I'm fitting the cowling around my Rotax 912is engine, the firewall forward plans call out for the NACA cut out to be 9 inches long, I remember someone saying that they had cooling problems on the ground with the 912is engine and was advised to open up the NACA cut to 11 inches which solved the problem.
Has anyone else had cooling problems with the 912is as I would rather make this enlarged cut now?