---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Tue 08/11/09: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:31 AM - Some interesting temperatures recorded (Lynn Matteson) ________________________________ Message 1 _____________________________________ Time: 05:31:58 AM PST US From: Lynn Matteson Subject: JabiruEngine-List: Some interesting temperatures recorded Since I bought and installed the Rotec TBI-40 mechanical fuel injector on my Jabiru 2200 mechanical lifter engine, serial #2062, I've been pretty impressed with the results. Mainly the ability to adjust the mixture. For the last month, I've been making flights at various speeds and directions, and recording the EGT's and CHT's and rpm's and fuel flows with the Bing carb, and for the last week with the TBI. All the tests have been done with flights into the wind, with the wind, and perpendicular to the wind, and mostly at about 2000-3000 feet AGL. Yesterday I decided to average the results. While this is certainly not a scientific approach, it's the best I could do without having a recording device aboard, and feeding the info into a computer. Bing: EGT spread 89 deg F. CHT spread 44.4 deg F Fuel flow 4.27 gph Rotec TBI: EGT spread 84 deg F. CHT spread 21 deg F. Fuel flow 3.25 gph While these numbers may not mean much without the actual temperature numbers, it is interesting that I saw CHT's for the TBI as close as 3 degrees apart, ranging from 322 to 325. (Keep in mind that I take my readings from a thermocouple attached directly on the head, between the spark plugs, not on the spark plug location which puts the reading about a half-inch ABOVE the head, so my CHT readings will show a higher number.) Other readings of CHT's show spreads of 6, 7, 9, 10, 11, 12, 20, etc. The closest I was ever able to get the Bing CHT's was 30, 31, 34, 35, 36, etc. In thinking about why this differential in CHT's should be, between the Bing and the TBI, I can only point to the fact that the Bing has a horizontal throttle plate and shaft to which it is mounted, and the TBI has....in my installation, anyway....a vertical fuel-discharge tube, the only obstruction in the airflow at wide-open- throttle (WOT). Now the Jabiru has a vertical splitter, and maybe the vertical discharge tube and the vertical splitter make for less turbulence, and therefore more even fuel charges going into each cylinder, I don't know for sure. But the numbers are showing something to be quite different in the CHT department at least, and a less dramatic comparison in the EGT's. I'm gonna start going on longer flights today, and see how the numbers look while actually going somewhere besides around the patch. Lynn Matteson Kitfox IV Speedster, taildragger Jabiru 2200, #2062, 727.5 hrs Sensenich 62"x46" Wood prop Electroair direct-fire ignition system Rotec TBI-40 injection Status: TBI installation done...tests flights underway ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message jabiruengine-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/JabiruEngine-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/jabiruengine-list Browse Digests http://www.matronics.com/digest/jabiruengine-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.