This is an evolving story, I will update the post as more info becomes available
It has been reported in Pitpass.com that exhaust blown diffusers will be effectively banned in 2012. Currently exhaust outlet can be anywhere on the car, many teams aim the exhausts at parts of the diffuser to create greater downforce. Red Bull for example blow theirs under a 5cm opening in the floor, Renault blow theirs at the floors leading edge and Ferrari\McLaren and many other teams blow theirs over the top of the diffuser.
Along with the hot overrun engine mappings, teams have been exploiting the exhaust gasses for aerodynamic gain. Something the FIA have been increasingly uncomfortable with.
According to the BBC “From 2012, pipes will have to extend to between 330-350mm beyond the rear wheel centre line, will have to be in a space between the lower rear wing and top of the diffuser and will need to be circular in dimensions, with a vertical cut-off”. This is effectively at the trailing edge of the rear tyres. Although some careful placement might find a tiny aero gain, the massive benefit of the EBDs will be lost.
Following the Technical Working Group meeting this week, Autosport reports that the ban on blown ovverrun engine maps will go ahead from Silverstone, but a compromise on the location of 2012 exhausts has been reached. Teams wil now be mandated to use periscope style exhausts as were the norm from 1998 until this year when low placed exhausts became the universal fitment. It remains to be seen how the rules will enforce exhausts in this location.
With the initial ban on how overrun engine mappings, Renault and red Bull stand to lose out the most. With the full EBD ban in 2012, it is again these teams with the most to lose as each of these teams blow beneath the floor. Teams such as Ferrari and McLaren who have committed to aggressive blowing the diffuser will also stand to lose from the ban.
Engine suppliers will have to work on ways to make the engines work with such long secondary exhaust pipes, teams will have to work out the packaging of the exhaust, blowing most likely near the cars centre line, which brings the exhausts close the hydraulics and gearbox. In this area blowing the underside of the beam wing could be exploited, or blowing the gurney at the diffusers trailing edge will also be an attractive option. Blowing outboard is unlikey to be attractive, as it create the longest exhaust routing and exposes a lot of floor to the heat radiating from the exhaust pipe. In both case the longer exhausts will obstruct airflow to the diffuser, forcing some compromises in packaging.
One benefit for fans will be the clear line of sight to the exhausts, allowing us once more to the flames on the overrun and when revving on the grid before the start.