---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Tue 09/30/08: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:29 PM - Re: Kitfox-List: CHT probe placement (Lynn Matteson) 2. 10:02 PM - Re: CHT probe placement (Jim Crowder) ________________________________ Message 1 _____________________________________ Time: 03:29:59 PM PST US From: Lynn Matteson Subject: JabiruEngine-List: Re: Kitfox-List: CHT probe placement I did some tests today regarding the CHT probe placements on my Jabiru 2200 engine. I'm cross-posting this so others can benefit, and even make assumptions regarding other engines, perhaps. I was wondering out loud about how the different mounting locations for the thermocouple probes might affect the readings of the cylinder head temps. During my recent overhaul, I decided I didn't like the "under- the-spark-plug" mounting location, so I changed to a location that required me to drill into the head, tap it for an 8-32 machine screw...actually a socket head cap screw...and affix the proper electrical terminal onto the end of the t'couple probe...after removing the spark plug terminal of course. First I went up and got some CHT numbers as the basis for comparison. I noted that cyl. #1 ran 317, 327, and 340 F, during various phases of flight. Noting these, I then took the probe from cyl #3 and attached to it a spark plug terminal (12mm), and installed it onto the spark plug that lives over the exhaust valve on #1 cylinder. I first removed the spark plug washer like Jabiru says to do, installed the probe/terminal, then reinstalled the spark plug washer, and reinstalled the plug. Then went flying again. Here is how I'll report the numbers....I'll call the new location (the machine screw termination) CHT, and the spark plug termination, SP, as In (CHT/SP) The numbers I got were as follows (with an ambient of 61 F) (drum roll please)....initial taxiing= (250/220); taxiing further= (266/230); climbing out= (308/232); further climbing=(321/243); leveling off (not recorded for how long level)= (330/245); not noted what attitude, but not climbing=(334/249); climbing again briefly= (344/248) I noted that the max differential was 96 F, and the climbing EGT's were in the high 1200's. I didn't have enough hands, instruments or inclination to record every aspect of the test, but I got enough to satisfy myself that my new locations for the CHT probes work, and now I can rest assured that I'm not overheating the engine as I thought I might when I first started it up with this configuration. Needless to say, the CHT's now apparently rise more quickly, and if you're like me, and you've been accustomed to seeing it rise slowly and only into the low to mid- 200's, the ol' pucker factor rises just as quickly and the finger gets close to the panic button, but it's just numbers, and now that I've done some testing, I'll relax a bit on this subject at least. Lynn Matteson Kitfox IV Speedster Jabiru 2200, 562 hrs, and counting...all systems are go, or nearly so... ________________________________ Message 2 _____________________________________ Time: 10:02:53 PM PST US From: "Jim Crowder" Subject: RE: JabiruEngine-List: CHT probe placement Lynn, I have decided to use the factory holes on my 3300 and surface mount the sensors using the 8-32 machine screws. Did you use steel, stainless steel, or aluminum screws? I am thinking maybe aluminum if I can find them. I can guess what the issues might be. Jim Crowder ------------------------------------------------------------------------------------- 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.