ok so I kinda understand how a swirl pot works. But what makes a good swirl pot?
I've seen some really skinny ones where the in + out lets are positioned like it isn't going to do much swirling.
So if I was to make my own, how should it look?

Also someone pls explain the purpose of the header tank? Is it just for water expansion and to allow overflow water to drip back into?
Why does it need to be tapped to the bottom of the rad before the thermostat?

I would had thought a good swirl pot would be sufficient?

IMO header tank is more important than swirl pot.

The header tank includes pressurised air above the coolant. Since air is easily compressible, the pressure will be maintained as the coolant cools and contracts. With the standard overflow setup, coolant is expelled as it heats / expands then as the engine cools pressure is lost which can lead to boiling / cavitation / air bubbles.

The reason the bottom of the tank plumbs to the pump intake is that this is the lowest pressure point in the system which encourages circulation of air and coolant from the bleed points through the header tank.

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Hi,

the reason for the retourn line is you need a circle, air that escapes the engine (etc.) flow to the header which is (or should) be the highest point, that volume needs to get compensated
by water, you can use any point on the pump inlet side in the system (on my new engine i will use the throttle body heating retourn fitting in the stainless pipe)

thats the way you get air out of the engine every time, and theoretically you aren't in need of a pressure less reserve tank

greetz

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Interesting theory, does that mean you are not planning on using an expansion tank/swirl pot?

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Thanks for the explanation guys.
So with the header tanks I noticed that many people make their own.
What should a good header tank look like or need?
Im thinking a pressure cap at the top for filling up.
An outlet at the very bottom which feeds to the bottom rad hose before the thermostat.
2 bleed intakes. 1 from swirl pot and 1 from rad.
anything else?

Also should the header tank be positioned higher than the radiator?
How much water&coolant should it be filled up with? Volume? Size?
Should it be filled to the top?
Does this mean I can remove the overflow bottle by the radiator with this setup?

It should have a pressure cap on top.
It needs to be the highest point in the system.
It shouldn't be filled to the top as you want air above it to act as a 'spring'.
Volume wise, they generally seem to be about 2 or 3 litres and filled about 1/2 way when cold. Not done any sums, it's just what they normally seem to be.

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thank you nibbles.
Very informative info.
How about the 2 over flow pipes? Should they be below the tank water level or above?
Below to allow water to come back into the system when it cools?

Above water level to avoid airlock in the bleed pipes. Gravity will keep the system full of water as long as water level in tank is highest part of system.

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People have pretty much covered what needs to be done already, one thing I will add is to make you remove the pressure seal out of the coolant rad cap so coolant can permanently free fow to the header tank, I can dig you out some pics of my set up if ya like ?

Martin

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Yer some pics would be good to see

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sketch

Useful topic, and I know it has been covered before, here is a very useful thread with lots of pics and info:

viewtopic.php?f=13&t=1513&hilit=header+swirl

If you don't mind I'm going to piggyback this topic rather than start a new one to keep info in less locations! I am planning on installing a header and swirl pot system on my car shortly, but it will be slightly different to most as I plan on using a Ford Sierra RS500 intercooler and radiator. The rad on this system does not have a rad cap or overflow as it is designed to work with a header tank arrangement.

My question would be, if there is no air bleed at the top of the rad do I only need an air bleed from the top of the swirl pot (which is in the top rad pipe above radiator level)? So effectively I just need a header with one bleed connection and a larger return connection at the bottom?

This appears to be all thats happening in this ford setup diagram (although whithout a swirl pot, just a T of the top pipe:



Here are the coolers offered up on my spare parts car - you can clearly see the benefit to intercooler pipe length and accesibilty, only a single hard pipe would be needed hot and cold sides minimising joints and boost leak risks, also the weight would be lower and further back than most common set ups:

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Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now!

Heh Treacle - nice to see you floating about again.

Steve & I have mused over the RS500 IC/Rad setup many a time - unfortunately it is about 50mm too high for a ST185 (ST205 has greater height for rad/ic).

My thoughts were that whilst it may self bleed if you have enough height for the header tank I would want bleed nipples at the top of the end tanks (See Celica WRC car setup).

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You would certainly want some sort of bleed from the Rad IMO, preferably on the side where the flow comes from the bottom. The flow will encourage air to this side through the core. It would be worth getting an aluminum welder to weld a bleed outlet into the top of the end tank as the thermostat switch hole looks a wee bit low.

Otherwise, looks an excellent set up. I have seen a standard setup on a 600ish CC shopping car (may be daihatsu but can't remember) where the FMIC pipes went over the top of the rad making a simple, neat & effective installation. I have pondered doing something similar using oval or rectangular plumbing to reduce the height so I can just cut some of the bonnet webbing to get it through.
Have you got any info on height and width of the RS500 rad & interccoler so I can see if it's viable for a 185 with some cutting & shutting.

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Intercooler



Rad



I don't think height should be an issue if mounting in front of the front panel as per my fitting example. I tried fitting on the engine side of the front panel and it will fit on an ST205 but doesn't leave sufficient space for the fans, putting it infront means its a straightforward fit.

Also worth noting that all the original gearbox coolers etc can stay in their original positions with this set up, although the aircon has to go. You also have to remove the bonnet catch so bonnet pins are necessary.

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^^^Click the banner for my Black Treacle project thread ^^^

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Thanks Edd.

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