Radiator perpendicularity to airflow, how important is it? Options

[bondo]

I'm working on radiator placement, and wondering if it's super important to mount it vertical. I know tilted radiators have bene done in 914s before, but they're usually very large radiators that wouldn't fit if standing straight up. It seems like some angle off perpendicular might improve cooling by introducing turbulence within the radiator? Too much and obviously there'd be a disadvantage. Do any manufactured watercooled cars have a tilted radiator? Seems to me I saw an RX-7 once that did. I know that the intercoooler on our WRX is pointed nearly straight up (with a scoop directing air downwards into it) and way more bugs hit the back half than the front, presumably meaning most of the air does too.

I figure that at worst I'd lose some effectiveness at cruise, because if the car is not moving, there is no airflow to be perpendicular to. Do most 914 V8s that have cooling problems have them at cruise or at idle?

[andys]

The outlet not only needs to be in a low pressure area, but also needs to be greater in area than the inlet. A rough rule is the outlet area s/b 1.7 times larger than the inlet area. Do not try to ram air into the inlet. Rely on pressure the differential between the inlet and outlet. Seal the ducting (if applicable), especially on the outlet side.

Take a look at your typical shifter kart. Though generally a poor example of managing flow (They just stick the radiator out in the airstream), they normally tip the radiator back (the top). Some years ago, they found out that their coolant temps went down when they did this.

Andys