HampusA wrote:I wonder much effect their diffuser makes when it´s so high up, maybe i´m wrong but isn´t a diffuser more effective the closer you run it to the ground?
I think you're wrong but only because it's not as simple as that.
The diffuser itself is probably not height limited (indeed, the higher the diffuser the better so long as you can keep the flow attached inside because that gives a better expansion ratio) but the floor as a whole is (generally, running the floor closer to the ground is better). But if you design the whole floor as a diffuser with the 'official' diffuser then acting on that, you have a different animal to the traditional "floor close to the ground with a diffuser behind it" system.
I think the use of the exhaust, to blow the edge of the diffuser, helps to make the diffuser think its sides go closer to the ground then actually do. This will make it more effective (but probably not as effective as having the sides actually going closer to the ground if you see what I mean).
I guess that the use of (what might historically have been considered) excessive rake only works because of the extreme undercut / extended lateral floorplate that the current designs have. This effectively acts as a very large lateral skirt helping to reduce airflow under the car from the sides. Southgate used a small version of this on his Group C Jaguar and it made the underside much more effective. Perhaps the effectiveness of this is also aided by the outflow front wing endplates now used by the teams but I don't know how.
If you are more fortunate than others, build a larger table not a taller fence.