[aerohead]

Hi Fabrio, in Hucho's book,there is a section on bellypans.Within this section is a piece on diffusers,which maximize the performance of the bellypan.I do not have the book in front of me,however,if my memory serves me,the article claims that a diffuser should have an angle of divergence of no more than 2 to 2.5 degrees,with respect to the horizontal plane or you'll be looking at separated flow.The work presumes that you have a complete bellypan ahead of the diffuser.The angles must be established with "load" in the car,so as to mimic the cars attitude,as it will demonstrate while driving with occupants and cargo.Sandbags,sacks of concrete mix,etc.,can be used to ballast the car's interior,to simulate the "load" while you set up the diffuser's angle.