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MilesA

Oil cooler position

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I posed this query having seen the recent Binky episodes and seen the 3 radiators installed hard up against each other at the front of the car.

I have an oil cooler that is located close to the grille of my 3A and so about 9 inches forward of the radiator. This is fairly common positioning in other examples I have seen.

So my query is, would radiator performance be improved if the two were closer together / adjacent or is any adverse impact on the radiator's performance from the 9" gap with the cooler, negligible?

If I was serious about this I would of course reposition the cooler at the bottom of the apron with its own opening, although I have seen photographs of one mounted vertically alongside a 3A's radiator.

Equally, I am aware that an oil cooler is probably not necessary on a non-racing car, so perhaps I should just remove it!

Miles

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Took the oil cooler off my car last year and have noticed an increase in engine water temp since doing so.  Noted by the fact the cooling fan comes on more frequently.  I have not noted any oil pressure issues so far.  My last long run was from Portsmouth to N London keeping up with traffic and getting stuck on the M25 car park for 1/2 hr. - oil pressure remained as I have always observed.

 The cooler take off kit I have is the orig Lawrence Tune thing that screws to adaptors on the side of the filter bowl and the top of the filter head.  Filter change meant removing the bowl hose, for which I have a very rust free short pattern spanner  ..... that is still slippery!

The oil radiator was mounted like yours Miles, just behind the grille.  Hoses passed through the cardboard duct in MGB oil cooler hose grommets.

Peter W

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Miles move yours up against the rad and if it works I’ll do the same. 

I don’t have an oil temp gauge so a don’t know the effectiveness of the oil cooler. 

I may notice how the water / elec fan responds tho. 

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Peter

Sounds like you need to reinstall. Perhaps with modern fuels burning at higher temperatures, there is now a value in using an oil cooler.

Hamish

I am not convinced that placing one adjacent to a radiator provides the optimum solution. At least with some distance between the two, some cooler air gets mixed with that passing through the oil cooler which wouldn't otherwise happen. Also, if being adjacent to each other was optimal, I am sure that would have been the standard location over the years. Overall, I suspect the difference is minimal.

Any thoughts from the racers out there - or physicists?

Miles

Edited by MilesA

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I would guess that placing them together would minimise the turbulence that would otherwise occur in the space between, and would restrict airflow.

Pete

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I’ve wondered why an oil cooler is placed in front of the radiator, and not next to it on many cars.

Given the size of an oil cooler, compared  to the water-radiator, I assume the required capacity (kW) of the oil cooler is much lower, and although it will impact the  capacity of the water radiator, that is limited.

Waldi

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If the oil cooler is to be fitted in front of the rad it should be as tight as possible( without touching) due to air turbulence as mentioned above

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Thanks all. Interestingly, Mocal provide the following advice (and I think they should know):

In the case of the air to oil cooler, The oil cooler will only achieve results where a volume of air is passing through the fins. The amount of heat dissipated by radiation is negligible. In practice the most convenient position for the oil cooler is in front of the water radiator where a flow of air is guaranteed. Even in cases where the water cooling is marginal, placing the cooler in this position will have hardly any effect on water temperature. The sheer volume of air passing through the cooler ensures that the air is only heated a few degrees; not enough to affect the water radiator performance, and as the oil cooler is a more efficient device for extracting heat from the engine, the overall effect is helpful. However, where water cooling is marginal it is essential that the oil cooler be placed against the water radiator face, otherwise warmer air leaving the oil cooler will become turbulent on meeting air at ambient temperatures and will not pass through the water radiator. If placing of cooler and water radiator in close proximity is not possible then a duct of thin aluminium should be made to exclude the ambient air. 

I am sure a few here will not favour the duct idea given the potential for damaging the radiator in a shunt. 

Miles

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At last a use for that old yoga mat....could you not just make a thick foam gasket to fit between the oil rad and the water rad to act as a duct?  attach it with double sided tape and stick a couple together to get a good thickness. 

Alternatively window draught excluder would do the job if stacked to make a good thickness.

Peter W

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Peter

Sounds like the best use for a yoga mat! Who needs one anyway after spending half of yesterday on my back across the seats fiddling with the rats nest of wires under the dash? Another benefit of owning a TR!

Miles

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Optimum air capture occurs when the area of the radiator is greater than the mouth of the duct entrance. This ensures the air is trapped in  the duct and cannot swirl back out forwards. The taper needed is a few degrees. Think I  read it in a book by Costin.

like this extreme design of his:

image.png.453c7027e900957a781c6736cb06d3e7.png

Peter

image.png

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Thanks Miles. 

I can feel yet another job coming on.

and I’m sure I’ll pick  the wrong yoga mat to cut up Peter  

 

However I used these when fitting my elec rad fan to protect the rad core from the through tie mechanism. And the hardtop mounting brackets that he rear.

https://www.argos.co.uk/product/6006857?gclsrc=aw.ds&&cmpid=GS001&_$ja=tsid:59156|acid:444-797-0832|cid:596310901|agid:28594315165|tid:pla-336626794003|crid:95888244205|nw:g|rnd:13714984938093248076|dvc:m|adp:1o9|mt:|loc:1006648&gclid=EAIaIQobChMIvrDZmOKl4wIVoQvTCh2hBgLKEAQYCSABEgK29_D_BwE

 

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It seems to me that a greater gap between the small-sized oil cooler and the standard radiator ought to be more effective.  The reason being that ; with the oil cooler and water cooled radiator very close together - the air flow through the combination will have greater back pressure, and therefore the air flow will tend to flow around them ..following the path of least resistance.  Although this would be through the remaining exposed area of the radiator, the cooling effect through the oil-cooler would be less effective. 

Conversely with the oil cooler clearly forward of the water filled radiator ; the air stream will pass through the cooler, and then re-combine with the air flow around it to then pass more evenly through the water-filled radiator.  

If however the oil cooler and the water filled radiator were of the same area (albeit of different core thickness) and ducted ..then putting them close together would not be so detrimental. 

..so detrimental. ?   Only if the finned tubes / the core of the two were actually designed to work together for the air flow, would they be properly efficient.  As it is - I'm sure one,  being of different core configuration, density and fin design to the other, would inevitably obstruct the other from the full benefit of the air flow.  Hence., the combined back pressure would be greater than the sum of the two independent entities.   

I further agree wholeheartedly with Peter's reference to Costin (a quite brilliant Engineer in my opinion) that the tract ought to be designed to avoid back pressure at the point of ingress through the grille.  In my view the easiest way to achieve this is not to use the TR original ducting panels at all  (I know.. sacrilege)  but instead to effectively dam across the engine bay where the radiator is.   I learnt this back in '79 as protégé to Anthony Stevens working on the Cipher (see photo below).  Btw., Tony was formerly Chief Engine Designer and project planner for Rootes at the time of the Sunbeam Rapier and its contemporaries were faced with the new-fangled  'motorways' ..and many cars subsequent over-heating problems.

Cipher_June87_3a.jpg.65b9fd3745448459d8485791325a97ca.jpg

Purely coincidentally, I noted the same last Tuesday evening at a TSSC meeting where one of the members came in his MGBGT .  .

mgb-engine-bay-700x490.jpg

.

 

Edited by Bfg

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Ah, BFG (do you have a name?). The joy of the Forum; one question and multiple solutions!

I am no scientist but I am inclined to pay heed to the advice of the manufacturers of the oil coolers who have an interest in ensuring that their products work and do so in a way that does not adversely effect other components. Obviously what is lacking, is evidence from a controlled testing of the options. Just a bit surprised that those from the racing fraternity have not worked this one out based on their experience.

As ever though, the range of responses provide reasons for more tinkering with our cars.

In my case I suspect the cooler was placed close to the grille on the basis that that would provide optimum air flow to it. The potential flaw in this arrangement is that the modern grille with its wide bars blocks a considerable amount of incoming air (and crimping the bars is another job on the tinkering list!)!

Miles

 

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I have a couple of pictures of my grill when I first got the car in silver  and later in black after I had been messing !! I had a spare grill that came with the car and modified the tatty one, by closing up the “bars”

interestingly you can also see the oil cooler in the “black” picture. Quite raised as well as a few inches forward of the rad. I guess the ideal is vertically alongside the rad.  Like the Dave hogye race car (the Ali rad pic) his video here 

2615C004-AC5F-4B78-8439-962FB79392A1.png

47F15227-815C-464D-9966-1B1066686B73.jpeg

CF357B04-B211-4705-B6C8-7721B7EE6DF3.jpeg

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On 7/6/2019 at 5:26 PM, Tr4Deano said:

If the oil cooler is to be fitted in front of the rad it should be as tight as possible( without touching) due to air turbulence as mentioned above

this is the principal that was explained to me by cambridge motor sport .They fitted the coolers tight to the rear of the rad.Mine is at the rear of the rad and as low as poss to get air flow

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I suspect there is no one answer to the question of positioning because the air flow through the grille,  the design of the tract,  the size of the oil-cooler,  the low pressure (extracted air) flow from behind the radiator,  and the available space in front of the radiator ..and therefore the potential distance between an oil cooler and a radiator,  are all so influential.

I recognise that if an oil cooler were placed just three-inches in front of a radiator - then the air flow through the cooler would not have the opportunity to re-combine with the air flow around it. There would simply be turbulence.  

Conversely, if the oil cooler might possibly be placed three-foot ahead of the radiator,  then would that same company still best recommend placing their cooler tight to the radiator.?  I suspect not.  Therefore I might presume that the clear space between the two, together with the aforementioned other factors have cross over point regarding efficiency,  and of course that point will vary with both vehicle and engine speeds (assuming an engine-driven fan).     

In your original post,  you suggest there's 9" clearance between your cooler and the radiator.  I would suggest this is an unusually generous distance for most short-fronted modern or rally cars Mocal oil coolers are now most often fitted to. Therefore their statement might be generally correct to that collective, but not necessarily the better solution.

I'm no expert on racing but perhaps the TR works cars placed the oil cooler as far forward (away from the radiator) as they could ?

..Just a thought like.

.

Edited by Bfg

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RadiatorInletDiagram_RD.jpg

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So am I right in thinking that the 2 and 3 small mouth cars are better than the 3a and 4 wide mouth cars, for cooling air flow through the rad. 

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So many details from that film about the Doug Hoyge rebuild that I loved! Vertical to the side looks good, but behind a cut out in the lower apron behind where the front bumper gives a dedicated location for a cooler and is popular. Hamish's cooler is raised up, allowing air to flow under directly to the rad. And then Peter throws in the claimed value of a slightly angled vertical duct either side of the radiator.

Of course Bfg you are correct - ultimately, there is no one answer. Trial and error will find what each of feel is best for our cars - and that may be pretty subjective! I have a cunning plan formulating for my car but, as ever, time is at a premium.  Perhaps in need to be pushed into retirement too!

PS I stand to be corrected but my understanding was that the 2 and 3 were regarded as having a better cooling design and the cardboard shroud installed in 3As was a hastily devised post production solution to overheating in the early 3As because of the wide grille and large gaps allowing air to wander past the radiator. When I installed one in my car I noticed a reduction (but an incomplete one) in running temperatures. Perhaps a slightly angled duct around the radiator all the way to the grille would assist.

Miles

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I popped out to look at the oil cooler position in relation to the radiator only to see that it is wet 

so now looks like I have a small leak on the oil cooler. 

It either Miles it’s your fault for raising this. But more truthfully thank you for raising this so it made me have a closer look and find an issue that need addressing. 

 

DC532D7F-B954-45DA-9DFE-622328FB7951.jpeg

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You can never relax with a TR! Did you notice the position of Ed's cooler on his lovely red racing 3A?

 

 

 

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1 hour ago, MilesA said:

You can never relax with a TR! Did you notice the position of Ed's cooler on his lovely red racing 3A?

 

 

 

Yes below the grill I have seen some like that it’s a popular place in racers

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Interesting what was said about having the radiator duct angled from a short width to a large width at the radiator.  I have a costin designed bonnet in my midget and the configuration is just this.  However the duct has a gap to place the oil cooler next to the radiator..

On my tr6 I have the oil cooler tight against the front lower section of the water radiator 

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