F430 challenge grill air blockage

For whatever its worth, my 430 Challenge race car didn't come with anything blocking the grill... Lots of heat escapes from there when I come off the track.

 

you mean much like a golfball having dimples. i guess commonsense is relative to what it is you are discussing. are we talking about aerodynamics or cooling? i guess either or, it still makes sense to have it removed (the grill cover). please dont take this the wrong way as im not try to start anything, i know how people get real sensitive on the net. this doesn't even seem debateable.

 

+1, That confirms my observation as well.
No plates for both 430 Challenge and 430 Scuderia, and both generate substantially more heat than the F430 street car.

 

Here are some pictures on the 430 Challenge cars...
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+1....as I said before my 2007 F430 with the rear carbon fiber challenge grille does not have those plates.

 

No, you're confused here - the radiator situation and the air cooling sutuation are different - you're actually contradicting yourself here. I don't know exactly what the plates are for, but it's not merely to retard airflow for the sake of the air "absorbing" more heat.

 

2 more observations:
1) Challenge Stradale has better heat dissipating results than 360 Modena
2) Spy shots of 430Scuderia are missing the plates
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+2... I just took delivery yesterday and I do not have those plates either. How they would enhance cooling is beyond me. I would take them off.

 

+3 I dont have them on my F430 with challenge grill

Bart

 

Are you trying to suggest that how long a gas or liquid remains in contact with a hot surface (as it flows by) has no material impact on thermal conductivity or the heat transfer that occurs between the molecules?

Try running your hand past a hot burner on your stove real slow, then do it real fast and tell me which transfers more heat to your hand. If you are trying to cool a hot object, you want to ensure maximum heat transfer by conduction.

I don't know what the plates are for either, or if they have anything to do with heat transfer; maybe they are just there for looks However, I do believe that the velocity of air flow over the engine (or the flow of water through a radiator, etc.) all can have a major impact on the heat transfer that takes place between the respective molecules as they pass by one another.

Ray

 

No, that's radiant heat transfer, and is not relevant to engine cooling (at least in the context of this discussion). Also, the vents in the back of a Ferrari allow extra heat transfer away from the engine by means of convection, not conduction. These are fundamentally different modes of heat transfer.

Tell me this: Do you think putting your hand over the burner cools the burner (which you're implying is like a hot engine?) Not really. If you want to cool the burner, you can try moving air over it, and the faster you move the air, the more heat will be removed from the burner, and the cooler it will get.

 

Heat transfer occurs usually as a combination of one or more, not any single mode. If you are talking about the hot air moving, that's convection. If you are talking about the air heating up due to being in contact with the surface of the hot engine in the first place, that's largely conduction between the metal and air molecules. I'm sure due to the heat of the engine, some level of radiant heat is involved also. For example, if the headers start to glow red, that's clearly radiation [i.e. radiant heat] in the form of light that the human eye can see.

The question is whether the velocity of the air is a factor in cooling. Look at it from this standpoint: say you take X volume of air and put it into the engine compartment for a second, then quickly remove the air. That volume of air would be cooler than if you allow the same air to stay in the engine compartment longer - say 10 seconds. If that's true, then the temperature of the air has increased more by virtue of being near the hot engine longer. As such, if the air is hotter, then more heat from the engine has been conducted into the air molecules. That can only serve to cool the engine better, once that volume of hot air is removed from the engine compartment.

In the case of the motor, I agree moving more air over the engine would probably serve to cool it better - given an unlimited supply of cool air. The only point at which all this would not be true is when the friction of the air molecules against the engine became so great that it resulted in heat being added to the engine (due to friction), rather than being taken away (an example of this is when the space shuttle comes back into the atmosphere; the friction of the air molecules against the heat shield heats up the material on re-entry). In that case, having air rushing against the surface actually produces heat, instead of taking it away. Of course, since the air isn't rushing over the engine at 1000+ MPH, it's not a factor here

So the question still remains: why is Ferrari blocking air flow out of the engine compartment? It seems odd that it's only on that one car.

Ray

 

Ray, I think you need to review your "Fundamentals of Heat and Mass Transfer" textbook.

 

Don't be flip. If there is something in the post above that is not true, then let's hear specifics. As far as I know, the above run down is very valid when it comes to how heat transfers from a hot object to a cooler object. If I'm off base some place, then let me know.

I agree that - in general - more air over the engine will cool it better. However, in some cases, air flow issues (turbulence, velocity, etc.) can also cause problems (hot spots, etc). My original post was suggesting that perhaps this is why there is something limiting air flow back there.

Ray

 

This thread seems to be getting hot already, let's cool it guys.
There are no 'plates' in the 430Scuderia and the FXX, so it could be a new update that recent 430s do not receive them.
Have fun!
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You are correct that in the case of a hot engine in relatively cool moving air, heat is transferred through more than one mode, but by far the primary mode is forced convection, probably 90-95%. In terms of the air molecules heated by conduction, this is only at distance y=0 form the engine surface, and is the initial part of the thermal boundary layer. This is a component of convection.

"Hot air moving" is not convection - convection is the mode of heat transfer between a surface and a fluid in motion.

Regarding your second paragraph, and your other posts on the subject, that's just not how it works. In fact it's just the opposite. We're not trying to HEAT air, we're trying to COOL engine. In your example, the engine would retain more heat if you take the X air and leave it there longer - the engine would not be cooler. Generally speaking, increasing the heat flux ( rate of heat transfer per unit area ) from the engine can be accomplished by increasing the moving volume of cooling fluid (air) per unit time, NOT decreasing it.

A large temperature differential between surface and fluid results in greater heat flux between surface and fluid. So, if you trap fluid near surface and reduce temperature differential (by heating air), you'll see less heat flux than if you constantly replace the fluid with cool fluid that has a high temperature differential relative to the surface.

You propose the opposite, and that is wrong.

 

Thank you for the run down. That seems to make more sense all right, now that I hear it.

Ray

 

I might add that automobile engines are Heat Engines and produce far less power than theoretically possible because of thermal inefficiency. "Cooling" and engine is not necessarily desirable, as it tends to reduce the thermal efficiency of the engine by removing more of the energy produced by the fuel burn. We like to "cool" engines to preserve the materials used to build the engines, and the components surrounding the engine like wiring, hoses, and pretty Rosso Corsa paint on the body, and to keep the engine fluids in-phase and without rapid degradation.

 

No problem - that's why we all like the spirit of the online debate - so we can all understand our machines better, and have mental exercises!

 

oh that's just a lot of hot air! hehe.. just kidding

Ray

 

There are no plates after all.....
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I just looked again...and I do have those plates!!!!

 

Was this thread ever solved, did anybody ever call Ferrari or get an expert opinion ?

 

and you see the exhaust much better without them, you just need to use some black plastic ties on the cables on the left hand side

 

the heat is indeed phenominal on the grill without them, I could genuinely imagine its a safety reg, re; heat on external car body parts