Need to get better cooling on the tvrolet....

[tvrolet]

Took the tvrolet for its first run (of any length) today. Just over 50 miles, and used half a tank. I make that less than 7mpg . The car that puts the car in carbon

Anyway, I've always had a problem with cooling, and this just made it more evident, as on its previous short thrashes and track jaunts I'd just be topping up the header tank. It's not that it's getting too hot (rarely shows above 90), but it almost seems a 'total loss' system. I came up with a fairly simple system as there's no heater (BTW it's a small block chevy)

There's no thermostat, but I've experimented with different sized restrictor plates, but that doesn't seem to make much difference. 'Thermostat' feeds a custom-made swirl tank at an angle; idea was to promote a swirl in the tank..

I have a real problem with clearance under the bonnet, so the top of the swirl tank is maybe half way up the thermostat housing. There's a small pipe from the top centre of the swirl tank to the top of the header tank...my theory is it should get any air out the system. There's a larger pipe from the bottom of the header tank to the swirl pot to give a head of water. But again, with the clearance issues the top of the thermostat housing is half way up the header tank.

Feed to the top of the radiator is from the bottom of the swirl tank; feed from the bottom of the radiator goes back to the water pump.

I pick up my water temperatues (Pi data logger, so pretty accurate) off the swirl tank.

So, as I said before, the temperature ranges from 75-90ish, so not too hot. But it blows water out the header tank until the tank is empty, and then some. This takes a fair few miles (or a long time), but none the less after a run once things have cooled the water level is maybe 1cm off the top of the manifold, so below the thermostat and a little down the swirl pot.

I guess this might be the 'natural' level, but I'd rather it was a bit higher.

Cap on header tank is rated at 150Kpa (so around 22PSI), but I've no idea if it's accurate. Will probably get a replacement cap just in case. Radiator bleeds water from the top vent, so there's no air in there either.

So, any ideas how to modify the system to keep some water in the header tank? I real surprised by the lack of coolant in the tank when things cool, as it's obvisously brim full and venting when the engine's hot. One thought I had was that the volume of the cooling system wasn't large enough, so if there is a natural air/water ratio to allow for expansion maybe the level I'm ending up with (with an empty header tank) is that ratio?

[tinker-27]

have you tried a catch tank from the header tank with a two way rad cap,i know its not a prefect answer but it might help returning the water to the system as it cools.

[350Matt]

Make sure that there's a bleed from the top of the rad or the highest point back to the header tank, and the header tank shouldn't be full when cold as you need an air gap 1-2" to allow the water to expand

Best of luck

Matt

[DavidY]

Years ago I ran a TVR with a modded engine, and I initially had the same issue. In the end I put two expansion tanks in series (I think the same as your 'header' tank), this kept a greater volume of water in the system. You might have to do a bit of experimentation with pressure cap values though (or use one blank and one pressure cap).

But if the level always settles down to the same point (and doesn't drop lower on subsequent journeys) and does get pumped round, then Ipersonally wouldn't worry too much.

But try either increasing the size of your header (expension) tank or put two in series, the latter is obviously easy to try.

davidy

[Speed eight]

Hello tvrolet.
The cooling system fundamentals as you have them are one form of being correct.
There are other far less complicated ways, they way mine is for example.
Having said that your temperature range is correct also. The optimum temperature for a SBC being 80 degrees running temperature.

I do not at this point see that the level of water that you end up with in your swirl pot after your run is of any consequence. Let me clarify that point.
If this level of water is reached and after cooling the car is then run again and there is no further loss of water or any overheating problems, then all is well.

If water should continue to be lost from the system from a restart after the first run .............

Assuming that you have no water leakage from an external point and that the pressure cap is not "lifting" before it should do, then you will have to investigate an internal possible problem. Such as head gasket leakage and the associated result from that position.

Regards,
Speedeight

[GreenV8S]

Some thoughts:

Fit a thermostat. Take out the restrictor plate and fit a thermostat with a decent bypass.

The basic layout seems OK but you need to ensure that the header tank has enough air volume to cope with expansion within the system. I would say that 1L of air is a minimum and if you can get 2L worth so much the better. The header tank should always have some water in it - if it ever goes completely empty while the engine is running (even transiently) you know it's too small.

Full flow swirl pots are OK in principle but need to be big enough. You need plenty of height, and you need to make sure that there is a stagnant volume above the inlet. One problem you may suffer from is that if the header tank is too small the system will pull air into the swirl tank. Instead of acting like a separator the swirl tank then acts like an aerator, and you will get entrained bubbles pulled out the bottom into the radiator. Since you don't have a degas line for the radiator, any bubbles that enter the radiator will tend to settle out in the top tank and will stay there until you switch off the engine. Hence it will continually spit water out and eventually you will end up with a radiator full of air.

What I would suggest you do is fit a remote stat (Landrover PEM101020 is an entry stat that has a full flow bypass), if possible fit a degas line from the top of the rad to the input to the swirl tank. Basically you want to provide a route for air to go from the top of the engine, and the top of the radiator, up to the pressure cap, without having to go downhill at any point and without having to go against the normal direction of flow.

I'd prefer to see the swirl tank replaced with one that is in parallel with the radiator rather than in series with it if possible, but the system as it stands isn't fundamentally wrong and can be made to work OK.

Edited by GreenV8S on Sunday 7th October 13:44

[Pete500]

Hi, have you connected the small (5-6mm) water outlets from the heads? Must connect to pump suction side on LS2 to evacuate eventually trapped air. I used a standard TVR setup on mine, swirl pot etc and an original LS2 termostat. The termostat is fed with the return water from the rad, this is GM normal and will give a more stable temeperature. I used some time to get rid of all trapped air in the coolant system, this will look like it uses water, but after this I have done 3000miles without adding any water. pt

[scooterscot]

Looking at your diagram it would help to have the water feed pipe from the header tank feeding in much lower in the swirl pot. from your diagram it would appear that you could be drawing some air into the system from the header tank when there is a lot of flow through the swirl pot. Any air in the engine will soon force out the coolant as it has a much greater rate of expansion. The other thought has to be do you have a small cylinder head gasket leak. The most important basic principle is, any water being introduced must be free of air.

[scooterscot]

Another thought your drawing shows the air bleed to be lower than the highest piont in the system,you need to bleed the air from the highest piont.Saw a race car cured after many weeks of trying and the air bleed was only 9mm below the highest piont.