---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Thu 12/09/10: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:47 PM - FYI on airbox's (Roger Lee) 2. 04:02 PM - Re: FYI on airbox's (Craig Payne) ________________________________ Message 1 _____________________________________ Time: 03:47:01 PM PST US Subject: RotaxEngines-List: FYI on airbox's From: "Roger Lee" 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 _____________________________________ Time: 04:02:22 PM PST US From: "Craig Payne" Subject: RE: RotaxEngines-List: FYI on airbox's 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 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.