Combined swirlpot and expansion tank
Discussion
So which cap goes where? 
When my S came back from the garage having had heads replaced my mechanic had removed the expansion tank as it was "a pointless irritation" .
I was a bit suprised, but the man knows his TVR's having worked on one of the race teams in the past, and also for one of the major dealers.
Thoughts?
I was a bit suprised, but the man knows his TVR's having worked on one of the race teams in the past, and also for one of the major dealers.
Thoughts?
catretriever said:
When my S came back from the garage having had heads replaced my mechanic had removed the expansion tank as it was "a pointless irritation" .
I was a bit suprised, but the man knows his TVR's having worked on one of the race teams in the past, and also for one of the major dealers.
Thoughts?
It's not pointless if the caps are on the correct way and there is a TVR bulletin that outlines which way they should go. I am not going there today.I was a bit suprised, but the man knows his TVR's having worked on one of the race teams in the past, and also for one of the major dealers.
Thoughts?
I have been on 3 Eurotours in very high temperature and each time noted the expansion tank had a greater volume of water when the engine was hot and that the level dropped once the engine had cooled and pulled the water back into the SP. Without the expansion tank, the water would have been lost, necessitating the topping up of the SP.
Oldred_V8S said:
I have been on 3 Eurotours in very high temperature and each time noted the expansion tank had a greater volume of water when the engine was hot and that the level dropped once the engine had cooled and pulled the water back into the SP. Without the expansion tank, the water would have been lost, necessitating the topping up of the SP.
Yes, but..... it's the "same bit of water" that gets blown out and sucked back, if you see what I mean?So why would it not work if system full at cold, heats up and expands, excess blown out, no expansion or catch tank so as system cools air is drawn in. Next time engine heats up there is room for the water to expand so nothing blown out, everybody happy
Oldred_V8S said:
...It's not pointless if the caps are on the correct way and there is a TVR bulletin that outlines which way they should go. I am not going there today.....
I'll save you the trouble Paul; HEREIf Shaun is making your's using the drawings I sent him for mine the capacity will be near-as-dam-it 1000ml. That means that if you half fill the expansion tank (easy with his neat sight tube addition) you will have 500cc of expansion room which should, in theory, mean that you will have the ideal balance between surplus coolant to flow back into the system when it cools and sufficient room for expansion when hot and so avoid any blowing out the top tube.
v8s4me said:
Oldred_V8S said:
...It's not pointless if the caps are on the correct way and there is a TVR bulletin that outlines which way they should go. I am not going there today.....
I'll save you the trouble Paul; HEREIf Shaun is making your's using the drawings I sent him for mine the capacity will be near-as-dam-it 1000ml. That means that if you half fill the expansion tank (easy with his neat sight tube addition) you will have 500cc of expansion room which should, in theory, mean that you will have the ideal balance between surplus coolant to flow back into the system when it cools and sufficient room for expansion when hot and so avoid any blowing out the top tube.
Shaun has made me one, it is mine detailed in this thread. I requested the sight tube as the old mincies aren't what they once were, especially down the dark end of the engine. From the pictures, it looks like Shaun has done an excellent job of deciphering my drawings, just need the courier to drop it off now.
phillpot said:
Oldred_V8S said:
I have been on 3 Eurotours in very high temperature and each time noted the expansion tank had a greater volume of water when the engine was hot and that the level dropped once the engine had cooled and pulled the water back into the SP. Without the expansion tank, the water would have been lost, necessitating the topping up of the SP.
Yes, but..... it's the "same bit of water" that gets blown out and sucked back, if you see what I mean?So why would it not work if system full at cold, heats up and expands, excess blown out, no expansion or catch tank so as system cools air is drawn in. Next time engine heats up there is room for the water to expand so nothing blown out, everybody happy
I agree 100%, I was referring to what would happen if the expansion tank were not there. I realise it is the same bit of water getting sucked back and forth, but without the tank the water would have been vented to the atmosphere and lost, leaving the water in the SP at a lower level (once cooled) and maybe the possibility of air entering the rest of the cooling system. At least with an expansion tank one has the comfort of knowing there is a reservoir of water that will be pulled back into the cooling system in the event of a coolant loss, plus it is easier to check the presence of water in the system.
Hi Mike and Paul, not sure I want get into this again but.....!!!!
Instead of considering the swirl pot and expansion tanks as two separate tanks perhaps we should consider them as one as that is how they function as far as thermodynamics is concerned if the pressure cap is on the expansion tank. All the expansion tank is doing is to provide a head of compressible air over the water sufficient to allow the water to expand. Now the clever bit would to get that volume of air to the optimum size to keep the system from rising above the optimum level or pressurisation, whatever that is!
Technically that should be possible in a single combined chamber.
As I understand it the swirl pot(which is a bit of a misnomer anyway) is there to allow air to escape from the almost boiling water from the heads, which would not be a requirement if the rad was higher than the heads as in most cars. So the air chamber must be above the water in the heads (either physically above it in the swirl pot or accessed as at present through a pipe from the top of the swirlpot, which has the same effect).
But whether arranging this in a single tank would be convenient or a better arrangement in this particular engine bay I am not sure.
As far as doing away with the expansion tank goes, that should be fine if the cooling system is all in good order but surely it must risk increasing the water pressure to higher levels than they would be with the expansion tank. Thermodynamics says the water will not boil until higher temperatures so that might be OK but surely most overheating problems arise from a loss of pressure/water due to a mechanical leak problem of some sort.
I have been thinking 'out loud', which is always dangerous!! So, as they say at the end of any 6th form or college idea:
Discuss!!!
Instead of considering the swirl pot and expansion tanks as two separate tanks perhaps we should consider them as one as that is how they function as far as thermodynamics is concerned if the pressure cap is on the expansion tank. All the expansion tank is doing is to provide a head of compressible air over the water sufficient to allow the water to expand. Now the clever bit would to get that volume of air to the optimum size to keep the system from rising above the optimum level or pressurisation, whatever that is!
Technically that should be possible in a single combined chamber.
As I understand it the swirl pot(which is a bit of a misnomer anyway) is there to allow air to escape from the almost boiling water from the heads, which would not be a requirement if the rad was higher than the heads as in most cars. So the air chamber must be above the water in the heads (either physically above it in the swirl pot or accessed as at present through a pipe from the top of the swirlpot, which has the same effect).
But whether arranging this in a single tank would be convenient or a better arrangement in this particular engine bay I am not sure.
As far as doing away with the expansion tank goes, that should be fine if the cooling system is all in good order but surely it must risk increasing the water pressure to higher levels than they would be with the expansion tank. Thermodynamics says the water will not boil until higher temperatures so that might be OK but surely most overheating problems arise from a loss of pressure/water due to a mechanical leak problem of some sort.
I have been thinking 'out loud', which is always dangerous!! So, as they say at the end of any 6th form or college idea:
Discuss!!!
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