---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Sat 08/17/13: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:28 PM - Re: Jabiru 3300 CHT Disparity (BobP) 2. 07:16 PM - Re: Re: Jabiru 3300 CHT Disparity (FLYaDIVE) ________________________________ Message 1 _____________________________________ Time: 02:28:22 PM PST US Subject: JabiruEngine-List: Re: Jabiru 3300 CHT Disparity From: "BobP" I don't see how a CHT thermostat properly mounted in a small hole between the plugs can do anything but record the true CHT temperature. I can see how a thermostat crimped into an aluminium tag that is waving in the breeze might not accurately display the temperature at the other end of the tag (ie at the plug/head interface). If the air blasting over this tab were to be increased (eg by fitting a baffle that deflects and concentrates air onto the sensor tag) I would expect the thermocouple temperature would reduce - even if the baffle restricted the total airflow over the head so far that true head temperature increased. If the above is true it would explain why the readings of sensors in the two different positions give differing readings. BobP PS is there a text summary of the presentation that started this thread? -------- BobP Read this topic online here: http://forums.matronics.com/viewtopic.php?p=406929#406929 ________________________________ Message 2 _____________________________________ Time: 07:16:14 PM PST US Subject: Re: JabiruEngine-List: Re: Jabiru 3300 CHT Disparity From: FLYaDIVE Bob: Anything that changes the conductivity of heat between the spark plug and the engine/cylinder will effect the CHT. A spark plug is designated as a 'cold' or 'hot' plug because of the amount of heat it holds. The LESS heat that is conducted off the plug makes the plug a hotter plug. A hotter plug will cause the CHT's to increase. Putting s Ring thermocouple under the spark plug cause LESS heat to be conducted away from the plug which raises the heat range of the plug and therefore the CHT's. Also - Ring thermocouples read HIGHER because the heat range of the plug is now increased. I am not sure of what you are saying about a crimped aluminum tag? Would you have a part number that can be researched online with a picture? Barry On Sat, Aug 17, 2013 at 5:27 PM, BobP wrote: > > I don't see how a CHT thermostat properly mounted in a small hole between > the plugs can do anything but record the true CHT temperature. > > I can see how a thermostat crimped into an aluminium tag that is waving in > the breeze might not accurately display the temperature at the other end > of the tag (ie at the plug/head interface). > If the air blasting over this tab were to be increased (eg by fitting a > baffle that deflects and concentrates air onto the sensor tag) I would > expect the thermocouple temperature would reduce - even if the baffle > restricted the total airflow over the head so far that true head > temperature increased. > > If the above is true it would explain why the readings of sensors in the > two different positions give differing readings. > > > BobP > > PS is there a text summary of the presentation that started this thread? > > -------- > BobP > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=406929#406929 > > ------------------------------------------------------------------------------------- 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.