MautoK
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| posted on 30/5/09 at 05:03 PM |
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Airflow through radiator?
What do you have as a grille in your nosecone?
I fitted pierced stainless sheet (1/4 inch dia holes and about 57% hole overall) and an 'MK' stainless steel logo.
 
Front, closer
Is it likely/possible/unlikely that this is impeding the airflow sufficiently to have caused my overheating grief? I'm thinking turbulent flow.
Any fluid dynamicists out there?
Also, I have no vents in the bonnet or sidepanels but the gearbox/prop tunnel is open as is the bottom of the engine bay - so it should be well
capable of losing the hot air.
Anyone have observations or experience on airflow issues?
I've cleaned up the block and head faces and there's no damage evident; used a suction doofah to get the water and a bit of sludge out of
the water jacket and it's cleaner than many I've seen. So tomorrow the head goes back on...
Before getting the last of the water out, I twidded the water pump pulley and could see disturbance to the water, so assume that the pump is OK.
Anyway it's only done 40-50 miles since I refitted it, and if it had been compromised I'd have fitted a new one...
Thanks guys,
John.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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rusty nuts
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| posted on 30/5/09 at 05:31 PM |
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I cut two holes in the rear of my nose cone and three in the rear of the bonnet which dropped the coolant temperature and the under bonnet temperature
considerably
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MautoK
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| posted on 30/5/09 at 05:37 PM |
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Aha! Interesting, Mr Rusty. How big holes?
quote:
Originally posted by rusty nuts
I cut two holes in the rear of my nose cone and three in the rear of the bonnet which dropped the coolant temperature and the under bonnet temperature
considerably
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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rusty nuts
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| posted on 30/5/09 at 05:45 PM |
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Approx six in long and two wide . Will try to post some pictures tomorrow if I can find the camara. Water Wetter will drop the coolant temperature ,
worth a try?
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omega0684
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| posted on 30/5/09 at 07:18 PM |
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have you posted twice tonight, get rid of the mesh and keep the mk grill
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scoop
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| posted on 30/5/09 at 07:41 PM |
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There should be plenty getting through there. You dont want your red getting holed by a stone or something.
Just looked at your new rad pics. Its not still plumbed like that at the header tank end is it?
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MautoK
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| posted on 30/5/09 at 07:44 PM |
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Yes, Alex, this thread and a similar one in 'Bodywork & Exterior'.
John.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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MautoK
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| posted on 30/5/09 at 07:50 PM |
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quote:
Originally posted by scoop
There should be plenty getting through there. You dont want your red getting holed by a stone or something.
Just looked at your new rad pics. Its not still plumbed like that at the header tank end is it?
I'm concerned that the flow through the holes is so turbulent that it throttles the flow, and/or giving rise to turbulent flow through the rad
itself (where you ideally need clean laminar flow).
Do you mean the inverted bottle or the pipework, scoop?
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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MautoK
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| posted on 30/5/09 at 07:53 PM |
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quote:
Originally posted by rusty nuts
Approx six in long and two wide . Will try to post some pictures tomorrow if I can find the camara. Water Wetter will drop the coolant temperature ,
worth a try?
Did you fit the vents because you were actually suffering overheating or to reduce the likelihood of it happening?
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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scoop
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| posted on 30/5/09 at 07:55 PM |
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The pipe work. You seem to have both pipes feeding into one from the over head shot.
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MautoK
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| posted on 30/5/09 at 08:04 PM |
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quote:
Originally posted by scoop
The pipe work. You seem to have both pipes feeding into one from the over head shot.
See what you mean! 
 
Header, overflow, fusebox
The bigger one appearing from the lower right corner tees into the bottom hose (rad out to w/pump); the little one connects the header tank's
overflow to the bleed port at the top of the Polo rad.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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bimbleuk
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| posted on 30/5/09 at 08:05 PM |
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If you want to get technical then buy a second hand Magnehelic pressure differential gauge and measure the presure in front and behind the radiator.
Having lower pressure behind the radiator is more significant than the flow in to the nose cone. In practise you only need about 1/4 the frontal arear
of the radiator (or intercooler) to feed sufficient air. Another tip is to block the gaps around the side of the radiator or fit a cowling to trap air
in front.
The air under the car and down the tunnel is quite turbelent. Side exit vents do appear to be the best solution, preferable quite large ones. As
mentioned previously this also lowers the under bonnet temps quite significantly.
I guess my car is quite a good example as I have an intercooler covering most of the front of the radiator. I use a small Polo rad and an oil cooler
behind that for my Rotrex supercharger oil. I use a Sierra oil/water cooler as well so my coolant is doing quite a lot of work! So far no issues with
cooling my engine on road and track.
[Edited on 30-5-09 by bimbleuk]
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scoop
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| posted on 30/5/09 at 08:08 PM |
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Ok mate. You have u2u 
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MautoK
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| posted on 30/5/09 at 08:40 PM |
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That's one full engine bay you've got there!
If you're dissipating the heat from that lot through a Polo rad then I should be having trouble getting a bog standard 2L pinto warm!
Good idea on the deltaP gauge - might make a locost one from plastic tubes.
John.
quote:
Originally posted by bimbleuk
If you want to get technical then buy a second hand Magnehelic pressure differential gauge and measure the presure in front and behind the radiator.
Having lower pressure behind the radiator is more significant than the flow in to the nose cone. In practise you only need about 1/4 the frontal arear
of the radiator (or intercooler) to feed sufficient air. Another tip is to block the gaps around the side of the radiator or fit a cowling to trap air
in front.
The air under the car and down the tunnel is quite turbelent. Side exit vents do appear to be the best solution, preferable quite large ones. As
mentioned previously this also lowers the under bonnet temps quite significantly.
I guess my car is quite a good example as I have an intercooler covering most of the front of the radiator. I use a small Polo rad and an oil cooler
behind that for my Rotrex supercharger oil. I use a Sierra oil/water cooler as well so my coolant is doing quite a lot of work! So far no issues with
cooling my engine on road and track.
[Edited on 30-5-09 by bimbleuk]
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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C10CoryM
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| posted on 30/5/09 at 09:09 PM |
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bimbleuk has the right idea.
Radiator exhaust is more important than intake. You need to have a lower pressure area behind the rad. Sealing the radiator so that all air has to
pass through the core is also VERY important.
Your grille is not the problem.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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MautoK
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| posted on 30/5/09 at 09:31 PM |
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C10CoryM:
Sounds as if you've found out the hard way!
My situation is possibly not helped by having foam rubber strip effectively sealing the trailing edge of the bonnet to the scuttle.
I feel a run with the bonnet off beckoning...!
John.
quote:
Originally posted by C10CoryM
bimbleuk has the right idea.
Radiator exhaust is more important than intake. You need to have a lower pressure area behind the rad. Sealing the radiator so that all air has to
pass through the core is also VERY important.
Your grille is not the problem.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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rusty nuts
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| posted on 31/5/09 at 07:40 AM |
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John , I put the vent holes in place as a precaution but did notice a large drop on the temperature gauge after doing so.
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