Why do I have two fans?

[8thTon]

I would have to say it's a great idea knowing how hot it gets under that hood, like today, must get well over 200! And don't forget no matter how many fans there are, the air has no way to escape, it would be even hotter so if you're stuck in traffic.

I've I've always why automotive design has always kept the heat under the hood instead of designing in
ways for the heat to escape

It blows out the bottom....

 

[Dirtman]

It blows out the bottom....

Well not if you're careful and lube it properly...

 

[Denisefwd93]

It still stays hot up there no matter where you're blowing it! ?

 

[8thTon]

Well that deteriorated quickly...

 

[Denisefwd93]

Well if you want to keep it serious we could would use a remote sensing thermometer like I used to have in the business, put the probe under the hood on a nice hot summer day, drive in traffic, stopped, and at interstate speed. Maybe I'm wrrwrrr... wrong! There's all kinds of heat sources under the hood, manifolds being the hottest 6-800*, engine coolant 190+-, ac condenser 130-+ radiator coolant temp + the AC condenser temp.

Air will stagnate stratify and the cool air will move under it not replace it necessarily.

if you've ever been to an amusement park where they have air conditioning under the canopy with the people standing in line.... y'all ever wonder how they can do air conditioning outdoors like that?

anyway not trying to pick a fight or having a knock-down drag-out argument ?

 

[Dirtman]

I trust you with all things cooling related...

 

[Denisefwd93]

It has my own curiosity piqued! I used to have an electronic thermometer with multiple probes, now we all use those handheld infrared units which is kind hard to use on a moving vehicle!

I have it an electronic thermometer used in the kitchen that has probe wonder if that would work? Probably would!

Okay little ranger bend ove....er no open wide!?

 

[Dirtman]

My dmm has a temp probe that goes up to 1500f. Ive used it to cook turkey and test cats.

 

[pjtoledo]

I would have to say it's a great idea knowing how hot it gets under that hood, like today, must get well over 200! And don't forget no matter how many fans there are, the air has no way to escape, it would be even hotter so if you're stuck in traffic.

I've I've always why automotive design has always kept the heat under the hood instead of designing in
ways for the heat to escape

probably a hold over from the days when oil mist from engines would cover the windshield, and passengers.

 

[8thTon]

Well if you want to keep it serious we could would use a remote sensing thermometer like I used to have in the business, put the probe under the hood on a nice hot summer day, drive in traffic, stopped, and at interstate speed. Maybe I'm wrrwrrr... wrong! There's all kinds of heat sources under the hood, manifolds being the hottest 6-800*, engine coolant 190+-, ac condenser 130-+ radiator coolant temp + the AC condenser temp.

Air will stagnate stratify and the cool air will move under it not replace it necessarily.

if you've ever been to an amusement park where they have air conditioning under the canopy with the people standing in line.... y'all ever wonder how they can do air conditioning outdoors like that?

anyway not trying to pick a fight or having a knock-down drag-out argument ?

Oh I understand that, but that engine driven fan can move a lot of air even at idle, and of course at speed there is no lack of air movement. It doesn't have far to go to exit down and to the sides. You can tell by the shields and covers they put on modern cars that considerable attention is paid to how the air moves.

 

[sgtsandman]

Hood and/or fender vents cost extra money in manufacturing. Since they aren't mandated of absolutely necessary for the average Joe's vehicle, no manufacturer will want to add them. Hood vents would probably be the most beneficial but then you have precipitation coming down on the otherwise mostly protected engine. Fender venting would cost even more and be more complex but less precipitation issues.

 

[85_Ranger4x4]

It has my own curiosity piqued! I used to have an electronic thermometer with multiple probes, now we all use those handheld infrared units which is kind hard to use on a moving vehicle!

I have it an electronic thermometer used in the kitchen that has probe wonder if that would work? Probably would!

Okay little ranger bend ove....er no open wide!?

If you have a manual remove the shift boot and crack a window going down the highway, the amount of hot air from the engine bay travelling under the truck is incredible.

 

[adsm08]

It does not blow the heat out the bottom. That would be inefficient as heat rises.

If you look at the design of the fan shroud. and even more at the design of some newer cars with the lower shields the idea is to move the heat along through the engine bay and out the back of the vehicle.

Like 85 said, open up a hole in the floor around the shifter plate and see how much heat comes in. In the summer it is uncomfortable at best, even at a stop. In the winter it can almost replace having the heater running.

Air moving over the outside of the block helps cool the engine just as much as air moving over the radiator. One guy I used to work with ran demo cars when he was younger. He said first thing he'd do to prep a car was yank the rad and run long lengths of coolant and transmission line around the engine bay for cooling. The rubber hoses weren't as prone to taking damage as a stiff metal rad and if made long enough would cool just as well.

 

[Uncle Gump]

It does blow it out the bottom... why... because that is the only place it can go.

While I'm sure that some heat transfer takes place passing air over the engine... to say it cools the engine "just as much" as passing air through the radiator is a huge stretch. Maybe if they set the engine in a big heat sink or cast cooling fins onto the block and cylinder heads that theory might hold more true.

Thinking back to my engineering days... I do believe that some of the underbody shields had an FNA that placed them into engine cooling. Not that they cooled the engine but rather helped expel the heat generated by the engine from the engine bay.

 

[8thTon]

It does not blow the heat out the bottom. That would be inefficient as heat rises.

If you look at the design of the fan shroud. and even more at the design of some newer cars with the lower shields the idea is to move the heat along through the engine bay and out the back of the vehicle.

I think we're saying the same thing, but in order to get out the back the air must go down to get out of the engine compartment. And when the vehicle is not there is nothing to make make it go out the back - you just have airflow from the fan. The shortest path is to the sides, or out the front wheel wells if they are open.

I think on my Ranger the wheel shrouds don't go down that far, so that is the likely exit at rest. I'll have to look when I finish my coffee.