MautoK
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| posted on 30/5/09 at 04:14 PM |
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Nosecone grille
Just a thought about causes of overheating...
I've currently got the head off my Pinto engine and everything looks good; there's no damage to the gasket and the head and block faces are
good.
I was looking at the nosecone and I have pierced stainless sheet as a grille with an 'MK' logo behind it:
 
Front, closer
The metal has 1/4 diameter holes and I've worked out that it is 57% hole / 43% solid. With the logo that brings it closer to 50/50. My concern is
that this may be impeding air flow to the radiator - causing sufficiently turbulent flow around the holes to prevent adequate overall flow.
I'm no expert on fluid dynamics - can anyone throw any light on the flow regime through a grille like this?
Has anyone fitted a grille like this and suffered overheating, then removed it and been OK?
The reason for fitting it was that it seemed holey enough yet robust enough to stop grit and stones impacting the radiator.
I also have no vents in the bonnet or side panels to aid dispersal of the hot air - does anyone have any observations or experiences of vents/no vents
and overheating?
Thanks guys and gals,
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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omega0684
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| posted on 30/5/09 at 06:51 PM |
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get rid of the mesh and leave the MK sign
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MautoK
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| posted on 30/5/09 at 07:11 PM |
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That's what I'm heading towards, I think. But I didn't want to leave the radiator so vulnerable to flying rocks. Maybe look out for
the woven steel mesh that's more like 90% hole.
Just wondering if anyone else had run with & without something like I've got by way of comparison.
quote:
Originally posted by omega0684
get rid of the mesh and leave the MK sign
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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speedyxjs
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| posted on 30/5/09 at 07:27 PM |
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As you say, get a really fine mesh to go in front and you should be fine 
How long can i resist the temptation to drop a V8 in?
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mr henderson
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| posted on 30/5/09 at 07:32 PM |
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I think the problem is more likely to be the lack of a suitable exit for the hot air. That's what I would be looking into first. Maybe try an
experiment, is there some way you could wedge the back of the bonnet open a couple of inches, and try it like that?
John
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MautoK
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| posted on 30/5/09 at 09:00 PM |
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Once I've got the head back on, I'll try a quick blat with the bonnet removed and compare with it fitted. If there's a significant
difference then I may well do a little surgery on the bonnet.
Thanks, Mr H
John.
quote:
Originally posted by mr henderson
I think the problem is more likely to be the lack of a suitable exit for the hot air. That's what I would be looking into first. Maybe try an
experiment, is there some way you could wedge the back of the bonnet open a couple of inches, and try it like that?
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 09:05 PM |
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What I don't understand is there's folks out there running massive bhp and breezing it with the Polo rad, yet my bog standard 2L is making
me a cup of tea after 5 miles!  
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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dave r
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| posted on 31/5/09 at 07:44 AM |
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does all the air comming in thru the nosecone have to go thru the rad, or are there gaps around it ?
on my 2b i found this made the biggest difference as to how hot it got
dave
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RK
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| posted on 31/5/09 at 01:56 PM |
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I have a Nissan tech for a client, and he told me that Nissan's have a habit of overheating regularly. It is due to the rad being lower than the
head, so the water doesn't flow properly, and introducing air into the cooling lines (don't ask me how this happens!!).
I have a Nissan engine, and he said to raise the overflow bottle to at least 10 cm above the head and wait for the bubbles to come out of the line.
Long term, find a way to get the system free of bubbles. This is helped by raising the top of the rad over the engine head.
I hope this can help.
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MautoK
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| posted on 31/5/09 at 07:05 PM |
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quote:
Originally posted by dave r
does all the air comming in thru the nosecone have to go thru the rad, or are there gaps around it ?
on my 2b i found this made the biggest difference as to how hot it got
dave
Dave:
There is a gap, but the rad is fairly close to the grille - probably 3 or 4 inches - and there's a couple of inches gap each side to the
nosecone. I may well knock up some baffles to persuade air through the rad.
quote:
Originally posted by RK
I have a Nissan tech for a client, and he told me that Nissan's have a habit of overheating regularly. It is due to the rad being lower than the
head, so the water doesn't flow properly, and introducing air into the cooling lines (don't ask me how this happens!!).
I have a Nissan engine, and he said to raise the overflow bottle to at least 10 cm above the head and wait for the bubbles to come out of the line.
Long term, find a way to get the system free of bubbles. This is helped by raising the top of the rad over the engine head.
I hope this can help.
Thanks RK
The water level is higher in the rad than in the engine and the header tank is higher still.
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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TheGecko
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| posted on 31/5/09 at 11:58 PM |
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quote:
Originally posted by MautoK
There is a gap, but the rad is fairly close to the grille - probably 3 or 4 inches - and there's a couple of inches gap each side to the
nosecone. I may well knock up some baffles to persuade air through the rad.
The air will always take the path of least resistance and a couple
of inches of open space will offer a lot less resistance than the radiator core. Fix that and I suspect you'll resolve some of your problem.
Also, as others have said, make sure the air has some way out of the engine bay too.
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40inches
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| posted on 1/6/09 at 11:52 AM |
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Check this thread for ideas http://locostbuilders.co.uk/viewthread.php?tid=114397 and sealing between the rad and nosecone makes a huge differance.
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