Exhaust Idea

[Jersey Tom]

The downforce created by facing them up would be mimimal at best.

Top fuel cars generate ~800lb of downforce from exhaust pointing up. It's not completely trivial.

The stability of the car is true but who cares on it.
The cars are designet to be fastest on one hot lap and the driver
simply has to get used to the cars handling.

Are you nuts? No. It doesn't work like that. Stability and balance are CRUCIAL to making a fast car.

[AeroGT3]

Don't you think its a bad idea to LOSE a lot of grip when the driver lifts/brakes?

[Belatti]

The downforce created by facing them up would be mimimal at best.

Top fuel cars generate ~800lb of downforce from exhaust pointing up. It's not completely trivial.

WOW, I knew by intuition that it was big but didn´t know how much!
Thanks!

[flynfrog]

Don't you think its a bad idea to LOSE a lot of grip when the driver lifts/brakes?

no peak Hp and peak DF are all that matter

[Birel186]

But they moved the exhaust on top of the car wile they still
had the bigger diffusors, so the reason can't be the change in the rules.
I still wonder what effect it exactly makes to let them point up.
The effect must be better than leting point them into the diffusor.

I think they have the exhaust coming from the top so the heat helps with downforce on the rear wing.

[Ciro Pabón]

I agree with Birel: I think the exhaust position depends on its inffluence on rear wing and, maybe diffussor. Heated air produces less downforce, so it cannot be that simple.

What a nice avatar, Birel! Way to go.

[ginsu]

I think they have the exhaust coming from the top so the heat helps with downforce on the rear wing.

Exactly, the exhaust gas velocity works to entrain the flow through the 'tunnel' between the bottom of the rear wing and the top of the mid wing. This will increase the velocity through this area of the car and should help pull air out from under the car, effectively making the diffuser generate more downforce. In essence, it works the same way as putting the exhaust on the bottom of the car, but I think the main difference is that it does not make the diffuser as sensitive to engine RPM and thus you maintain better stability because the aerodynamic center of pressure is not fluctuating as wildly front to rear.

[connollyg]

I am pretty certain that at the time that exhausts migrated from under the diffuser to above the reason given was to do with stability and balance. As was said previously in this thread, getting off the throttle would give less downforce at the rear and cause balance problems.