Samuelle |
13th December 2010 21:21 |
Quote:
Originally Posted by BigRuss
(Post 634005)
I had certain reservations when I saw the stat fitted to Phil's car yesterday, although I was impressed with the ease of fitting, the look and quality of the stat housing and the neatness of how it fitted, I did wonder about it's suitability in controlling the temperature correctly.
Firstly there will be approx 10-15C difference in the temperature between the engine water jacket temperature (measured by the IPK/Scanguage) and the actual temperature in the top hose. (Add a second digital temp sensor/guage into the top hose and you'll see ;) if you watch the two guages together you'll see exactly what goes on in the cooling system under all load conditions)
Another thing to consider would be the cooling effect of the airflow through the radiator hitting the alloy casing of the thermostat housing but suspect this would only be a small amount and with the car moving.
Looking at the original design the stat is fitted to the return, this will restrict the flow through the radiator then will allow an amount of cooled coolant into the engine before it shuts again. Fitting a stat to the outlet will allow a bigger slug of cooled coolant to be drawn into the engine before it's shut off by the thermostat (basically it will over-cool).
It may be better to locate the themostat into the return, it's something that needs a little more thought and ideally some accurate temperature readings need to be taken, but I'm sure a perfect solution cannot be far away.
Russ
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I think you may be being a bit over cautious here. The bottome line is the temperature of the engine block rather than the temp of the coolant. The thermostats don't operate that acurately anyway, with a fairly large leway built into the system, and that is of course if you have an operating thermostat in the first place, which a lot of people don't. The thermostat mod is fitted just after the coolant exits the block IIRC, and I find it hard to beleive that there would be a 10-15C difference in this short distance. My previous car was a BMW E12, and on the excellent 'first fives' board there were some yanks who raced in some kind of classic class. some of them fitted second temp sensors to the top tube, and IIRC I don't recall any of them talking about a big temerature difference between the two sensors.
As to the extra slug of coolant you mention, I don't see what difference it would make if the thermostat is closing flow at the exit or inlet point. Surely either way it is going to stop flow? or am I missing something here? If I am missing something, and there would be an extra slug of cooler coolant, how much difference would that make to the temperature of the block anyway (as opposed to the temperature of the coolant)?
As to fitting the second therm to the inlet rather than the exit hose? Wouldn't the temp of the coolant just after it exits the block be closer to the temp of the standard therm that is integral to the block, than if it was fitted to a hose after the radiator but before the engine block?
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