Hi
Nothing to do with the roof but on the same subject of flow. Many people polish their heads(not only me being folloically challenged) -- cylinder type. However, you will get increased air flow if you roughen the surface slightly. Ideally you could do with a hatch marking but a very gentle wire wool rub works well. Simply put a smooth surface causes air to cling to it and causes a drag effect. On brake disks this retains heat and is why you will see holes in performance ones. By unsmoothing the surface you will gain an increase in air flow plus an increase in turbulence. Two advantages follow. You are more likely to fill the cylinder and also create more swirl enabling more efficient combustion.
Just a thought
Terry Collier
Nothing to do with the roof but on the same subject of flow. Many people polish their heads(not only me being folloically challenged) -- cylinder type. However, you will get increased air flow if you roughen the surface slightly. Ideally you could do with a hatch marking but a very gentle wire wool rub works well. Simply put a smooth surface causes air to cling to it and causes a drag effect. On brake disks this retains heat and is why you will see holes in performance ones. By unsmoothing the surface you will gain an increase in air flow plus an increase in turbulence. Two advantages follow. You are more likely to fill the cylinder and also create more swirl enabling more efficient combustion.
Just a thought
Terry Collier