Cowl openings

[TJay 1041]

Getting ready to start on my oil cooler and wondering is there a standard hole size to cut in the cowl so I don't mess with the pressure to much?

[EDMO 1078]

Getting ready to start on my oil cooler and wondering is there a standard hole size to cut in the cowl so I don't mess with the pressure to much?

Jim Chuk and Joey both had cowls for the Jab.   Maybe you can get some photos?   EDMO

Edited 16 Dec 2016 by EDMO

[1avidflyer 1983]

I found this one that might give you some ideas.  I'm not near them now to measure.  The crush plate on the outside of the prop looks like it would be the same size as the prop hub on the engine.  Just guessing, I would say the opening is about 2" high and 7" wide.  I had to make the flapper door so I could close it off in the winter to keep oil temps higher.  And I also removed the cooler in the winter as well.  JImChuk