Following on from my electric pump thread, I'd be interested to know what diameter pipes are being used from engine to radiator.

32mm id ally for 5.0l v8 no problems

I'm using 1.25" Alum. for my main pipes...around 32mm



Water pipes

[Edited on 1/7/10 by Alan B]

32mm aerial pole from B&Q

28mm mains water copper tube on my front engined/rear radiatored car, easy to work and can have hard soldered joints and bends easily

Thanks Chaps. I probably should have gone larger but difficult to change at this stage.

CNHSS1 is using 28mm copper the same as I am so a couple of quick questions for you if I may;

1 What engine and rad are you using?
2 Are you using the standard water pump or electric?
3 What is the running temperature?
4 Are you using the standard thermostat or a remote one fitted into the bottom hose?

Thanks for your help.

+1 ON THE AERIAL POLE FROM B&Q

caps lock dam it

[Edited on 1/7/10 by afj]

To check if the system can transfer enough heat to the radiator using the current pump and pipe, perform this (free) test. Remove the thermostat completely. Run the engine. If the engine still runs too hot, you are not getting enough flow round the coolant loop. If it runs cold you need a better thermostat.

Domestic plumbing systems calc a 28mm pipe should allow 40Kw of heat transfer into rooms at 20DegC from water at 70DegC (if your radiatros are big enough). ETA I thinks thats actually limited by the boiler to pipe transfer though as the temperature differrence there will be least.

Regards
Hugh

[Edited on 1/7/10 by hughpinder]

Thanks Hugh. Do you think the thermostat is impeding the water flow or that it opens at a too high a temperature? I'm currently using an 82 degree thermostat in place of the 89 one that was in originally. The engine still gets up to the same temperature but it just takes longer to get there.

Can you clarify how your para 2 relates to an engine situation.

Thank you.

I think the thermostat is restricting flow. Removing it will prove weather this is the case or not. Obviously if the temperature tops out at (say) 70 degrees with no stat in you may be able to get a stat that allows more flow to pass. If not, a higher pressure pump will push more water through the restriction.

What size are the inlets and outlets on the radiator? - theres little point in replaceing the pipes if the pipe diameter is already as big as the radiator inlet.

The second paragraph just gives an indication of how much heat you can pass down a 28mm pipe.

Regards
Hugh

Thank you Hugh, The radiator stubs are for 32mm rubber hose. I'm reducing down to 28mm copper through the car and then back to 32mm rubber hoses to connect onto the engine. At this stage, it would be a major redesign to put in larger diameter pipes and I'd really not want to contemplate that! I'll certainly try running without a thermostat and see if that makes any difference so thank you for that suggestion.

I'm also going to do a comparison running in 4th gear against 5th because higher revs will increase pumping speed. If running in 4th drops the temperature then that will show that it is a question of flow and that an electric pump will be the answer.

Sounds like a good plan

Hugh

er, i'd really go with the diameter of the connections on your engine and radiator. thats where i'd start
mine are 35mm on the engine, 38mm on the radiator, so 35mm pipes, and 38 to 35mm reducers on the radiator

quote:

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Originally posted by blakep82
er, i'd really go with the diameter of the connections on your engine and radiator. thats where i'd start
mine are 35mm on the engine, 38mm on the radiator, so 35mm pipes, and 38 to 35mm reducers on the radiator

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blakep82 and Alan B, you are quite right to be scathing and in retrospect I would have done the same. However, the reason I went for 28mm copper was that it fits inside the car under the seats so space is restricted and I can bend it. I have no means of bending larger sections. I had hoped that 28mm tube would have been adequate.

quote:

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Originally posted by 2cv
blakep82 and Alan B, you are quite right to be scathing and in retrospect I would have done the same. However, the reason I went for 28mm copper was that it fits inside the car under the seats so space is restricted and I can bend it. I have no means of bending larger sections. I had hoped that 28mm tube would have been adequate.

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quote: I can't speak for Blake of course, but there was no scathing intended from me....just a very simplistic approach, which may or not be correct......whatever works...works....simples..

Thanks Alan. you only pointed out what I already deep down knew that it wasn't the best decision in the world to reduce the diameter of the makers design particularly in view of the length of the pipes.

However, all is well and the problem was not one of water flow but getting the air out from under the bonnet. Running without the bonnet produced a much lower and very stable running temperature so, quite a relief really.