A&Q about 350Z
Q:
what a way to admit that you're wrong
A:
I'm sorry, you must not be reading right, nobody ever said anything about being wrong.
A:
thanks
A:
You clearly don't know much about many super cars.
The Norm is to slope them backwards.
A:
I'm probably wrong and willing to accept it but first could you explain this?
the only supercar that has it sloping backward is the Saleen S7
Also how come nearly every single prototype racer had it sloping forward when the radiator was front mounted? Take for example the Ferrari 333SP, Sauber C9, XJR-9LM,etc
A:
It mostly depends on the airflow over/through the front of the car, as well as the packaging requirements. The S7 might have it sloped backward because of the internal layout of the chassis members, and other parts. However, mechanical layouts in cars aren't always 100% function...sometimes they are necessity based on aerodynamic packaging requirements and aesthetic requirements. The most efficient layout is to have the airflow directly perpendicular to the radiatior. In the McLaren F1, for instance, both road and race versions have dual, vertically-oriented radiators.
A:
thats true. The F1's radiators are on the sides infront of the rear wheels right?
A:
The two scoops on either side of the front end feed the radiators, which are located in front of the front wheels. Race derived versions of the F1 also have supplementary oil/transmission coolers located low on the body, just in front of one of the rear wheels.
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o, thats why the LM and GTR have the opening on the side.
A:
If we take a look at the basic principles, what makes air flow? Pressure of course. So in order to have a flow through the radiator the pressure after the radiator must be lower than in front of the radiator.
If we take a look at some racecars we can find that their cooling inlets and outlets are placed in such a way that they take advantage of low and high pressure zones created when the car is moving. These pressure zones are dependant on the velocity of the air, air moving faster results in lower pressures. For example air moving around the front corners of the car results in a low pressure. Other low pressure zones are behind the front wheels, over the engine cover of a mid engine car, at the front of the hood of a fron engine car. Take a look at for example Saleen S7 and you know why it has the air oulets at the fron corners of the car. Now you also know why the F40 has air outlets throgh the rear window over the engine, and why Mitsubishi and Subaru WRC cars has cooling exits at the front of their hoods.
A typical high pressure zone is at the front close to the centre of the car close to the ground. If we add a front splitter to the car this will do nothing for the cooling, but what it will do is that we use this high pressure zone to create downforce. The pressure above the splitter is much higher than under hence a force directed downwards will be created.
In a high pressure zone we place our air intakes in order to get maximum pressure difference over the radiator.
Now, perhaps you are wondering why the radiators in a racing car is slanted? Well, it has been found that a very high air flow velocity through the radiator isn't going to do much for the cooling, while it will increase drag. A slanted radiator also means that we can fit a much larger radiator for a given frontal area, hence increase cooling capacity without increasing drag. In a F1 car the flow through the radiator is done at about one third of the intake air velocity.
With racing cars they are also trying to use the highest coolant temperatures possible. This is done since a greater temperature difference will result in a higher energy transfer, we can in other words remove an equal amount of heat without increaseing airflow and this means reduced drag.
Air entering the radiator is cooler than air exiting. For a given area this indicate that the exhaust velocity is greater than the intake velocity since exhaust volume is greater due to the increase in temperature. This also indicate that it should be possible to create thrust with the flow through the radiator. With the friction losses that occur in the radiator this have however shown to be difficult to achieve.
Since air exiting the radiator is hotter than the air in that air will also be less dense. This means that in order to create maximum downforce this air should no be allowed to later pass the wings. A F1 car can for example have chimneys that directs the hot air away from the rear wings.
Air should also not be allowed to pass under the car or be directed downwards as that would result in lift.
F1 cooling layout
Cooling air exit of a Renault F1 car, the so called "chimney"
As for the Ferrari F40 I'm not sure about the layout of its cooling system but if the radiator is placed in the front of the car the air might go through the radiator and then out in the front wheelhouses for example. The LM version did use a hole in the hood like the F50 which can be seen on the picture of the F40 LM model below.
Bentley Speed 8 has the radiators at the middle of the car instead
A:
The air passing through the radiator on a non-LM F40 probably goes round the luggage compartment (see how it's shaped) and exits in the huge opennings in front of the doors as well as the wheel wells.
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Thank you ales for figuring out the F40 thing. I never noticed the shape of the luggage compartment would direct the hot radiator air around it and though the openings behind the front wheels. Thank you SaabJohan, for that amazing write up... now I know what those "chimneys" on F1 cars are used for
A:
in an open wheeled racecar, shouldn't they direct the hot radiator air over the wheels because it's less dense and wouldn't create as much drag? the wheels on an open wheeled racer create alot of drag, that's why they already have wings to throw air around them