---------------------------------------------------------- LycomingEngines-List Digest Archive --- Total Messages Posted Mon 11/23/09: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:23 PM - CHT update (Ralph E. Capen) 2. 06:07 PM - Re: CHT update (Deems Herring) ________________________________ Message 1 _____________________________________ Time: 03:23:47 PM PST US From: "Ralph E. Capen" Subject: LycomingEngines-List: CHT update As many of you may know, I have been obsessing a bit about my CHT's...to get them consistent. Here's the setup: IO360B1F6 9.2:1 pistons AFP Fuel Injection LASAR Ignition with CHT sender relocated to allow for testing Vetterman Dual Crossover Heater/Mufflers SamJames cowl and plenum Advanced Flight Systems 3400 Engine Monitor Oil Cooler mounted behind #4 cylinder Air for both Heater/Mufflers behind #3 cylinder For constant power setting, here's the consistency that I have achieved: #1 and #3 cylinders run within three degrees (avg) of each other #2 and #4 cylinders run within three degrees (avg) of each other The #1/#3 cylinders run 8.5 degrees hotter (avg) than the #2/#4 cylinders With the members of the sets of cylinders running this close each other, I'm thinking that I have the balance (front to rear) for each side pretty well matched. I'm trying to wrap my head around what could be causing the right side to run hotter than the left. Here's some of what I'm thinking...: With this plenum set-up, I'm thinking that the pressure/volume should equalize from left to right. This would leave me with not much to change to cause more cooling air to go from the left to the right - meaning that I probably have to live with the differences. Alternatively, maybe it's not really hotter...the two sets of CHT wires for the left side (both equal length) are about three feet longer than the ones for the right side (again, both equal length). Could the difference in the lengths of the wires account for the reported temperature difference? I'm pretty close to thinking that this is as good as it gets...but I would really like to know why... Thanks, Ralph ________________________________ Message 2 _____________________________________ Time: 06:07:05 PM PST US From: Deems Herring Subject: RE: LycomingEngines-List: CHT update The accuracy of the readings is a different question but the relative flow on each side should be controlled by the length of the baffle below and bet ween the cylinders. increase the length of the baffle for the cold cylinder s or or shorten the ones for the hot cylinders to change the balance. Remov e the same amount from both ends of baffle if you don't want to change the balance between 1/3 or 2/4. I wouldn't have a pm with calling what you have close enough. Deems Here's the setup: IO360B1F6 9.2:1 pistons AFP Fuel Injection LASAR Ignition with CHT sender relocated to allow for testing Vetterman Dual Crossover Heater/Mufflers SamJames cowl and plenum Advanced Flight Systems 3400 Engine Monitor Oil Cooler mounted behind #4 cylinder Air for both Heater/Mufflers behind #3 cylinder For constant power setting=2C here's the consistency that I have achieved: #1 and #3 cylinders run within three degrees (avg) of each other #2 and #4 cylinders run within three degrees (avg) of each other The #1/#3 cylinders run 8.5 degrees hotter (avg) than the #2/#4 cylinders With the members of the sets of cylinders running this close each other=2C I'm thinking that I have the balance (front to rear) for each side pretty w ell matched. I'm trying to wrap my head around what could be causing the right side to r un hotter than the left. Here's some of what I'm thinking...: With this pl enum set-up=2C I'm thinking that the pressure/volume should equalize from l eft to right. This would leave me with not much to change to cause more co oling air to go from the left to the right - meaning that I probably have t o live with the differences. Alternatively=2C maybe it's not really hotter ...the two sets of CHT wires for the left side (both equal length) are abou t three feet longer than the ones for the right side (again=2C both equal l ength). Could the difference in the lengths of the wires account for the r eported temperature difference? I'm pretty close to thinking that this is as good as it gets...but I would really like to know why... Thanks=2C Ralph _________________________________________________________________ Windows 7: It works the way you want. 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