header tank for ej20t bug

MostlyMonki · Posted: Mon May 19, 2008 2:31 pm Post subject: header tank for ej20t bug

at the moment I've just got the stock impreza header tank, although I've moved the bracket so it sits slightly higher and more central on the engine (due to clearence problems with the decklid).

i see most people get rid of the stock one and use a different/bigger tank, but i dont know why?? is there any reason that i couldnt just keep the stock one?
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'72 Ratty Bug - Subaru EJ20 Turbo motor.

Ianbott · Posted: Mon May 19, 2008 5:40 pm Post subject:

Maybe due to the incerease in water volume gained by extending the rad pipes to the front of the car (more water = more expansion)
I may be a million miles away.
Cheers Ian.

ricola · Posted: Mon May 19, 2008 6:40 pm Post subject:

The increase in volume of the system is the main one. However, the subaru system uses an overflow design, there is an overflow tank normally mounted to the radiator. The enclosed system only has a very small volume of air to expand into and the system is designed to overflow into this extra reservoir, when the coolant cools/contracts the coolant is sucked back into the system. I'm not really sure on the technical reasons Subaru did this, maybe lack of space? I'll be fitting one bigger coolant tank so I can easily check the system volume and also I can't help feeling that coolant must evaporate out of the standard expansion tank over time requiring more frequent top ups...
Rich
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http://www.ricola.co.uk