Cylinder #6 baffle modification

[outnumbered]

I see a number of folks have reported higher cylinder #6 temps. That got me wondering has anyone done a modification to the Cylinder #6 baffle that is similar to the Cylinder #5 baffle that folks have done utilizing the RV-14 baffle modification. This provides more space between the aft-most cylinder fins and the baffling to get cooling air through and avoids doing “the washer trick” that several refer to. It's a bit tight behind the #6 cylinder baffle with the round opening for the oil cooler duct but it looks doable.

 

[Kyle Boatright]

I see a number of folks have reported higher cylinder #6 temps. That got me wondering has anyone done a modification to the Cylinder #6 baffle that is similar to the Cylinder #5 baffle that folks have done utilizing the RV-14 baffle modification. This provides more space between the aft-most cylinder fins and the baffling to get cooling air through and avoids doing “the washer trick” that several refer to. It's a bit tight behind the #6 cylinder baffle with the round opening for the oil cooler duct but it looks doable.

The fin depth behind #6 is substantial. There is zero fin depth (and zero cooling airflow) behind #5. That's why you modify the baffles behind #5. The issue with #6 (IMO) is the oil cooler robbing #6 of airflow. That said, I don't see it as a major issue. While I can't endlessly climb my -10 at 100 knots and max power on a hot day, an 800 FPM sustained climb won't put any CHT's over 400.

 

[rocketman1988]

I have toyed around with this using the butterfly valve I installed in the oil cooler SCAT line. Typically, my #6 runs about 15 degrees warmer than the rest when the valve is wide open. If the oil temp is too cool, I start closing the valve to bring the oil temp up to about 190. As the valve closes, I can see definite decrease in the cht temp on #6. At altitude (~8500') in cruise, the #6 temp is basically the same as the rest and oil temp is stable around 190. Opening the valve yields the expected increase in CHT and decrease in oil temp.

As KB said, I don't think it is a major issue and my temps never really get over 400 unless I am doing a sustained slow speed climb, and then they have never gone above 410. Oil temp is easily controlled to be 190...

 

[Jesse23]

The fin depth behind #6 is substantial. There is zero fin depth (and zero cooling airflow) behind #5. That's why you modify the baffles behind #5. The issue with #6 (IMO) is the oil cooler robbing #6 of airflow. That said, I don't see it as a major issue. While I can't endlessly climb my -10 at 100 knots and max power on a hot day, an 800 FPM sustained climb won't put any CHT's over 400.

I found a 4” 60° silicone elbow and put a 4” velocity stack on the engine side to reduce flow to oil cooler and help #6. i know the stack is designed to speed up the air, but the opening is smaller than the 4” opening and tapers to a smaller dia inside the blue elbow. In addition, the velocity stack pic looks like it’s coming into the engine compartment, but it actually is going inside the blue elbow. it worked. My oil temp was fine, so robbing a little cooling here was fine. #2 & #6 are still the hottest, but the total spread is <25° on all CHT’s.

I climb out 115/120 even in FL summer, with CHT’s <385°.

 

[Kyle Boatright]

I found a 4” 60° silicone elbow and put a 4” velocity stack on the engine side to reduce flow to oil cooler and help #6. i know the stack is designed to speed up the air, but the opening is smaller than the 4” opening and tapers to a smaller dia inside the blue elbow. In addition, the velocity stack pic looks like it’s coming into the engine compartment, but it actually is going inside the blue elbow. it worked. My oil temp was fine, so robbing a little cooling here was fine. #2 & #6 are still the hottest, but the total spread is <25° on all CHT’s.

I climb out 115/120 even in FL summer, with CHT’s <385°.

Can you point me towards the silicone elbow? I have been looking for something like that.