Uneven CHT Temperature Profile Stroker 340

[turbopilot]

Since my Carbon Cub arrived from the factory I have noticed a very uneven distribution of CHT temperatures in cruise. Here is a picture of my airplane in cruise.



You will note a 75F difference between #1 CHT (the coolest) and #3 CHT (the warmest). #1 cylinder is the furthest forward in the engine on the right side and with this installation has a large area of cooling fins right in the path of direct ram air. Looking to even out the temperatures (ie reduce the temperature of the warmest cylinder), used some aluminum tape to block direct airflow on #1 cylinder with the hope getting some more cool air to the back cylinders, #3 and #4.



Here is what it looks like with the foil in place.



As you can see the #3 CHT has come down by 20 degree while #1 has warmed up to a temperature comparable with the other cylinders.

Most engine installations I have seen place a baffle in front to the fins of the forward cylinders directly facing the airflow. Any reason we don't have on in the Carbon Cub?

[seastar]

Looks like we need some additional work on the baffels.
Thanks for the effort.
My airplane is supposed to be delivered at the factory on the 4th.
Probably too late to get anything done about this now.
How about a picture of your AL tape installation.
Bill

[Centmont]

Great information Bob....please keep us posted! Ralph

[rfriend]

Nice deductions and implementation Bob, I hope that there will be actions taken in the company to improve the airflow in future production due to your observations. Your work is appreciated. Future owner CC 141.

[turbopilot]

Nice deductions and implementation Bob, I hope that there will be actions taken in the company to improve the airflow in future production due to your observations. Your work is appreciated. Future owner CC 141.

Just my old home builder curiosity. In my airplane #1 is the coolest and #3 is the warmest (thus the limiting cylinder as temps climb). Looks like covering the front fins of #1 just allows cooler air to flow over #1 and help #3.

[TheCubWorks]

Hi can you take another picture of panel chts iin flight while appliying carburetor heat.
Sometimes patt of a cht sprrad is due to un even fuel distrubtion. The carburetor heat helps distribution for trouble shooting purposes.

[Centmont]

This is a pretty small sample size. How many other Carbon Cubs have EGT montoring and see the same problem? If it is consistent, then the airflow really does need some tweaking...if it is not, then this could, for some reason, be unique to Bob's aircraft. If you are a Carbon Cub owner and see the same pattern, please weigh in. R

[turbopilot]

This is a pretty small sample size. How many other Carbon Cubs have EGT montoring and see the same problem? If it is consistent, then the airflow really does need some tweaking...if it is not, then this could, for some reason, be unique to Bob's aircraft. If you are a Carbon Cub owner and see the same pattern, please weigh in. R

I think CubCrafters may be way ahead of us on this issue. Got the idea from this CubCrafter picture doing tuff testing. Note something shiny in the right cowl inlet.

[glickle]

Just a FYI during all this great tech testing by Bob et al , to add that I have just passed 200 hours on the CC 340 and running perfectly and while I do not have the glass cockpit monitoring, I can say that the cooling is sooo good that I still have about 3 inches of the oil cooler covered with the aluminum tape in 85 degree weather here in Florida to get my oil temps to run 180-200. I have also kept very accurate records of fuel and oil consumption over the 200 hours and it works out to an average of 7.3GPH fuel and .1 Qt/hr oil. Regards Gary

[seastar]

Without the Dynon panel that monitors all the cylinders no one would know the temps were uneven.
I wonder how many have been built with the capability to monitor all four?
Teething problems?
Bill