Extra Engine Cooling Pt 1 - Fans and vents

[Bull Bar Cowboy]

Yes Jim same here …………..

I just find it strange that manufacturers would not go to the effort of making sure that it gave as good cooling as water ………the big names would probably insist on this ……….. its all about big time economics ……… the smaller the cooling system the cheaper the manufacturing cost ……….. if you knock a £1 off each unit and say 1 to 2 million units ……… big money in just one component alone ……..

Ian

[MogLite]

I'm busy at the mo ... but just a quick search produced this ....... a GM coolant,

The boiling point at 15psi with up to a 60% mix is impressive ..........

Forget the specs - ITS ORANGE

[Bull Bar Cowboy]

Forget the specs - ITS ORANGE

Andy,

PSML

You really are a tart …………….

Ian

[Hybrid_From_Hell]

erm..............

And its taken you HOW long to work this out

Nige

[will_warne]

OK, Nige, I'll take it back to basics with this but have a look here when I'm done:

Basically, moles are an arbitrary measure of the number of molecules; approximately 6.02 x 10[23] molecules per mole.

All the following figures are taken at room temperature and atmospheric pressure; these won't be the same as the values at running temperature but it gives a qualitative idea of what's going on.

Ethylene Glycol (or Ethane-1,2-diol) is a 2 Carbon chain with an alcohol (-OH) functional group on each Carbon. This has a Relative Molecular Mass (RMM) of 62.1 g/mol and a density of 1.114 g/cm3. => One mole occupies 62.1 / 1.114 = 55.7 cm3/mol

This compares to an RMM of 18.0 g/mol and density of 1.00g/cm3 giving a molar volume of 18.0 cm3/mol.

Glycerol has a boiling point of 563.1 K (or 265.1 *C) this compares to water with a boiling point of 100 *C both at atmospheric pressure. Specific heat capacities are 75.2 J/mol K for water and 148.5 J/mol K.

Basically, this means that water holds 75.2 / 18.0 = 4.18 J/cm3 K ie 4.18 Jules of energy are required to raise the temperature of 1 ml of water by 1 *C (Kelvin are use the same scale as *C but start at absolute zero rather than the freezing point of water). For Ethylene Glycol 148.5 / 55.7 = 2.67 J/cm3 K meaning it takes 2.67 Jules to raise the temperature by 1*C. Qualitatively, this means that it'll take more energy to boil Ethylene Glycol BUT V8s don't like running at 200+ *C

I could now go and work out exactly what'll happen in a closed system at around 100*C for a glycol / water mix but most of the important data is in the link and liquids do funny things (like the volume of the mix doesn't equal the volume of the water plus the glycol and the sums for liquid / vapour co-existence are a bit of a PITA and at these temperatures its an important consideration).

As far as the reasons to use Antifreeze go, in the winter that's pretty obvious However, the mixture will also have a higher boiling point than pure water which'll reduce the chance of a boilover when things get warm. However, you don't really want that to be much higher than 120*C (about a 60% glycol mix at atmospheric pressure and about half that at 15 psi). The other advantage of the additives is to reduce the surface tension of the water. Basically, this is what holds drops of water together and this force is reduced by surfactants like fairy. This means bubbles in the cooling system are smaller and the surface contact, on a microscopic level, with the cooling surfaces in the radiator is massively improved. To be honest, though, I don't know whether glycol does this.

HTHs

[Hybrid_From_Hell]

Have you been stalking that nice physics prof again ?

Basically this is getting silly, seems that antifreeze has some weffect on colling and protect engine from corrosion, by how much I don't know and I am feeling the will to live slipping away....

Where did you copy all that from then ?

Nige

[istruggle2gate11]

This is a very interesting thread guys kudos to Pugwash and Will.

[Hybrid_From_Hell]

Yep

Wills good on Google and other search engines

So Will Does pure water vs Water & Abtifreeze mean engine runs hotter with which route ?

Nige

[muddyplugger]

I am certainly no techy on this but as I understand it:

1. You definately need some sort of surfactant to reduce the surface tension of the water, in order that hot clumps of water are dispersed easily so that cooler water can move in. (Mind you a water pump also helps)

Surfactant Good

2. Specific and Latent heat of vaporisation (My O' level Physics now! and this was something I never fully understood) - but the 'coolant' needs to have a high latent heat, it takes/removes a lot of energy to make it boil, which is particularly important where certain parts of the system are very hot (exhaust valves) so causes local boiling of the liquid and draws the heat quickly. Water has a high specific and latent heat than coolants. Water Good

3. What Pugwash said about density of water, (I think thats what he said), denser fluids carry more heat. Water has a lower specific gravity in comparison to coolant. Coolant Good

4. Boiling points. Water has lower boiling point than that of the Gylcols (but Ethyl glycol is much more fun at boiling point!!!) Coolant Good.

In other words water alone is not the best coolant, it definately needs a surfactant and something to stop it boiling over (bit of Glycol).

So who is going to manufacture the "LR4x4 Summer Coolant" and "LR4x4 Antifreeze"? These could be twin bottles for year round protection. Just drain and replace when needed!

Edited to say: Crikey you guys type fast! There are 4 or so posts since I responded!!

[geoffbeaumont]

All the physical chemistry is making my brain hurt a bit (never did like it much...), but I think in plain English pure water isn't the best solution, neither is pure coolant. Somewhere between these extremes is the optimum mix for cooling. What no-one has managed to figure out - and I'm not even going to attempt it - is what that optimum mix is.

I'd hazard a guess (but guess is all it is) that your 70% mix is too much coolant. If there are lots of complex factors affecting this basic formulae probably aren't going to do more than get us in the right ball park. Has anyone ever done any proper experiments? Presumably the coolant manufacturers have, so what's their advice?

[Bull Bar Cowboy]

Oi Barker are you listening …… or has the physics lessons driven you to sleep

Reduce the coolant to the LR recommended 50% mix ………… make sure a good 88C stat is fitted and the system is bled properly.

Wire up your new fans ………. take it for a slow off road run, working the engine hard……… the temp should be normally at about 88 – 92C and rise toward the 100C as you work the engine. The fans and cooling system should keep the temp at a 100C or below. Once its got to the 100C ……. Stop and see how quickly it returns to 90 ish …… with the fans running you should be able to watch the gauge gracefully fall .

If all else fails …….hold your bowels and pray to lord …………

To be fair to Will, I think he must have studied chemistry and some of it sunk in ……. because he was also spot on in the hydrocarbons thread …………. I checked up……… what he says makes absolute sense regarding the mixing of water and coolant........... right or wrong........ I dunno, but it seems to fit.

BTW: Tell Mr White to wire your fans from two separate feeds, through 2 separate relays….. this will give you some resilience.

Ian

[BogMonster]

Surely the short answer is "RTFB" as most antifreeze bottles I have seen quote a level of protection at say 33% concentration, 50% conc and so on. So if the bottle of Acme Quality Antifreeze reckons 33% does to -20 (for example) and you don't live in a place where you expect it to go below that, use that....

Moles are things what burrow in the garden aren't they?

Too much antifreeze is a bad thing and so is none - because it has anti corrosion properties too. In the "good old days" the "good old boys" here could sometimes be found draining their antifreeze out of Series 3's and replacing it with water to "save it for next winter" and as our shop sells antifreeze it always amuses me the rise in sales just before winter appears .... I think a lot of people "stick a bit in just to be sure"

Alternatively the wisdom from RAVE is:

ANTI-FREEZE

PERCENTAGE CONCENTRATION - 50%

PROTECTION - LOWER TEMPERATURE LIMIT

Complete protection

Vehicle may be driven away immediately from cold,

-33° C (-36° F).

Safe limit protection

Coolant in semi-frozen state. Engine may be started

and driven away after warm-up period, -41° C (-42°

Lower protection

Prevents frost damage to cylinder head, block and

radiator. Thaw out before starting engine, -47° C (-53°

F).

CAUTION: Anti-freeze content must never

be allowed to fall below 25% (pre 99MY) or

50% (99MY on) otherwise damage to the

engine is liable to occur. Anti-freeze content

should not exceed 60% (all models) as this will

greatly reduce cooling efficiency.

And from the V8 Discovery 2 manual (this V8 uses the hideously expensive dayglow pink organic acid antifreeze that smells like a pile of dead f@nnies):

The overall anti-freeze concentration should not fall,

by volume, below 50% to ensure that the anti-corrosion

properties of the coolant are maintained.

Anti-freeze concentrations greater than 60% are not

recommended as cooling efficiency will be impaired.

Not sure that adding Fairy Liquid to the cooling system is wise unless you want to look like you rear-ended a Persil tanker when things get hot

[webbsite]

HFH & Co

there is a product available from Redline and they call it "Water Wetter" it is reputed to act as an anti corrosion agent and most importantly to lower the engine temperature by 10 to 15 degrees C. I beleive that you can get it from Merlin Motorsport.

Roger

[GBMUD]

Sorry chaps, I am not much of a chemist, physics was always my thing in school. I have been left behind with all this talk of wetting agents, moles and such - although I do know what they are! I think that you are over analysing.

I know it was a long time ago but can we refer back to this picture?

I presume that this is your heavy duty, extra thick, re-cored radiator? It certainly looks the biz. Just a couple of questions from a simpleton; Is it me or does it appear to have an insulating layer of mud in it? Perhaps it is the colour rendering on my monitor, would not clean black paint offer the best radiating surface type/colour? The other thing that seems to stand out, and again, it could be an interferance pattern from all those verticle lines; are there enough of the little verticle copper fins between the horizontal water channels? They look a little sparse to me, at least when compared to my Tdi rad. I recon that the cooling area of my Tdi rad is, on an area by area basis, about 30% better than that - by memory. If the rad were to be re-cored with the maximum possible surface area rather than the maximum water capacity then it would surely loose more heat - its primary objective.

I know that when Landrover designed the 90 they did some hot climate testing. I presume that this would have involved driving across the Sahara and the like. Now, I know that Nigel's Eales burns alot more fuel than a 3.5 but surely even the standard cooling setup could cope in Britsh autumn temperatures?

One other thing Nige, before you riddle the whole car in vent holes; what about trying the car without the bonnet fitted? If it no longer overheats then I will admit I was wrong and you can get to it with the hole saw.

FWIW, I made no reference to Google in the production of this post.

Chris

[will_warne]

Yep

Wills good on Google and other search engines

So Will Does pure water vs Water & Abtifreeze mean engine runs hotter with which route ?

Nige

Unfortunatly not, Nige. I spend far too much of my time doing this sort of stuff

OK, this is how I see it. Pure water will take a greater ammount of heat per degree of temperature rise so, theoretically, will run cooler but will boil over faster. In practice it won't run cooler, though, due to high surface tension meaning poor heat transfer inside the block and inside the radiator.

For the summer or a garaged vehicle I'd, personally, go for a arround a 25% antifreeze mix with a bottle of 'waterwetter' or simerlar. This should give a good reduction in surface tension, offer corrosion resistance, give a reasonable depression of freezing point and a good, high, boiling point.

If you're leaving you're vehicle outside in the winter or are travelling anywhere chilly I'd push the mix up to about 50-60%. The reduction in heat capacity will be offset by the lower ambient temperature.

My guess is that LR reccomend 50% because its fairly efficient and won't freeze.

Mudplugger, specific heat capacity, as I mentioned above, is basically a measure of how much heat energy is needed to raise a specific mass of a liquid, solid or gas by a degree. Latent heat of vapourisation is baxsically, the enegy required to turn one mole of liquid into one mole of gas at a given temperature. This is not 0 J / mol at 100 *C at 1 atmosphere, though, as the intermolecular bonds (which are VERY strong for a small molecule) still need to be broken. The same is true in reverse; when steam cools to 100 *C it'll loose heat enegrgy without the temperature reducing as the intermolecular bonds reform.

[FridgeFreezer]

Without wishing to add to the physics, Will's right about the latent heat when boiling / condensing a substance. It takes far less energy to make something boil than it does to make it actually evaporate as steam, and when it condenses down from steam back to liquid it releases this energy. This is why steam burns so much - it's not just water at 100deg, when it condenses on your hand it releases a lot more heat energy than if you dropped water at 99.9deg on your hand.

Who wants to try it?

[Hybrid_From_Hell]

Sorry chaps, I am not much of a chemist, physics was always my thing in school. I have been left behind with all this talk of wetting agents, moles and such - although I do know what they are! I think that you are over analysing.

I agree 101% !!

I know it was a long time ago but can we refer back to this picture?

I presume that this is your heavy duty, extra thick, re-cored radiator? It certainly looks the biz. Just a couple of questions from a simpleton; Is it me or does it appear to have an insulating layer of mud in it?

Erm......sort of yes and no, yes it has a "Light Dusting", no as in is more brown water stains than mud

Perhaps it is the colour rendering on my monitor, would not clean black paint offer the best radiating surface type/colour? The other thing that seems to stand out, and again, it could be an interferance pattern from all those verticle lines; are there enough of the little verticle copper fins between the horizontal water channels? They look a little sparse to me, at least when compared to my Tdi rad. I recon that the cooling area of my Tdi rad is, on an area by area basis, about 30% better than that - by memory. If the rad were to be re-cored with the maximum possible surface area rather than the maximum water capacity then it would surely loose more heat - its primary objective.

Ok, this will be interesting as to what others say....The rad is a "Catapillar Gillot Core", this has far bigger and thicker ribs, these carry MORE water and are far stronger, but the core is more "open" this allows air to still flow through even when mud hits it as the fins are also stepped and angled to encourage cleaning of the matrix. The core is FAR wider, again gives increase in water capacity, and still gives more cooling as the fins are further away yet more of them, If you just made a normal core wider a - it would mud up far quicker, and b - it would be closed to air flow due to the extra thickness.

Its a matter of compromise, but overall it holds around 2.6 litres more than std

Others who have had this rads fitted have all commented on them also being super high quality, as well as helping with cooling, it is a 7 row core

I know that when Landrover designed the 90 they did some hot climate testing. I presume that this would have involved driving across the Sahara and the like. Now, I know that Nigel's Eales burns alot more fuel than a 3.5 but surely even the standard cooling setup could cope in Britsh autumn temperatures?

Yes but being the big bore engine it generates more heat and has a smaller collant jacket to normal as the liners take up more space, it doesn't overheat in road use, just when you dial in loads of revs and work it really hard in mud and gooo,

One other thing Nige, before you riddle the whole car in vent holes; what about trying the car without the bonnet fitted? If it no longer overheats then I will admit I was wrong and you can get to it with the hole saw.

Done that and hence why I am going this route...............

FWIW, I made no reference to Google in the production of this post.

Chris

[GBMUD]

being the big bore engine it generates more heat and has a smaller collant jacket to normal as the liners take up more space

Surely this would prevent the heat from getting from the cylinder into the water in the first place? 'fraid I am out of other suggestions.

I would personaly go for the larger surface area and find a way to keep it clear. SimonR uses a fine Expamet mesh in front of his radiator as he can remove and clean it easily and it keeps the airborne muck out of the rad. His always seems to be running hot too though.

None of this helps get rid of the hot air generated.

Chris

[Hybrid_From_Hell]

Expamet mesh

Any links or info

Nige

[Tonk]

wot size and how much u want?

i might have some kickin round here

[GBMUD]

Expamet mesh

Any links or info

Nige

I had to Google for it but: http://www.expandedmetalcompany.co.uk/ Like the fine mesh you find in American style screen doors.

Chris

[BogMonster]

Just picked up a bottle of antifreeze in the shop downstairs

33% mix protects to -18 deg C

50% mix protects to -36 deg C

How cold is England?

[will_warne]

Just picked up a bottle of antifreeze in the shop downstairs

33% mix protects to -18 deg C

50% mix protects to -36 deg C

How cold is England?

I've seen it drop to -20 several times at night up in Scotland. It doesn't happen very often but you don't want to take the risk. Coming out in the morning to find a cracked block isn't much fun!

[BogMonster]

True but if it is a one night snap frost there is a degree of thermal inertia involved (if that is the right term) - a couple of hours at -20 will not see the block reach anything like that temperature, whereas two or three days at that temp obviously allows everything to freeze to that temp. Which is why fresh water in my outside water pipe doesn't freeze every time we have a frosty morning, only if it remains below freezing for a day or two.

Or you can just move to a total loss cooling system like on our old Fordson Major on the farm, where you just fill it up every morning, nothing but rainwater in it and its never frozen up yet

[FridgeFreezer]

It's not pretty but my dad uses fine garden mesh on the front of his RR, same theory as Si that it stops the worst of the gloop from sticking - and so far it's worked really well for the £0 it cost him (nicked from mum's half of the garage )