Lotus Elan and Lotus Elan Plus 2 Forums

hmmm, thanks for all the feedback and looks like a bit of a debate as to whats what.

Christian - thanks for the pics, I have ordered the TTR header unit just now (and a few other goodies). I guess I should say....Chr?tien - mercis des photos et de l'information, beaucoup appr?ci?s. Votre ?lan de picoseconde semble grand !

With the car only having been on the road for the last 10 months I am not going to mess around with the radiator or fan at this stage, they do the job well enough and the radiator is a triple core from a VW Golf. The header is mainly to make sure I get the system full and I figure the more capacity in the system the better. Also a tight fit to have the fan anywhere other than in front of the radiator

gordont wrote:the radiator is a triple core from a VW Golf.

Another subject for debate - I'll put the proposition that a three core radiator is not necessarliy the best for an Elan. Please comment.

When I bought my radiator I made sure it was three core, and when looking at it side by side with a two core radiator, I had the distinct feeling I'd made a mistake.
In theory the three core should be better, but in Elan practice I'm not so sure.

I could be wrong, not for the first time, but the small air intake of the Elan may not be sufficient to efficiently feed the closer knit three core as well as it can feed a two core - particularly at low speeds.

Fuel injection systems need them before the high pressure fuel pump to stop them running dry as the tank gets low

That's definitely not a swirl pot! It's just a small fuel tank feeding the high pressure pump that is usually constantly filled by a low pressure pump, and sometimes the return from the fuel rail. It is only there to ensure the HP pump has a constant fuel supply (no float chambers on fuel injection!)

Here's my 'swirl' pot in my old single seater. The two hoses passing through the panel on the rhs are the feed to the HP filter then the rail, and the return from the fuel rail.

Sorry for drifting off topic!

Wyn

But Steam occurs when the Coolant boils & the Water will boil off first (according to the Text Books)
Under Atmospheric pressure that will be at 100?C.
The Coolant Filler Cap is designed to permit the System to work at higher pressure & a Cap rated at 1bar raises the Boiling Point to 120?C.
However the Thermostat in a Twincam is usually rated at around 80?C & that temperature can usually be maintained with a fully working cooling system.

Nevertheless, as has so often been repeated here, a header Tank with the Filler Cap at the highest point (including the Heater where possible), is the best way of ensuring that the system is completely full with coolant & that any trapped Air has a place to go outside of the Engine.
I know of no modern Car that has a Swirl Pot but all have a header Tank connected into the Primary (small) cooling system
.
But IMHO the inclusion of a Header Tank into an existing cooling system will not lower the coolant temperature.
If it does can someone please explain the Physics to me please?
Cheers
John

Hi Gordon, I have both swirl pot and alloy radiator if you want to have look over them.

cheers

V

On the subject of filling the cooling system, a though just occurred to me (they often do but are usually yampy) that, with an expansion/recovery bottle in the system, wouldn't that top up the system as the engine goes through it's heat cycle?

I'm sure in the past I have found the coolant overflows when I take off the rad cap, indicating that there is more in there than I put in..

Does this sound feasible? Or shall I get my coat?

Robbie

Robbie,

I think you may have stumbled onto a solution for Ethiopian Drought problems.
Maybe when you removed the Filler Cap the Coolant was still hot, in which case it would have expanded.

John

BLOODY HELL!
What a debate this has opened up! Anyway, a few points:
There should never be any gas in the cooling system... ever. Gas is a poor conductor of heat and allows corrosion more easily. That's why I have the thermostat housing filler neck and an expansion bottle (BTW off a Holden Gemini - fits perfectly!). I have moved the radiator into the nose, which is much lower, and so have a capillary line from the RHS top back to the filler neck to prevent an air pocket. But it's the expansion bottle that keeps the system working.
In laboratory conditions, a fan will stall if obstructed from either side; in reality the passive air flow through the radiator is better with the fan downstream, but it probably makes little difference, as Christian will attest.
By far the biggest cooling effect is switching to an aluminium radiator, which out performs the brass one by an order of magnitude. All the other bits and pieces help, but probably to the same level as drilling holes in your ignition key to save weight.
Cheers
Patrick
PS. Sydney? Pah! Now Brisbane gets really hot!

D.J.Pelly wrote:Robbie,

I think you may have stumbled onto a solution for Ethiopian Drought problems.
Maybe when you removed the Filler Cap the Coolant was still hot, in which case it would have expanded.

John

Either that or my car does a reasonable impression of the USS Enterprise..

Yes, the bit about the warm coolant occurred to me. After I had posted

Coat on

Robbie

We have some folks that are experts in this field on the forum and maybe they can explain the thermo-conductivity of free eleltrons in metals better than I can. Silver seems to be the best and then copper and gold and then aluminum. I believe that the figures given are for a pure substance.

http://www.interfacebus.com/Reference_heat.html

Thermal Conductivity for Different Metals

Metal [Material] Symbol, Atomic Thermal Value
Silver Ag 4.08
Copper Cu 3.94
Gold Au 2.96
Aluminum Al 2.18
Beryllium Be 2.00
Tungsten W 1.74
Rhodium Rh 1.50
Molybdenum Mo 1.46
Chromium Cr 0.937
Nickel Ni 0.92
Platinum Pt 0.716
Tin Sn 0.666
Tantalum Ta 0.575
Lead Pb 0.353
Titanium Ti 0.219
Manganese Mn 0.078

In the real world nothing is pure and we have alloys and they are a bit different when transfering heat.

http://www.engineeringtoolbox.com/therm ... d_429.html

Thermal Conductivity - k - (W/mK)
Material/Substance Temperature (oC) 25 125 225
Acetone 0.16
Acrylic 0.2
Air 0.024
Alcohol 0.17
Aluminum 250 255 250
Aluminum Oxide 30
Ammonia 0.022
Antimony 18.5
Argon 0.016
Asbestos-cement board 0.744
Asbestos-cement sheets 0.166
Asbestos-cement 2.07
Asbestos, loosely packed 0.15
Asbestos mill board 0.14
Asphalt 0.75
Balsa 0.048
Bitumen 0.17
Benzene 0.16
Beryllium 218
Brass 109
Brick dense 1.31
Brick work 0.69
Cadmium 92
Carbon 1.7
Carbon dioxide 0.0146
Cement, portland 0.29
Cement, mortar 1.73
Chalk 0.09
Chrome Nickel Steel (18% Cr, 8 % Ni) 16.3
Clay, dry to moist 0.15 - 1.8
Clay, saturated 0.6 - 2.5
Cobalt 69
Concrete, light 0.42
Concrete, stone 1.7
Constantan 22
Copper 401 400 398
Corian (ceramic filled) 1.06
Corkboard 0.043
Cork, regranulated 0.044
Cork 0.07
Cotton 0.03
Carbon Steel 54 51 47
Cotton Wool insulation 0.029
Diatomaceous earth (Sil-o-cel) 0.06
Earth, dry 1.5
Ether 0.14
Epoxy 0.35
Felt insulation 0.04
Fiberglass 0.04
Fiber insulating board 0.048
Fiber hardboard 0.2
Fireclay brick 500oC 1.4
Foam glass 0.045
Freon 12 0.073
Gasoline 0.15
Glass 1.05
Glass, Pearls, dry 0.18
Glass, Pearls, saturated 0.76
Glass, window 0.96
Glass, wool Insulation 0.04
Glycerol 0.28
Gold 310 312 310
Granite 1.7 - 4.0
Gypsum or plaster board 0.17
Hairfelt 0.05
Hardboard high density 0.15
Hardwoods (oak, maple..) 0.16
Helium 0.142
Hydrogen 0.168
Ice (0oC, 32oF) 2.18
Insulation materials 0.035 - 0.16
Iridium 147
Iron 80 68 60
Iron, wrought 59
Iron, cast 55
Kapok insulation 0.034
Kerosene 0.15
Lead Pb 35
Leather, dry 0.14
Limestone 1.26 - 1.33
Magnesia insulation (85%) 0.07
Magnesite 4.15
Magnesium 156
Marble 2.08 - 2.94
Mercury 8
Methane 0.030
Methanol 0.21
Mica 0.71
Mineral insulation materials, wool blankets .. 0.04
Molybdenum 138
Monel 26
Nickel 91
Nitrogen 0.024
Nylon 6 0.25
Oil, machine lubricating SAE 50 0.15
Olive oil 0.17
Oxygen 0.024
Paper 0.05
Paraffin Wax 0.25
Perlite, atmospheric pressure 0.031
Perlite, vacuum 0.00137
Plaster, gypsum 0.48
Plaster, metal lath 0.47
Plaster, wood lath 0.28
Plastics, foamed (insulation materials) 0.03
Plastics, solid
Platinum 70 71 72
Plywood 0.13
Polyethylene HD 0.42 - 0.51
Polypropylene 0.1 - 0.22
Polystyrene expanded 0.03
Porcelain 1.5
PTFE 0.25
PVC 0.19
Pyrex glass 1.005
Quartz mineral 3
Rock, solid 2 - 7
Rock, porous volcanic (Tuff) 0.5 - 2.5
Rock Wool insulation 0.045
Sand, dry 0.15 - 0.25
Sand, moist 0.25 - 2
Sand, saturated 2 - 4
Sandstone 1.7
Sawdust 0.08
Silica aerogel 0.02
Silicone oil 0.1
Silver 429
Snow (temp < 0oC) 0.05 - 0.25
Sodium 84
Softwoods (fir, pine ..) 0.12
Soil, with organic matter 0.15 - 2
Soil, saturated 0.6 - 4
Steel, Carbon 1% 43
Stainless Steel 16 17 19
Straw insulation 0.09
Styrofoam 0.033
Tin Sn 67
Zinc Zn 116
Urethane foam 0.021
Vermiculite 0.058
Vinyl ester 0.25
Water 0.58
Water, vapor (steam) 0.016
Wood across the grain, white pine 0.12
Wood across the grain, balsa 0.055
Wood across the grain, yellow pine 0.147
Wood, oak 0.17
Wool, felt 0.07

1 W/(m K) = 1 W/(mo C) = 0.85984 kcal/(h m oC) = 0.5779 Btu/(ft h oF)

In the automotive world other factors come into play also like price, ease of manufacture, packaging, and handling, along with some other factors like weight. So what we get now are aluminum radiators with pastic tanks. We used to get all brass and then brass tanks and tubes with copper fins.

Ever pick up a S1 or S2 radiator, about 18 pounds vs an S4 radiator at 8 pounds. I don't have an aluminum alloy radiator out of a Elan to weigh but my guess it its on pare with the S4 unit but the aluminum being around 2.5 times better with the heat transfer you are a bit better than the original S2.
Water or antifreeze do not cool these are just the transfer agents that move the heat from where you don't want it to where the mass of the radiator can give it off.

Most of this is just a bit of spew on my part as I don't know anything...

Gary

"Water or antifreeze do not cool these are just the transfer agents that move the heat from where you don't want it to where the mass of the radiator can give it off."

the name "Coolant" is used because it is a mixture of Water & Antifreeze + any other Pixie Dust that owners put into their "Cooling Systems"
Although this threads has reached almost Marathon heights & don't recall any Post inferring that the Coolant actually cools.
Your list of Materials is impressive Gary but Material selection is, as you have indicated, chosen dependent on several Factors:-
Cost
Suitability for purpose
Cost
Durability
Cost
Weight
and Cost

A typical application/cost problem is the plastic Tanks on Radiators which you mentioned.
These are generally made from a Nylon based, relatively cheap, plastic known as PA 6.6-30% (Polyamid with 30% Glass Fibre Filler)
It is known that Antifreeze (Glycol based) will dissolve PA at higher temperatures.
A risk factor that manufacturers take into account when statistically cooling systems very rarely overheat.

Oh boy we have digressed.
How does a Header Tank improve cooling
Cheers
John

Hi. Cooling systems - always seem to creat heated discussions.

I think the swirl pot design shown earlier should allow a bit of air to collect in the top of the system without it impeding the flow of hot water. So the swirlpot should improve the performance of the cooling system on average - it provides a bit of a buffer. That's not improving the thermodynamic efficiency though, it's keeping the flow of water up so that the heat gets out to the rad. I've noticed before on old engines that blipping the throttle can make the cooling start to work - that's presumably shifting the air pocket down the pipe to the rad cap with increased pressure from the pump. I have Cliveboy's set up as I could understand it better. It lets me fill the system completely to the top in one go, and the length of the neck provides a bit of space for air to collect without blocking the flow of water.

On the position of the fan being in front or behind the radiator, if it's behind, it's sucking on hot air, which is less dense, so to move the same mass of air per second it has to spin at a higher rate. So is this more or less efficient? I'm guessing the fan is powered by a brushed DC motor, so, wear will be higher and efficiency will be lower at higher speed, in general. There's a lower rev limit on DC motors too of course isn't there, where the current is high due to the low back emf in the windings - it's all dependent on what the motor's designed to do - number of windings and area of the brushes and all that - I'm assuming that the rev rate of the fan is high enough when mounted on the front side of the rad pushing air through the rad. Other than this, I can't see what difference the position of the fan will make given that it's possible to seal in either position.

On the conductivity of the metal, it may be more important to be able to paint the rad mat black to get the emmisivity up. For conductivity if I've reasoned this out correctly the amount of heat energy transferred is given by Q = kA(T2-T1)/L in Joules per sec, where k is the thermal conductivity, A is the cross sectional area, L is the length of the 'bar' and T2 and T1 are the temperatures at either end. So, on balance you may do better to use a stronger material even though it may have a lower thermal conductivity, as you can reduce the cross sectional area. Aluminium is great for that in that it's light weight, but relatively inelastic compared to copper. So, to make a strong rad, alumunium sounds appealing.

So that's my twopennorth. At the end of the day the bigger the rad the better in my book.

All the best.

Sean.

Thanks for the feedback, have to laugh though at some of the answers and dialogue......

I will post a pic when the header is in, I never got the answer as to the size of the TTR ones but looks like from Christians pics it will fit fine.

Gordon

PS - as a though does anyone in the UK ever have a problem keeping an elan cool? surely it never gets hot enough!

Round and round we go.

Check the archives, the highest point in the water system is the heater radiator; you will have to fit a bleed valve up there to get the last remaining gas out of the system.