Today's Message Index:
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1. 03:47 PM - FYI on airbox's (Roger Lee)
2. 04:02 PM - Re: FYI on airbox's (Craig Payne)
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This is a copy of a post from the www.ctflier.com website. It is a good FYI about airboxes. Jeremy is a good friend and very knowledgeable, plus he has been to the Rotax factory to get qualified for "Overhaul" on the Rotax.
Jeremy@CPS
Advanced Member
Group:Members
Posts:10
Joined:19-June 10
LocationTracy CA
Posted Today, 02:16 PM
Only about 10% of the slsa mfgs use the tuned aurbox and even fewer of the experimental's
even mention it in there construction Manual. The idea is to stabilize
the airflow between booth carbs by first running all intake air into a single
filter and then ensuring that both carbs are having identical airpressure
entering the venturi. This set up translates to a smoother running engine and
thus in turn increases power very slightly. The other added advantage is the ports
for the floatbowl vent lines. This ensures even pressure on the fuel in the
bowls and allows for more even EGTs. These are two features that FD attempted
to copy on the early SWs and there system works well enough.
Exhaust however is more critical. The power an engine can produce is heavily dependant
on the amonut of back pressure the exhaust imposes on the cylinder. Too
much pressure and the engine will choke down and lose power. Not enough pressure
(which is the case in most twin exh. Setups) and you risk burning exh valves
becuase the fuel is still burning as it leave the combustion chamber rather
than burning completely inside.
The same principle with smooth running applies to the intake are along with the
exhaust air exiting. (equal pressures= smoother operation and less oposition
the engine had to throttle response.)
A&P
FCCL
Sport Pilot
ROTAX MECHANIC -912 OVERHAUL RATED
Technical Director & Rotax Warranty Rep. for California Power Systems
Nor-Cal Emergency Field Services, LLC -Owner
(209)481-5881 Cell
(510)247-9653 CPS Shop Mon-Fri
Nor_Calefs@Yahoo.com
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322783#322783
Message 2
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The other (theoretical) advantage to an airbox (when compared to the usual
pair of filters drawing warmer air from inside the cowl) it that you are
drawing outside, cool air which translates to more power. How much is an
open question. In conventional engines applying carb heat causes a drop in
power. But I doubt the under cowl air is as hot as air drawn from a shroud
around the muffler.
-- Craig
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Roger Lee
Sent: Thursday, December 09, 2010 3:44 PM
Subject: RotaxEngines-List: FYI on airbox's
This is a copy of a post from the www.ctflier.com website. It is a good FYI
about airboxes. Jeremy is a good friend and very knowledgeable, plus he has
been to the Rotax factory to get qualified for "Overhaul" on the Rotax.
Jeremy@CPS
Advanced Member
Group:Members
Posts:10
Joined:19-June 10
LocationTracy CA
Posted Today, 02:16 PM
Only about 10% of the slsa mfgs use the tuned aurbox and even fewer of the
experimental's even mention it in there construction Manual. The idea is to
stabilize the airflow between booth carbs by first running all intake air
into a single filter and then ensuring that both carbs are having identical
airpressure entering the venturi. This set up translates to a smoother
running engine and thus in turn increases power very slightly. The other
added advantage is the ports for the floatbowl vent lines. This ensures even
pressure on the fuel in the bowls and allows for more even EGTs. These are
two features that FD attempted to copy on the early SWs and there system
works well enough.
Exhaust however is more critical. The power an engine can produce is heavily
dependant on the amonut of back pressure the exhaust imposes on the
cylinder. Too much pressure and the engine will choke down and lose power.
Not enough pressure (which is the case in most twin exh. Setups) and you
risk burning exh valves becuase the fuel is still burning as it leave the
combustion chamber rather than burning completely inside.
The same principle with smooth running applies to the intake are along with
the exhaust air exiting. (equal pressures= smoother operation and less
oposition the engine had to throttle response.)
A&P
FCCL
Sport Pilot
ROTAX MECHANIC -912 OVERHAUL RATED
Technical Director & Rotax Warranty Rep. for California Power Systems
Nor-Cal Emergency Field Services, LLC -Owner
(209)481-5881 Cell
(510)247-9653 CPS Shop Mon-Fri
Nor_Calefs@Yahoo.com
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322783#322783
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