JonJay
Well Known Member
This is a follow up on my CHT's and fixes to get them lowered. First off, they are not that bad, just could be better. (climb out 400, cruise 370 on the hottest cylinder) I decided to do one thing at a time and report on each. There are a lot of posts on this subject that where very helpful, so I am just adding to them.
The first and easiest step took ten minutes; cut off the lower cowling exit to be flush with the firewall. Did not even need to remove the cowling. I only cut off about 1".
The biggest challenge was how to compare data to see what it did. I am not a test pilot by any stretch, but I am learning a lot. My EDM930 is wonderfull at collecting the data and I am getting a handle on how to interpret.
My climb temps seemed to improve, however, my climb procedures are also better. I dont need to bust off the field at 2000fpm and sustain that, 1500fpm is fine at 140+ mph. So, not sure how much might have been affected by my poor techniques at first.
However, relative cruise temps improved, but differently for each cylinder. #1 and #2 where 30-35deg cooler for the same LOP operation, FF, HP, etc... #3 was only 10deg and #4 20deg. Still big improvements for shaving off an inch of plastic that you can't really see. Weird.
Now, off to work on #3 by opening up a gap on the back of the cylinder baffle with a washer or two. I also need to work on the cylinder baffling to ellimate some gaps that are allowing the air to leave the cooling fins before they reach the bottom of the cylinder. There is a big, maybe 1/8", gap on the lower back part of #4 about 45deg down from center.
At the same time, I am going to put an angle on #1 to block it off a little. I will fly and see where that puts me.
After that, I am going to tape off the 2" hole for the scat tube directly behind #3. That is upper plenum air being dumped directly into the lower plenum when the heat is off, or directly into the cabin when it is on. You can hear the pressure change in my Lightspeed ANR's when you open or close the heat. I will also tape off part of the oil cooler as a temporary fix as my oil temps are bit low. Maybe I can recover some air there.
And of course, continue to look for any baffle leaks out of that upper plenum. Seems pretty tight, but I will find them if they are there.
More to follow....
The first and easiest step took ten minutes; cut off the lower cowling exit to be flush with the firewall. Did not even need to remove the cowling. I only cut off about 1".
The biggest challenge was how to compare data to see what it did. I am not a test pilot by any stretch, but I am learning a lot. My EDM930 is wonderfull at collecting the data and I am getting a handle on how to interpret.
My climb temps seemed to improve, however, my climb procedures are also better. I dont need to bust off the field at 2000fpm and sustain that, 1500fpm is fine at 140+ mph. So, not sure how much might have been affected by my poor techniques at first.
However, relative cruise temps improved, but differently for each cylinder. #1 and #2 where 30-35deg cooler for the same LOP operation, FF, HP, etc... #3 was only 10deg and #4 20deg. Still big improvements for shaving off an inch of plastic that you can't really see. Weird.
Now, off to work on #3 by opening up a gap on the back of the cylinder baffle with a washer or two. I also need to work on the cylinder baffling to ellimate some gaps that are allowing the air to leave the cooling fins before they reach the bottom of the cylinder. There is a big, maybe 1/8", gap on the lower back part of #4 about 45deg down from center.
At the same time, I am going to put an angle on #1 to block it off a little. I will fly and see where that puts me.
After that, I am going to tape off the 2" hole for the scat tube directly behind #3. That is upper plenum air being dumped directly into the lower plenum when the heat is off, or directly into the cabin when it is on. You can hear the pressure change in my Lightspeed ANR's when you open or close the heat. I will also tape off part of the oil cooler as a temporary fix as my oil temps are bit low. Maybe I can recover some air there.
And of course, continue to look for any baffle leaks out of that upper plenum. Seems pretty tight, but I will find them if they are there.
More to follow....