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better cooling


Guest GDalzell

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Guest GDalzell

I'm about to refit the engine and will need an electric fan because of the rack and pinion. I've had advice from the experts and read the messages on the 4/4a board. There would appear to be three options; Kenlowe, Pacet or a quality fan from the scrap yard. Why does the Kenlowe now seem out of favour when it would appear to have been used sucessfully for many years; the Pacet is more expensive. If anyone has tried one from another scrap car, what did you use and how did it go? The advantage if I can find the right one is that they come with an integral cowl and mountings.

 

I've seen some competition cars with louvres at the back of the bonnet. This would appear to be a great way of enhancing the cooling - any experience?

 

Finally, your thoughts on oil cooler mounting; - directly in front of the radiator  or behind a custom made hole below the main air intake on the front valance.

 

Cheers, Graham

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Guest Vincent

Hi Gaham:

  I mounted my oil cooler in front of and as close to the rad as possible.In order to still be able to use the starting handle I mounted it at either end on a piece of 1.25" square aluminium tubing with the ends facing forward in order not to block any air.It works perfectly.I also added a thermostat so that the oil only goes through the cooler when it reaches 180F.

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I am getting louvres fitted to my bonnet as well as oil cooler (with thermostat). I cannot give figures yet but the physics of louvres is pretty simple.

 

The problem with most vehicles is not what a lot of people think Ie getting more air "in", in fact that problem is more often getting the hot air "out".

 

What occurs is you get a bubble of hot air trapped inside the engine bay and pressurising it, you can only get more fresh air in as can be equally displaced out.

 

When moving, louvres will help create a low pressure in the engine bay (bornellies theory) excuse the spelling, this should allow a better airflow in.

 

Even when stationary they will help, hot air rises so the more holes to let it out the better.

 

I own a K11 Nissan Micra (should be well known in the UK), I've louvres fitted to the bonnet and did notice an immediate difference, coasting down hills the motor quickly cools off (going by water temp gauge) and also takes longer to warm up (not necessarily a good thing), but clearly they made a difference.

 

Mychael

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Guest GDalzell

Michael,

 

Many thanks. My thoughts exactly when it come to getting the air out. I do wonder if the louves are worth more than an expensive fan. What are your design thoughts on the louves; number, width and gap? Creating a low pressure area under the car would help too but a spoiler on the front of a 3A would be regarded as sacriledge and I would be drummed out of the register!. It would only last a week with my lane.

 

Cheers, Graham

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Andy , yes, that's the one.

Graham,I will be getting a toal of 26 louvres,13 to a side along the flat portion of the bonnet. They will each be about 4.5 inches in width, I cannot give you height or spacing figures.

 

Theoretically with the Bernoulie effect (thanks Andy) there would be a lower pressure over the car then under it. The air  has almost a straight run under the car when compared to the top with bonnet, windscreen etc etc.

 

This might be my imagination but when I've been driving fast (70mph) I've slid my hand down along side the door on the outside. I reckon you can feel a slight waft of hot air coming up from underneath. This would tie in with the high/low pressure flow.

 

Mychael

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Further on that, remembering it's only my opinion, I am of the opinion that although the louvres would allow hot air out, when stationary their pressure effect would be nil and even the best electric fan would not exceed the air able to out and down around the engine.

 

So what I'm saying is unless you could be sure of fairly good traffic flow all the time then I'd still be fitting an electric fan for sitting in traffic on hot days.

 

There is also available here in Australia, a new thing which is an electric water pump, it' fit inline on one of the radiator hoses, can be speed varied and/or thermostat controlled.

Depending on application it can either be a replacement for or adjunct to the mechanical pump.

 

I'm thinking of getting one but space is allready a bit tight in a sidescreen engine bay.

 

Mychael

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In a wet climate like ours, bonnet louvres might not be the best thing. I know at least one owner, having louvres in the bonnet, now complaining that in rainy conditions water comes trough the louvres in the engine bay. Louvres might look nice but if they are worth the cost is another question. With the am in mind I personally have my doubts. If you are really looking for a cooler engine, think about a good quality rad and oil cooler first, than wrap the manifold with heat barrier tape.
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Just to add my thoughts on louvres, up to last year I ran a 1951 Riley 2 1/2 which was one of six that had louvres cut into the bonnet and side panels at Abingdon from new (yes they were made at the same place as those cars!). I had the car for many years and covered 10's of thousands of miles in her. Louvres definitely helped with the cooling as the 2 1/2 was marginal at the best of times. The oil breather was on top and never did I have any problems with oil mist - and there was some after very fast runs! Water I never had problems with even though of course it was a twin high cam with a valley in between except when washing the car when a bin bag over the engine solved the problem. The other big plus is that THEY LOOK GREAT!

A picture when it's done?  Nigel (with TS952 - body being reunited with chassis next week)

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A friend that has a TR with louvres mentioned the water factor but said it's only a problem (and not a major one) if the car is parked in heavy rain and of course washing with a hose.

As to oil mist, think how cool it will look, pulling up at a stop, tossing your silk scarf carelessly over your shoulder then wiping the oil mist from your goggles, how very Biggles. ;-)

Mychael.

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Guest GDalzell

Many thanks to everyone. Your advice is most welcome. A few extra thoughts of my own. The louves in the bonnet should help when its stationary. Hot air rises and there should be an natural flow from under the engine up through the, All right, its not through the radiator but their absence must hinder the fan forced air movement. Its trying to push the air downwards out of the bottom against the natual flow. I'd already planned tot insulate the exhaust.

Thanks to about advice re keeping the windscreen an engine clean. What windscreen? It causes air resistance and if you saw the state of the 1/2 mile farm track up to my place, rain coming in the top is the last of my worries. As you'll gather, this car will not be original or pristine.

 

And finally, thanks for the Bernoulli (this is the correct spelling) references. The pressure is proportional to half the velocity squared. Assuming that the air temperature after it comes through the engine bay is 15 deg K hotter and the pressure above the bonnet is 90% of atmospheric,then the density of the air leaving the engine bay must be 85% of that entering it. This would require the open cross section of the louves to be 17% greater than the open air path through the radiator but as one of you dsaid, it'll look the part.

 

Cheers Graham

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Guest Iain.F

Hi

Just to add my "twopennyworth" to this hot subject (groan - poor pun intended).  Though it is difficult for me to advise from experience as my 3A is still in the assembly stage, there does seem to be merit in the "Trapped hot air" theory, but the problem with any louvres / vents is the positioning of them. A high pressure area at the base of the windscreen could cause a very different effect than expected.

 

My reaction to overheating after checking the obvious things would be to remove the bonnet to see if it was trapped under bonnet hot air.  This would be very simple and easy - try to rule out the obvious.  Anyone looking under the bonnet of a modern car might be surprised how cramped it is and also how small modern car radiators are, so it is still surprising this problem persists with sidescreen cars without a clear answer.  Clearly cooling is marginal and maybe it is time to look at a more effective answer.  

This may seem obvious, but new generations of drivers brought up on modern reliability are now looking at TR's and to enjoy thier use. Several companies have looked at upgrading cars with rack and pinion steering, bigger brakes, fuel injection and even better heaters.  This has helped a lot to make cars more managable in modern traffic conditions.  Is there now a place for an integrated cooling package that "Does what it says on the label".

  Our cars have always been proclaimed to be simple and robust, that is a fundemental part of thier charm.  Perhaps we need to revisit that.  Any thoughts?

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Ian,

Here is a thought. Totally unproved, once again just my humble opinion. My reasoning goes like this, I seem to recall reading somewhere that designers of modern engines reduced the intake area as it was too large, now here's the rub of it.

 

If we try to force too much air into a space it would "fill up" for want of a better description and "spill out" over the sides, in this case the sides being the radiator, like trying to fill a bucket with a hole in it faster then the hole could let the water out, it would overflow back over the top ,,yes??

 

Okay so if the same thing were happening with the air we would not be getting fresh air through the radiator in a smooth even flow, it would be turbulent as it kept trying to keep overflowing back out. If this does indeed happen then would it not affect the heat exchange between radiator and air??

 

Mychael

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Just following on with the other points. Minis with their small radiators never overheated (well mine didn't) so clearly there was efficiency there, albeit they were a smaller motor.

 

As to moderising the cars, at what point would they then cease to be what they were and mearly become some type of parody of the kit cars that try to copy the originals.?

 

Interesting topic for debate I reckon.

 

Mychael

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Does anyone know of a supplier for "Forlife" engine coolant.   It's an antifreeze mixture that's used undiluted and improves cooling effect over plain water considerably.   I think Dr. Michael Bingely has mentioned it in TR Action - anyone got an email address for him please?
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Guest GDalzell

Mychael,

 

As you say, the question of the extent to which a TR should be mofied before it loses its "TR soul" is a subject for debate but not under the topic of cooling a 3A. Why don't you post the question under the general TR Forum discussion listing and get a real debate going.

 

Regards Graham

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Thanks for that Paul, after much searching on the 'net, all I could find was a reference to Toyota Forlife coolant, couldn't find anything like it in Demon Tweeks, but I'll try the code you've given.

 

Added 11.15, yes that's the stuff, I used it in the early 70s in a Hillman Imp, it protects aluminium and alloy part better than A/F and water.

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just a couple of pointers that may help.

i have come across a couple of converted LHD TR3a's from the States with bonnet louvres. i believe this was a factory fitted option for cars going to hotter climates.

after the 3a was first produced a factory air scoop was sent out as a cure for the air bypassing the radiator on the wide mouth 3a's and causing overheating.

you can still get these from moss, revingtons etc. they are only made of fibre board and are quite easy to make yourself out of aluminium sheet.

check the radiator cap - you will find only a rubber seal at the bottom spring loaded section.

the 3a relied on the top of the radiator for expansion, if you overfill it water will run out of the overflow, when cooled down you will see an air pocket at the top of the radiator, not a good idea as this is level with the water pump and circulation hoses.

find your local scrap merchants and have a look for a car with an expansion tank fitted (i used bits from a mark 3 ford cortina!).

i pinched the top rubber seal from the filler cap (don't use the cortina filler cap as it is rated at a higher pressure) and put this on my own cap.

i also took the tube and expansion tank and mounted this by the left front suspension mounting under the bonnet. connected the tube to the overflow on my rad (same size luckily) and made sure it went to the bottom of the expansion tank.

filled up the rad, half filled the expansion tank and ran her up to temperature and watched the water level in the tank go up by about 40mm.

left her to cool down and 'low and behold' the water level went back down, took the cap off the radiator and 'hey presto' a full radiator.

now running her as a sealed cooling system TR3a with no worries about loosing water.

just like the 4a but without spending a fortune on the conversion kits you can buy.

even the scrappy gave me the bits for nothing!

have fun

pete :D

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