Courtesy of google translate. E&OEIs located over the injection nozzles, a very thin air filter, which in the parting plane
is held between the lower plenum and the overhead airbox. admission
the air into the airbox takes place above the driver's helmet. The cross-section area of the opening
is a compromise between the air resistance of the vehicle, and the highest
Utilization of the dynamic pressure. This pressure build-up is not negligible and leads at a
Speed of 300km / h in an increase of about 36-42 mbar (airbox efficiency)
leading to an increase in the rated power of about 35 - 40hp leads.
Anyway.
I have always maintained that the effect on a road car is negligible. I have never disputed the effect of ram air on a properly designed optimised induction system on a race car.
The air scoop above the drivers head results in almost undisturbed air entering the intake system with minimal boundary layer issues. This is a problem with side scoops as the air is already turbulent.
You also really need to have them off the bodywork clear of the boundary layer.
However the above post proves my point:
- with the optimal place to collect air
- paper thin air filter.
- a purpose designed engine intake to collect, balance and distribute air.
- high speed of near 200 mph.
and this nets... 0.5 psi over atmosphere based on those figures.
Finally (and it's nice when this happens) lets plug some f1 numbers into the previous formulae for ram air effect.
Engine displacement (l) 2.4
Rpm 19000
VE 100%
Amount of air required (l/sec) 380
(m3/sec) 0.38
Speed (mph) 200
(m/s) 89.408
Required Cross section (cm2) 42.50178955
Air Intake Diameter (cm) 20
Air Intake Cross Section (cm2) 314.1592654
Airflow at speed (m3/sec) 2.80883516
Percentage of air remaining 86.47%
Remaining Air Velocity (m/s) 77.31222433
Density of air (kg/m3) 1.2
Dynamic Pressure (pascals) 3586.308018
(PSI) 0.520150003
So using reasonable known figures for an F1 car it comes out with a little over 0.5psi which is bang on what is claimed above and validates the rs4 figures of 0.01 psi