ACourtney wrote:Hi Justin,
There is usually some positive pressure under the car, unless you seal the underside of the engine bay with an undertray and duct all the hot air out of the top and sides of the bonnet.
The other area of high pressure is in the wheel arches. Firstly, wheels create positive pressure by having to push aside the air that is in front of them. Then the wheels act like rotary pumps and create positive pressure by dragging air up into the arches. This effect will be more noticeable at the rear where the tyres run closer to the inside of the wheel arch. I suspect that you haven't completely re-sealed the boot after installing your rear springs mounts, so the positive pressure in the boot will be more likely than in a standard Cortez.
To get some fresh air flowing through the car you need to take it from an area of positive pressure, such as right in front of the car, or at the base of the windscreen. In the original design Richard Oakes tried to use the bonnet stiffener to duct air from just in front of the radiator to the heater intake. In principle this is a good idea, but in practice I haven't come across a Cortez, or Excelsior that hasn't had a hole, or slot, cut out of the stiffener at some point to clear something under the bonnet. It is also possible to take cold air from the front wheels arches, but remember that the brake pad dust gets spread around this area so it isn't air that you would want to breathe in.
Thanks Alistair.
My bonnet is ducted as you describe but I have cut into one of the ducts to fit my bonnet vents - they were sited for style not function as such.
Anyway getting air in isn't a problem the fan blows and sucks well.
Windows down either stationary or moving the windows are clear and a good blast from the vents on the dash.
Windows up and the air doesn't escape thus causing no airflow and misty windows. .
The boot floor is now sealed but as I've isolated it from the interior compartment it's irrelevant.
I guess that windows down on the move causes a negative pressure as the air passes the outside of the car as aids the exit of ducted air through the dashboard.
I just need to replicate the effect with the windows up