But once you put the engine in the back, there are all manner of advantages. You can get rid of the driveshaft (weight) lower the hood (visibility) and be more creative with shape (aero). For Porsche it was all about reducing drag. The original even had covered wheels.
http://buildraceparty.com/wp-content/uploads/2014/06/Porsche...
Are they "willing to run at a higher temperature?" I feel you're begging the question, but I'd be delighted to be shown I'm wrong. The engine has cooling requirements, and they're met by careful ducting and a fan that the engine runs directly, or indirectly.
VW Beetles and early buses ran a fan off a generator or alternator via a belt from the engine, and VW type 3 and 4 engines (and at least later, if not all air-cooled Porsche 911s, (and 912s?)) are run off the engine crank. The engine needs to be cooled, needs airflow (ask a knowledgeable BMW airhead motorcycle owner). So, "why not put then engine up front" could be answered with "we've contained all cooling requirements in the engine itself, so we put it where we want."
As I read more about this there are lots of interesting considerations[0]
but I don't see "willing to run at a higher temperature" as a consideration, yet.
[0] "Internal combustion engine cooling" on @Wikipedia: https://en.wikipedia.org/wiki/Internal_combustion_engine_coo...
Edit: s/chilling/cooling/
There are a couple different temperatures to speak of. There is the overall engine temp, which may well be very similar to a modern engine. But there is also the temperature of the cylinder walls deep inside. An air-cooled engine relies on metal to conduct heat away from the heart of the engine. A water-cooled engine puts a pipe of cold water right alongside the cylinders to physically move heat away. So the internals of an air-cooled engine go through a much wider temperature range during normal operation. With differential metals that means gaps... gaps between the cylinder wall and the piston. That in turn means increased wear and emission-related problems. An air-cooled engine is willing to suffer these issues for the advantage of decreased weight and complexity. An air-cooled engine not willing to suffer this internal heating would be a very slow and heavy engine.
Having a hotter cylinder wall can also impact choice of fuels (need higher octane) and compression ratios (need less) as the hot walls might ignite things before the spark.
See: http://www.pelicanparts.com/techarticles/911_carrera_oil_coo...
In 1969 on the 911S, a front mounted radiator-style cooler
was mounted as standard equipment in the front right fender
well. In 1973, the newer trombone, serpentine, loop or
cooling pipe cooler as it was called, replaced the radiator
style cooler. This style of oil cooler was used through 1983.
And now that I check wikipedia, I learn that the Beetle also had an oil cooler! My god, I've been living a lie.
The 911 has two oil coolers (well, from the mid '70s, anyway) - one in the right front fender, and one mounted to the engine itself.
Many water-cooled cars do have an oil cooler, but it's not the primary means of cooling the engine. In those cases it's more about keeping the oil at a constant temperature.
Oil cooled cars have sump capacities 2x water cooled cars.