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?

[lapuwali]

With appropriate ducting, the angle to the airflow isn't important. What's important is to have higher air pressure on one side of the rad than the other. You could have the rad be completely parallel to the airflow into the inlet duct, so long as you had the outlet side ducted to somewhere with lower pressure. This also means completely ducting the rad so air on one side has to go through the rad rather than around it.

Paying attention to the rad outlet can pay significant dividends in getting good airflow through the rad. If you can duct the outlet to a low pressure area, you'll get much better airflow than if you simply had it dump into the trunk. The commonly seen hole in the floor of the trunk will cause the air pressure in the trunk itself to fall some as the car moves, due to airflow under the car past that hole. A similar arrangement with a hole in the lid, with a flip-up at the leading edge of the hole, will also cause a low-pressure area. If you then seal the rad to the trunk walls so air comes in under or through the front bumper, and can only go through the rad to get to the trunk, you'll get good flow through the rad, even if you laid the rad completely flat.