Charlie_Zetec
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| posted on 22/8/11 at 09:43 PM |
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Raceline water rail rad cap Q
Evening.
Having ordered my Raceline water rail some 6 and a bit weeks ago, I called to chase it the other day. I was told that they hadn't completed the
order because they were waiting on stock of pressure caps from the States, and long overdue despite repeat promises of imminent delivery.
No being the impetuous person I am, I suggested not to worry and send me the rest of the kit anyway, and I'd source my own rad pressure cap from
the local motor factors and contacts I've got. But true to form, nothing is that simple. Local motor factors could get me a replacement cap to
fit, but the pressure was only 13PSI, which Raceline said was too low. They supply an 18-22PSI cap, and for the love of me, can't find a
replacement through any sources at Ford or otherwise to match.
So I turned to the dreaded of all places, eBay....
Stumbled across the two following options, but I'm unsure as to which would be the better choice. So I thought I'd ask for opinions here
and see what the general concensus was before I made a decision. Please be brutally honest - I'm sure some have encountered this or similar
problems in the past, so those in the know, please speak up!
Options are as follows;
eBay - The UK's Online Marketplace
eBay - The UK's Online Marketplace
Let's hear your thoughts!
Artificial intelligence is no match for natural stupidity!
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Tiger Super Six
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| posted on 22/8/11 at 10:02 PM |
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Hi, I have the raceline set up and it is a stant cap which looks similar to the second link but it doesn't have the red bit on the right hand
side. I am not sure if.that one will fit. I can take a pic of mine if you want?
Mark
Tiger Avon
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jeffw
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| posted on 23/8/11 at 05:28 AM |
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The 2nd one is the one I have in mine.
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Greenie
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| posted on 23/8/11 at 06:52 AM |
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Hi where did you get your water rail from, I was considering one for my 2ltr Zetec Blacktop?
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cliftyhanger
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| posted on 23/8/11 at 07:48 AM |
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I am sure mine ran with a std 13lb cap. Not sure why they suggest a 20lb one is needed, unless expecting to run very high temps (and therefore
pressure)
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Charlie_Zetec
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| posted on 23/8/11 at 08:32 AM |
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quote:
Originally posted by Greenie
Hi where did you get your water rail from, I was considering one for my 2ltr Zetec Blacktop?
Hi, I got my water rail from Raceline direct, Raceline website
They're a bit behind on orders at the moment because of missing rad caps, but apart from that have been very helpful!
I believe Burton Power also stock them, but assume they get them from Raceline to market. And are therefore probably dearer, knowing them!
[Edited on 23/8/11 by Charlie_Zetec]
Artificial intelligence is no match for natural stupidity!
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Charlie_Zetec
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| posted on 23/8/11 at 08:34 AM |
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quote:
Originally posted by cliftyhanger
I am sure mine ran with a std 13lb cap. Not sure why they suggest a 20lb one is needed, unless expecting to run very high temps (and therefore
pressure)
I thought that too - 98% of all the Ford rad caps I looked at in the catalogue with the local specialist are 13, but Raceline definitively said they
use, supply (when in stock), and recommend a higher pressure one - hence the post.
I would normally be happy with a 13'er, but don't want to go against manufacturers guidelines, which is why I'm hesitant and holding
out for a specific answer....
Artificial intelligence is no match for natural stupidity!
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MkIndy7
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| posted on 23/8/11 at 11:02 AM |
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Wouldn't the standard radiator cap pressure be for a system that has a header tank and thus more volume for the water to expand into so it
doesn't reach blow off pressure.
If the Raceline setup has no header tank that'll be why it requires a higher rated pressure cap.
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britishtrident
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| posted on 23/8/11 at 11:52 AM |
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quote:
Originally posted by MkIndy7
Wouldn't the standard radiator cap pressure be for a system that has a header tank and thus more volume for the water to expand into so it
doesn't reach blow off pressure.
If the Raceline setup has no header tank that'll be why it requires a higher rated pressure cap.
For all practical purposes water is incompressible fitting a higher pressure cap won't hold the coolant in.
It is all to do with temperatures and boiling points.
These figures are for plain water, any glycol content in coolant will push the boiling point up a few degrees.
At 13psi above atmos water will boil at about 119c
At 20psi above atmos it water will boil at about 127c
Most modern cars use 1.5 bar (approx 21psi) caps because they can run surprisingly close to 120c in some situations.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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procomp
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| posted on 23/8/11 at 12:22 PM |
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Hi
The reason they specify the use of the higher poundage cap is because the thermostat is so far from the engine it's self that by the time the
thermostat See's the temp to open the actual engine temp is far higher. IE poor design and the reason why they are generally frowned upon. Some
get them to work others just change to more reliable setups.
Cheers Matt
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MkIndy7
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| posted on 23/8/11 at 12:24 PM |
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In a header tank setup you don't fill it to the top so there is quite a large air pocket that can compress so it doesn't go
overpressure.
In the raceline setup there might be a tiny amout of air held in the top of the rail if any at all so there is very little for the hot water to expand
into I suspect that's why it needs a higher pressure cap.
On a sealed heating system like your Combi at home you have an expansion vessel half filled with air that the water expands into..
When cold the system pressure is 1 bar
When the system is warm the pressure rises to 1.5 bar
The safety valve is set at 3 bar and thus doesn't blow off
When it cools it returns to 1 bar
When the expansion vessel has lost it's pressure or burst there is nowhere for the water to expand to.
When cold the system pressure is still 1 bar
When the system warms up the water has nowhere to expand to
The safety valve now blows off as it maybe reaches 3.5 bar and thus above the 3bar limit
If you'd fitted a 4 bar safety valve because you knew it had limited expansion then the system wouldn't have blown off, this I what I
suspect there trying to achieve.
Different application but same principle I'm sure without knowing too many of the technicalities
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britishtrident
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| posted on 23/8/11 at 01:02 PM |
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quote:
Originally posted by procomp
Hi
The reason they specify the use of the higher poundage cap is because the thermostat is so far from the engine it's self that by the time the
thermostat See's the temp to open the actual engine temp is far higher. IE poor design and the reason why they are generally frowned upon. Some
get them to work others just change to more reliable setups.
Cheers Matt
Indeed I 100% agree the design shows a lack of understanding of how cooling systems work only way to bodge it to get it (sort of) working is
drilling holes in the thermostat standard Ford set up is superior.
It is a pity the other external thermostat solutions such as the excellent Rover PRT lack bling in fact are down right ugly..
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 23/8/11 at 01:07 PM |
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quote:
Originally posted by MkIndy7
In a header tank setup you don't fill it to the top so there is quite a large air pocket that can compress so it doesn't go
overpressure.
In the raceline setup there might be a tiny amout of air held in the top of the rail if any at all so there is very little for the hot water to expand
into I suspect that's why it needs a higher pressure cap.
On a sealed heating system like your Combi at home you have an expansion vessel half filled with air that the water expands into..
When cold the system pressure is 1 bar
When the system is warm the pressure rises to 1.5 bar
The safety valve is set at 3 bar and thus doesn't blow off
When it cools it returns to 1 bar
When the expansion vessel has lost it's pressure or burst there is nowhere for the water to expand to.
When cold the system pressure is still 1 bar
When the system warms up the water has nowhere to expand to
The safety valve now blows off as it maybe reaches 3.5 bar and thus above the 3bar limit
If you'd fitted a 4 bar safety valve because you knew it had limited expansion then the system wouldn't have blown off, this I what I
suspect there trying to achieve.
Different application but same principle I'm sure without knowing too many of the technicalities
Modern engines are designed to run hot ISTR The standard Mondeo cooling fan is controlled by the ECU to only switch to full blast at 115c
---- 13psi cap would pop just before that which would trigger boiling. .
[Edited on 23/8/11 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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MkIndy7
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| posted on 23/8/11 at 01:30 PM |
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quote:
Originally posted by britishtrident
Modern engines are designed to run hot ISTR The standard Mondeo cooling fan is controlled by the ECU to only switch to full blast at 115c
---- 13psi cap would pop just before that which would trigger boiling. .
[Edited on 23/8/11 by britishtrident]
I agree, But the original posting appeared to be why if at all it needs an exceptionally high, rare pressure cap...
Which I was suggesting it may require as there was no header tank in their water rail installation design and thus they require the high pressure cap
to overcome this.
If the Standard Mondeo one was man enough for the job they'd just use that, so it must be due to another reason (like lack of expansion) that
they have to use a higher rated one.
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procomp
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| posted on 23/8/11 at 01:38 PM |
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Hi
They use an expansion tank system rather than a header tank system to over come that scenario. All in all it's a cock up off a design. Also if
you look at where the water goes around the corner in the casting you'll see on some that the orifice is way too small ( little finger tip size
) and on another it is twice that size. !!!
Cheers Matt
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Tiger Super Six
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| posted on 23/8/11 at 04:27 PM |
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If it's such a 'cock up' of a design, how has it successfully been raced in Formula Ford for years?
Also, if this the Zetec or Duratec appliction, the duratec (which I have) retains the thermostat in exactly the same position as the original,
it's not in the water rail at all.
[Edited on 23/8/11 by Tiger Super Six]
Mark
Tiger Avon
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procomp
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| posted on 23/8/11 at 05:01 PM |
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Hi
As i stated earlier some do get it to work by bodging it. The Zetec one has the thermostat something like 10" away from original fitment. If you
do some basic looking / research you will see that there are many many people who ditch the rail and return to a plain old system and cure all the
problems the rail induced into there previously perfectly good working system. There is a reason why so many come up for sale SH.
Cheers Matt
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Greenie
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| posted on 23/8/11 at 06:49 PM |
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Cheers Charlie..........
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