Is a rad cowling a good idea?

[bitsilly]

I have been lucky enough to find a newly rebuilt 3 core SD1 and had planned on fitting a fan with a full cowling to maximise air flow cooling when the fan is on. BUT. Chatting to the seller of the rad he got me thinking that a cowling would restrict air flow through the radiator in normal use when the fan is not on. I know that if that is true the fan would simply come on and cool but I had thought it was a no-brainer and now it aint!
So is a full air tight cowling a good idea or not?

ps I have tested the rad with my compressor but what is the normal running pressure of the water?

[nbracken]

I don't understand why the cowling would deteriorate the normal cooling effect as it forces air through the rad in any condition rather than allowing air to pass arround it.

[Clarkson]

Originally Posted by bitsilly

I have been lucky enough to find a newly rebuilt 3 core SD1 and had planned on fitting a fan with a full cowling to maximise air flow cooling when the fan is on. BUT. Chatting to the seller of the rad he got me thinking that a cowling would restrict air flow through the radiator in normal use when the fan is not on. I know that if that is true the fan would simply come on and cool but I had thought it was a no-brainer and now it aint!
So is a full air tight cowling a good idea or not?

ps I have tested the rad with my compressor but what is the normal running pressure of the water?

I am thinking about doing the same thing on my SD1 rad, I am gonna make up a aluminium box on the back of rad and mount my cooling fan on it, that way it will cool the whole rad.!:thumb:

[bitsilly]

Ditto!
When a cowling is fitted the only path for the air is through the fan. The question is would effectivley blanking out say 50% of the air flow by fitting a cowling?
I would still say that its a good idea as it would come into its own in a traffic jam! Just curious as to how it affect normal cooling!

[Clarkson]

Originally Posted by bitsilly

Ditto!
When a cowling is fitted the only path for the air is through the fan. The question is would effectivley blanking out say 50% of the air flow by fitting a cowling?
I would still say that its a good idea as it would come into its own in a traffic jam! Just curious as to how it affect normal cooling!

I don't think so and That's what I am gonna do. I also think your fan will have more control over the cooling system.:thumb:

[dingocooke]

A cowling is good when a fan is running constantly (ie a mechanical fan driven of the water pump), because the cowling stops the air being drawn from the side of the blades rather than through the rad core.
However (why is there always a however??) when the fan is not running the cowling will restrict the airflow over the core of the rad.
If you think about it to get the same volume of airflow through the cowling fan diameter area as the larger radiator area, the air needs to be travelling at a higher speed.
So for a given road speed, with no fan running, the cowled rad will have less airflow through it.
If you dont believe this check out various factory built mass produced cars underbonnet; you will see older mechanical fanned cars with cowls, and newer thermostatically switched electric fanned cars have no cowl, just a peripheral ring to stop fap tip washout.


So, dont fit a cowling

[Clarkson]

Originally Posted by dingocooke

A cowling is good when a fan is running constantly (ie a mechanical fan driven of the water pump), because the cowling stops the air being drawn from the side of the blades rather than through the rad core.
However (why is there always a however??) when the fan is not running the cowling will restrict the airflow over the core of the rad.
If you think about it to get the same volume of airflow through the cowling fan diameter area as the larger radiator area, the air needs to be travelling at a higher speed.
So for a given road speed, with no fan running, the cowled rad will have less airflow through it.
If you dont believe this check out various factory built mass produced cars underbonnet; you will see older mechanical fanned cars with cowls, and newer thermostatically switched electric fanned cars have no cowl, just a peripheral ring to stop fap tip washout.


So, dont fit a cowling

Sorry, I have to disagree with you, cause most Audi cars have a raditor cowlings with electric fans mounted to them and works fine....???

[wilf]

I think that the various contributors to this thread have very different ideas as to exactly what is meant by a "cowling".

Hence the conflicting opinions.

[shadow]

I'm no expert, But here's my view.

Picture the cowling fitted to the back of the rag with the fan in the middle.

Exaggerated example!!!!: Big funnel with fan on spout. Try to blow into the wide end of a funel and this would be a crude example. ok if there is a fan sucking air from a wide area through a smaler area around the fan surrounded by the cowling, but not as good as free flowing through the rad while the fan is off....


Told you I'm no expert, so I'm going to take the funnel off my rad cos it looks stupid.

Hmm Absinth..

[Clarkson]

Originally Posted by shadow

I'm no expert, But here's my view.

Picture the cowling fitted to the back of the rag with the fan in the middle.

Exaggerated example!!!!: Big funnel with fan on spout. Try to blow into the wide end of a funel and this would be a crude example. ok if there is a fan sucking air from a wide area through a smaler area around the fan surrounded by the cowling, but not as good as free flowing through the rad while the fan is off....


Told you I'm no expert, so I'm going to take the funnel off my rad cos it looks stupid.

Hmm Absinth..

Still disagree! there is gonna be a 16" to 18" hole in the panel...so how can this be restricting air flow through the raditor?? Your electric fan will be more effecient and probably won't run so long because of good airflow.:thumb: