Thanks for the comment guys, always nice if other are thinking with you 8) Especially if it's not the usual thing you do every day
the cooling is designed on typical thermosyphon principal, having heat/vapour pouring from the top (as that obviously where is goes). will forced by natural pressure, to flow out the top outlet. the enrushing air will drop temp across the rad which changing coolant from vapour's form to liguid form, which heavier than air to sink back to the bottom. more pressure would be required to actually push water from bottom to top outlet
I think in terms of usual and common physics you are right Zia, but when transformed to the setup and use as a cooling system for a (race) car, propably other parameters will be encountered for.
It seems that the airpockets keep in the top of the rad with the current setup and are not properly vented out via the radcap pressure system to the coolant overflow. The system just isn't capable of doing this when the coolant is heated more than it was intended from factory. More airpockets are created and these also tend to "stick" in the topfloor of the radiator. But when the warm coolant gets from downwards in the radiator the airpockets will be decreased a good deal while travelling to the top; it will also benefit from the relatively slow speed of travel of the coolant, because of the issue you just mentioned yourself. Coolant will have more time to cool down, heatpockets will be less likely to maintain. The question is indeed will the standard waterpump be adequate to fullfill its role in this setup; this I don't know :?
The above is ofcourse a theory and I would be pleased to share other views on this subject.
My engine builder argued the above mentioned theory and it fitted and still fits in my view. Interesting point is that the Cosworth cooling system is build as above mentioned. Also I looked at the marvelous EVO's, and it seems there cooling system shares the same view; ie. cold water enters the thermostat (block) via the top of the radiator.
Thanks for your help here Andrew. I'll try to give the info you need, but in some I will not be able unfortunatley.
- core data - width height and thickness, material (ie aluminium, copper) and more specificly (only if you can get it: water passage diameter, fin pitch etc of that paticular core, do you have the manufacturers data?)
It's a full aluminium rad, 52mm thick, height 310mm, lenght 640mm. Water inlet and outlet is 32mm. The other I do not know unfortunately.
- vehicle data: is it mounted behind an intercooler? do you know what temp air exits the intercooler (the air on the outside of the intercooler i mean), is the car track use? ie what 'average' speed are you looking at
The rad is behind the intercooler, not completely, I think it "blocks"around 50%. Here a pic where it's a bit more visualized:
I don't have data of the inlet and outlet temps, there probably accessable via DTA, but I don't have that data now. I think it will be around (outlet temp of IC) 20degrees C depending on ambient air temp.
The car is more meant for trackuse than a daily driver, but will be driven in the weekends in normal traffic. I must say that in the area I live we don't have often traffic jams, outside business hours.
"Average" speed is difficult to say. I will try her on the highway and also in Germany on the Autobahn and will try to clock the 300km/h
hopefully :lol: Say average is around 80km/h...
- water flow rates: do you use the standard water pump? or an electric pump? if so do you have any flow data for the pump?
Yes, still use the standard water pump, allthough a new Nissan item. I don't have the flow data of this pump; I know it is quoted in the manual, maybe other guys can help here? My manual is with the car, at the tuners, far from me
Hope you can do some with the info I have at the moment. Hope to hear form your calculations. Thanks again for the helping hand here 8)
rgds
habib
