as now but I will fabricate a side intake to
attach to the top of the plenum and a 2 inch scat tube coming up from
the below NACA. My question is this. I already have the inlet plumed
for this 2 inch tube and not a lot of room to increase it to 3 inch. My
concerns is if the 2 inch would be enough for both carbs. Has anyone
else done this with the 912-S and if so what size of tube did you use?
Best Regards,
Jeff R.
[quote][b]
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