The other thing worth consideration, is the longer (within reason) and
smoother the transition from plenum to carb throat the better
the perfomance, this allows the air to continue accelerating with
minimal turbulence, giving the best possible atomisation of the fuel
into the airflow. Hence the reason for the velocity stacks (trumpets)
seen on a lot of natually aspirated race engine.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of GRAHAM
SINGLETON
Sent: Tuesday, June 08, 2010 9:29 AM
To: europa-list@matronics.com
Subject: Re: Europa-List: Combustion air inlets
Don't think it matters Ram or not Ram, what's important is that the
float chamber sees the same pressure as the inlet throat. It is
important the the airflow is same velocity across the diameter.
Variation will upset the mixture and smooth elbows into the carb will
give varying velocity. Best if the air goes in straight from the plenum
not elbowed.
Graham
-------------------------------------------------------------------------
-----
From: Gary Leinberger <Gary.Leinberger@millersville.edu>
To: "europa-list@matronics.com" <europa-list@matronics.com>
Sent: Monday, 7 June, 2010 19:56:00
Subject: RE: Europa-List: Combustion air inlets
<Gary.Leinberger@millersville.edu>
My understanding is that the Bing carbs on the 912S are not designed
for ram air - on my Europa I am using the 914 FWD kit on a 912S (I
originally planned on a 914 but the price differences of recent years
seems excessive). This has the advantage of not taking in water during
rain or when on the tarmac. The air box around the NACA inlet is sealed
mainly so that only cool air enters the carbs - but the air filter box
is vented to the carbs so that there is no excess pressure in the air
going to the carbs. The 914 is boosted, but requires numerous other
gadgets to allow the Bing carbs to function properly with the excessive
pressure.
Gary Leinberger
A237
Lancaster, Pa.
95% done, 95% to go.
________________________________________
From: owner-europa-list-server@matronics.com
[owner-europa-list-server@matronics.com] On Behalf Of Fred Klein
[fklein@orcasonline.com]
Sent: Sunday, June 06, 2010 7:41 PM
To: europa-list@matronics.com
Subject: Europa-List: Combustion air inlets
On Jun 6, 2010, at 12:38 PM, Frans Veldman wrote:
While solving my cooling problems, I learned a few things:
1) Naca ducts provide no ram air, but merely "allow air to get in".
To all you 912S powered flyers,
Page 8-1 of the Europa "912 Rotax installation manual" states:
The engine inlet air is fed through a NACA duct situated in the top
cowling. It passes into a plenum
chamber which feeds the air directly to the carburettors. This ensures
that the coolest air available is
used at all times, thus ensuring no reduction of engine performance.
If Frans is correct, it would appear to follow that the 912S plenum
does not offer inlet air to the carbs under ram air pressure.
And since the 914 engine inlet is a NACA vent also, the same would
apply.
I'm surprised...having thought that engine performance benefits when
the carb gulps air which is above ambient pressure.
Any wisdom to pass on to a heretic?
Fred
A194 (w/ ics.com/Navigator?Europa-List"
target="_blank">http://www.matronics.com/N= - MATRONICS
WEB FORUMS= -->
|