Rad, swirl pots et al

HolyCount

New member
Just discovered that, due to trying to fit a mini engine where a VW air cooled lump is supposed to go, the radiator will be lower than the engine. So,I need a crash course in cooling systems !!!!

The cap on the Mini rad would need to be blanked and another method of filling arranged, which is where, I am told,  a swirl pot comes in to play, it solves the problem of filling the system, and allows the rad to be mounted lower than the motor without any air locks, plus, apparently I need the stat housing from a 1300 Maestro which turns the outlet round the other way. Have never considered swirlpots for the cooling system and know VERY little about them (in fact all I know is already in this post).

It has been suggested that I replace the mini rad with one from a Mk 2 Metro ---- any ideas why ????

Can anybody enlighten me ?
 

Phaeton

Moderator
Staff member
Not me other than I have sealed off my Mini rad & put an expansion bottle in the heater flow/return, now whether that is a swirl pot I don't know.

Alan...
 

esdebe

New member
a swirl pot could be used in the same way as an expansion tank, so you could go the same sort of setup as Alan has.  To blank off the standard mini rad you can just buy a non pressure released cap, this seals the filler however the normal overflow outlet on the filler neck will be left open on this needs to be connected to the swirl pot / expansion tank or get blocked off  (blocking it off can lead to an airlock unless you remove the blanking cap while filling up the swirl pot / expansion tank.

Swirl pots / header tanks would normal have multiple connectors on them, the one at the top would have the mini rad over flow go into it, the one closest to the bottom would have connect back into the mini plumbing, usually on the heater matrix take off side of the mini head.  It would be recommend that where ever you plumb it back in it is on the hot side of a radiator so that the water in it can be cooled before returning to the engine.

Simon
 

jason_l

New member
Where you placing the rad then Kev? Im guessing its sort of infront of the engine, behind the front wheel?

Might be worth looking at the fiat chinqy rad that i have on my buggy. It has a in/out for the coolant pipes and a port for a thermostatic fan switch but has no filler piont on it at all.

My set up has the rad mounted at the front and then the fill piont is alot further back at the top of the system. I don't have a swirl pot but just a in line filler piont. Im not sure if i need a swirl pot but might be a good idea i guess as its going to be a bit fiddly trying to fill it up. and gives me the chance to make another custom piece  ;D

Jason :D
 

Angel Boy

New member
I've not heard of a swirl pot been used in this manner before.  I'm more use to or associate the use of swirl pots in relation to fuel systems as they are used to stop fuel pump starvation and injectors running dry etc.  Header tanks are a term I would normally associate with what you are talking about.  Swirl pots tend not to have a point of filling which is what a header tank tends to have.

Have a look here for swirl pots: http://www.fortunecity.com/silverstone/impala/1012/cars/tech/swirl/swirlfaq.html

What you are trying to replicate almost is your central heating system.  You have a radiator, a pump, a thermostat, something to heat the water (the engine in this case) and some means of topping the system up, in this case the header tank is the point of entry.  If you look in the engine bay of a modern eurobox, you'll see some form of plastic tank with a cap on which is the point you'll fill up.  You'll also notice that it is the highest point in the cooling system this is important.  From the plastic tank with the cap on the (header tank) you'll normally find to hoses, a big one and a little one.  The bigger of the two is the point of entry of the water into the cooling system.  The other is the pressure relief in the system, a bit like the escape to the road pipe that comes out of the top of the Mini rad that we feed into a plastic bottle so we don't loose to much coolant etc.  In this case it cycles back into the header to be fed back into the system.  The cap on the header tank is pressurised if the pressure gets too much then it will just vent to atmosphere with no means of catching it.  So the reason why the height of the header tank is important is that if it is lower then the highest point then it is likely to try air in the system and result in locks and stop the flow of coolant around the system.  The idea is that if the header is the highest point the air has a place to escape to.  My experience in this is that all very well and good, but if you have a longish run of hose then it is wise to install some form of bleed valve on it to assist with getting rid of the air so you can get maximum efficiency from the system.

Hope you are still with me on this......!

If you want to keep with you Mini rad then you'll need a blanking cap as mentioned, a header tank, a t-piece and decide on which side of the pump you want the header tank to feed into.  I think it is the inlet side of the pump and not the outlet (someone set me right here as I've not had to think about this in a while).  It might be easier to do as Jason has done and ditch the Mini rad and get something that will fit the space you have rather then adapt around the Mini rad.

Here are some examples of header tanks that you can fit with the Mini system: http://shop1.actinicexpress.co.uk/shops/Rat_Sport/index.php?cat=Radiator_Expansion_Tank___Swirl_Pot

Hope this all helps.  Ask away if you have any more questions and if anyone disagrees with me by all means say so.  I'm there to be shot down (it's my day job so I'm use to it).

Andy
 

HolyCount

New member
Many thanks for that Andy ---- the central heating system is a good analogy.  Thanks for that link to Ratsport ---- some lovely looking kit there  ;D  Better not let Jason see!!!!!  ::)

Am bidding on a metro rad at the mo ---wider  than the mini item, but shorter too ( which is the main constraint).

All coming together a bit at a time  ;D ;D
 

HolyCount

New member
Been looking into cooling system swirl pots and found this nugget:

What does the swirl pot do?


It is standard race car practice to use a swirl pot in the cooling system. If hot spots in the engine cause localised boiling of the water, small pockets of air will form. Air in the water will reduce the heat transference properties of the cooling system. If correctly positioned & designed, the swirl pot will spin the water around inside it, making any water pockets form in the middle of the water. Percolation will then make this air rise inside the swirl pot, and exit out of the small bleed tube in the top, back to the header tank.

And, from the guy making the original suggestion:

.......Which allows rad to be mounted lower than the motor with out getting airlock problems.
I have to admit I have as often as not just made one by just cutting the neck off a scrap radiator and welding a few bits of tube together, ...........
It also means that then because the pressure cap is fitted to the top of the swirl pot, the expansion tank is not pressurised and therefore need not be anything special, and can be fitted lower than the swirl pot for easy filling.   

looks like this

  http://www.conceptracing.co.uk/gallery/ ... .jpg                   
 

jason_l

New member
HolyCount":1c6vcwcn said:
Better not let Jason see!!!!!   ::)

What you trying to say  :D and anyway i have already seen that site LOL was going to get my fuel tank from there originally until i decided to make it from scratch.

Looking good Kev anyway, looks like your properly looking into this.

I will be considering a swirl pot now then as well. My current coolant fill piont is very close to the thermostat housing and my rad is lower than my engine so may cause problems? Gives me another thing to make from scratch  ;D
 

HolyCount

New member
jason_l":3hshxpnz said:
Looking good Kev anyway, looks like your properly looking into this.

To be honest water swirl pots had never even entered my tiny mind before, but with the cooling issues rear mounted A series engines have, it can only help.

All I was going to do was wack an A series where the aircooled went and "robert's your father's brother" ..... now the cooling system is being modified with a metro rad and swirl pot and meastro stat housing ( to point t'other way), and I am seriously considering popping on a 3 branch manifold instead of the stock item, to give me three pipes rearward. Added to that the alternator has been dumped in favour of a 2CV item ( fits better the wrong way round). Why are these things never as straighforward as you think they'll be ???
 

Angel Boy

New member
HolyCount":270ozk06 said:
Been looking into cooling system swirl pots and found this nugget:

What does the swirl pot do?


It is standard race car practice to use a swirl pot in the cooling system. If hot spots in the engine cause localised boiling of the water, small pockets of air will form. Air in the water will reduce the heat transference properties of the cooling system. If correctly positioned & designed, the swirl pot will spin the water around inside it, making any water pockets form in the middle of the water. Percolation will then make this air rise inside the swirl pot, and exit out of the small bleed tube in the top, back to the header tank.

And, from the guy making the original suggestion:

.......Which allows rad to be mounted lower than the motor with out getting airlock problems.
I have to admit I have as often as not just made one by just cutting the neck off a scrap radiator and welding a few bits of tube together, ...........
It also means that then because the pressure cap is fitted to the top of the swirl pot, the expansion tank is not pressurised and therefore need not be anything special, and can be fitted lower than the swirl pot for easy filling.   

looks like this

   http://www.conceptracing.co.uk/gallery/001_general/014_water_swirl_pot_1.jpg                   

Well I've never heard of it before, but now I've read your text, everyday is a learning day!  I can see the principle of it and it is all trying to get rid of air pockets that can be generated in the system to reduce the potential of hotspots.  Sounds like you have a plan and in my re-jigged rad at the front etc it looks like I might have to fit one as well  ;D

Cool, great discussion.

Andy
 

HolyCount

New member
Just to continue this thread ( although non buggy, still mini engine) thought you might like to see the fabricated swirl pot. I am afraid it's not all shiny alloy like Jason would make, cos my bits are going to be hiden under the body, so I am saving the bit of bling for the outside  8)



The long pipe isn't obligatory, but just saves having more joins in pipes.
 

jason_l

New member
Looking good Kev  ;D I am leaving a swirl pot off but if there are issues i may add one later?

I don't polish everything, just the parts on show, problem is almost everything is on show  :( :D

Jason :D
 

HolyCount

New member
jason_l":1i2mfy37 said:
Looking good Kev  ;D I am leaving a swirl pot off but if there are issues i may add one later?

I don't polish everything, just the parts on show, problem is almost everything is on show  :( :D

Jason :D

Yep -- the joys of the freestyle -- everything on show  ;D  All my bits are hidden away -- even so I will still give it all a clean and a coat of paint (well .... that's the plan  ::)
 
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