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Baffle Air Dam Trimming

jeffmoreau

jeffmoreau

Well Known Member
I have completed approximately 20 hours of phase 1 testing on my RV-8A. The number 1 and 2 cylinders have been running about 20 degrees warmer than cylinders 3 and 4.
I have the stock Van's baffle kit installed which includes the air dam blocking device mounted in front of cylinders 1 and 2.
Can anyone give me a starting point of how much to trim away from the air dams?
I don't want to start cutting material away for fear of trimming too much.
Any information would be greatly appreciated.
 
I removed mine all together. And from the advice of Bill R. I plan to install nut plates on the horizontal angle and then will fab a news plate that I can remove and install based on OAT. Mine actually runs very well right now without any plates installed, but I suspect in the cold WI winter I will need to warm the front cylinders.
 
jeffmoreau said:
I have completed approximately 20 hours of phase 1 testing on my RV-8A. The number 1 and 2 cylinders have been running about 20 degrees warmer than cylinders 3 and 4.
I have the stock Van's baffle kit installed which includes the air dam blocking device mounted in front of cylinders 1 and 2.
Can anyone give me a starting point of how much to trim away from the air dams?
I don't want to start cutting material away for fear of trimming too much.
Any information would be greatly appreciated.
Click to expand...

I trimmed .75" off the #1 dam last week, reduced that CHT about 10F.
 
Remove the pieces and then use some aluminum duct tape (used around home furnace installations) of various widths until you get the dimension that works for your airplane. You can then cut your original parts to that width. Adding nutplates to make the part removable is a good idea but once you get it set you probably will not need to take it off. My guess would be between 1 and 1.25" on the right side and 3/4 to 1" on the left. Each plane/engine will be slightly different.
 
Mine runs fine with the original size baffles in cruise. On climbout, both #1 and #2 cylinders run hotter than #3 and #4. Since I spend more time in cruise, I've not made any modifications.

greg
 
Start small

I ended up removing just over half of the #1 baffle dam. But I did it over
several flights, removing 1/4" at a time. The #2 was ok. I only
removed the top cowling then slid a piece of aluminum sheet between
the cylinder and the baffle dam and use a cutoff wheel to trim (using
a piece of masking tape to define the cut line).

At cruise now, my CHT's are within 10 deg. In climb, #1 still runs the
warmest.
 
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