Radiator shrouding

[Phill172]

So I have seen recently alot of people doing this

http://shiftasia.en.made-in-china.com/p ... c-Fan.html

Ignore were its from etc,

Does it have any benifit? Restrict airflow when the fan is not on?

Thanks

[Demlotcrew]

A lot of stock BMW cars use them, but they also incorporate vertical "barn doors" around closed off parts which allows air to flow through the radiator when moving but to remain closed when the fan kicks in and creates a vacuum in the radiator cooling area.

Andrew

[harry_p]

mk2 golfs have a shroud that covers the back of the rad, and on the flat bit beside the fan there are a couple of openings with rubber flaps. i thought it was a pretty clever idea, and very simple to copy.

im sure those shrouds above are great when the fans are running, but look like they could be pretty restrictive in normal driving.

[DanThe]

As has been stated, only any good for making the fans more efficient, but will slow natural airflow big time. Great if you want the fans on all the time

[Demlotcrew]

Slowing the air through the radiator is actually favorable.

[DanThe]

Slowing the air through the radiator is actually favorable.

Favourable for what?

[Demlotcrew]

For maximum efficiency, slow the air, maximize the contact period, remove the energy as heat more efficiently.

That's if you're in the south. Up north air is grim and thus acts un favorably, correct?

[DanThe]

I always thought damp/cold air was the favourite?

I dont understand why you are saying slower air will cool better, the slower your car is travelling the hotter it gets....

[Demlotcrew]

If the car is traveling slower than the minimum air speed needed to cool the engine of course it will overheat. I'm talking about anything above that threshold.

Look at all high performance cars/engines, their air based Cooling devices are always at an angle to the airflow. The same is true for inter coolers on turbo applications.

But of course yours isn't a high performance engine so no need to worry

[DanThe]

So what your saying is your previous statement isnt even relevant to 99.99% of E30's

Have you angled your rad then, mush?

[Demlotcrew]

Standard E30's no, but he has a V8 and the car is used for drifting. There will be little air flow from forward motion when going sideways. The fans willbe on all the time, having the shroud will help the fans reach their maximum efficiency.

The radiator currently fitted to my car is not tilted, that doesn't mean to say the air flowing over it is not slowed down by other means

The DTM rad in the atrium is tilted but I will need to go electric water pump to use it. Will do EWP eventually but not happy with current controllers on the market.

[redcar]

If the car is traveling slower than the minimum air speed needed to cool the engine of course it will overheat. I'm talking about anything above that threshold.

Look at all high performance cars/engines, their air based Cooling devices are always at an angle to the airflow. The same is true for inter coolers on turbo applications.

But of course yours isn't a high performance engine so no need to worry

High performance engines like SR20 and other turbo cars have the Rad tilted. It's so the rad doesn't receive hot air from the inter-cooler as it would do if it were simply mounted directly behind the IC. Allows nice cold air to both IC and Rad. Also allows for shorter IC piping and more space etc.
However, one would only worry about this on a boosted, powerful engine.

[DanThe]

Standard E30's no, but he has a V8 and the car is used for drifting. There will be little air flow from forward motion when going sideways. The fans willbe on all the time, having the shroud will help the fans reach their maximum efficiency.

The radiator currently fitted to my car is not tilted, that doesn't mean to say the air flowing over it is not slowed down by other means

The DTM rad in the atrium is tilted but I will need to go electric water pump to use it. Will do EWP eventually but not happy with current controllers on the market.

Oh right, so pretty much this then \/

As has been stated, only any good for making the fans more efficient, but will slow natural airflow big time. Great if you want the fans on all the time

[Demlotcrew]

If the car is traveling slower than the minimum air speed needed to cool the engine of course it will overheat. I'm talking about anything above that threshold.

Look at all high performance cars/engines, their air based Cooling devices are always at an angle to the airflow. The same is true for inter coolers on turbo applications.

But of course yours isn't a high performance engine so no need to worry

High performance engines like SR20 and other turbo cars have the Rad tilted. It's so the rad doesn't receive hot air from the inter-cooler as it would do if it were simply mounted directly behind the IC. Allows nice cold air to both IC and Rad. Also allows for shorter IC piping and more space etc.
However, one would only worry about this on a boosted, powerful engine.

Harjun, if one wanted to remove any heat soak to the radiator you would put the IC under the radiator or to the side, as per standard S14's.

The reason the rad is tilted is because it increases over all surface area and with the fins not being at a direct horizontal angle to the airflow they create drag slowing the air down and increasing over all efficiency. Good for cooling not good for over all drag. That's why F1 engine run at a higher temperature so they can run smaller radiators as the greater the temperature difference between the air and the water the faster the cooling occurs.

There are of course other factors but generally that's the rule of thumb.

[redcar]

I see, i was just thinking of 700bhp drift cars

Do you have some more info on the velocity of air flow and cooling efficiency? I still don't understand this

[Phill172]

Standard E30's no, but he has a V8 and the car is used for drifting. There will be little air flow from forward motion when going sideways. The fans willbe on all the time, having the shroud will help the fans reach their maximum efficiency.

.

This is what I wanted to hear, although I drive on the road and to events etc I could fab up a shroud that could be a removable item.

My fan set up is a push system so would it have the same effect?

[MillRat]

I guess an analogy would be to run your hand very quickly over a flame; If you do it very quickly then your hand will not get burnt as there is not enough time to transfer enough heat from the flame into your hand to burn. Move your hand slowly over the flame and your hand burns.

Now consider your hand to be air and the flame a hot car radiator. Because you want to transfer as much heat as possible from the radiator to the air passing through the radiator then the slower the air the more time that is available to transfer the heat from the radiator to the passing air (once the air has passed through the radiator the heat transfer process stops). However; if the air speed through the radiator is to slow or stopped, then the air temperature will quickly approach the radiator temperature and heat transfer slows down and will eventually stop. In this situation no cooling is happening (consider the car standing stationary with the engine fan off).

The key is to find the most efficient balance between air speed and heat transfer.

Or have I joined the conversation too late and basically just repeat what someone has talked about earlier?

[DanThe]

I guess an analogy would be to run your hand very quickly over a flame; If you do it very quickly then your hand will not get burnt as there is not enough time to transfer enough heat from the flame into your hand to burn. Move your hand slowly over the flame and your hand burns.

Now consider your hand to be air and the flame a hot car radiator. Because you want to transfer as much heat as possible from the radiator to the air passing through the radiator then the slower the air the more time that is available to transfer the heat from the radiator to the passing air (once the air has passed through the radiator the heat transfer process stops). However; if the air speed through the radiator is to slow or stopped, then the air temperature will quickly approach the radiator temperature and heat transfer slows down and will eventually stop. In this situation no cooling is happening (consider the car standing stationary with the engine fan off).

The key is to find the most efficient balance between air speed and heat transfer.

Or have I joined the conversation too late and basically just repeat what someone has talked about earlier?

Yes, this is the key, but as Andrew stated -

If the car is traveling slower than the minimum air speed needed to cool the engine of course it will overheat. I'm talking about anything above that threshold.

Unless you know this information you cannot simply state -

Slowing the air through the radiator is actually favorable.