Cooling - Fans and PoloRads?
dhutch - 18/1/12 at 08:48 AM
I need to the the westfield back on the road and to do that I need to replumb the cooling which came off amoungst other things because the larger
copper radiator and small fan behind where causing cooling issues in stop-start conditions ie traffic in hot weather, which when lost in paris is not
a helpfull addition!
- Also, all the hoses are rottern, the rad weeps, and i want to reduce the huge mass on the front end.
Lots of people here are using polo rads, which i bought on of (uses) but its the 15mm core one where most use the thicker core. Is this radiator large
enough for a mildly tuned 2ltr engine idling at 1500ish? Or as I can fit it, should i looke at a slightly larger one?
Also, for standstill clearly the fan is also critical. Can anyone recomend a twin speed fan? I can fit a fan switch in both the thermostat housing and
proberbly the radiator (certainly if i go polorad) as well as manual a switch.
Daniel
whitestu - 18/1/12 at 09:25 AM
This is the one most people use: Link
Not sure what thickness it is. but you should be able to cross reference the part number to the one you bought.
As for fans I just used the old Sierra one on my 2.0 Zetec installation. The Polo rad has plenty of capacity so it shouldn't need much of a fan
to keep it cool.
1500 rpm is a high tickover for a standard engine though.
Stu
britishtrident - 18/1/12 at 11:30 AM
To make a 2 speed fan all you need is a resistor of 1 or 2 ohms with a high enough power rating, depending on the fan size 25 to 75 watts
should be high enough enough for anything that will fit under the nose of your car. You can make the resistance up by putting separate
resistances in series or parallel, for example two 3.3 ohm 50 watt resistors in parallel.
see this ebay link Range of Aluminium Clad Wirewound Resistors 5w - 50w 0.05 - 3.3k Ohm | eBay
Polo fan switches are M22 thread and a wide variety of switching temperatures are available including 2 speed versions.
If you drill a couple of small holes in the thermostat valve plate then the thermostat will respond faster to changes in engine temperature.
You should have a by-pass connection ie water should still circulate round the engine even if thermostat is closed and the heater turned is
off.
paulf - 18/1/12 at 09:20 PM
I have a polo rad and 2 fire blade fans fitted to it, the rad has a dual temp switch and one fan is connected to the lower temp switch , the second
fan is connected to the higher temp switch and the dash override switch.Usually only the first fan comes on but if stuck in heavy traffic I can switch
in the 2nd fan or wait for the 2nd temp switch to bring it on.It seems to work well even though the polo rad I have is a brass cored one and maybe not
as efficient as an alloy one.
Paul
Neville Jones - 19/1/12 at 12:17 PM
Depending on the switch, that second fan will only switch on at well above 100c. Not too good. They are the temps I have measured and verified.
Cheers,
Nev.
dhutch - 20/1/12 at 11:09 AM
quote:
The Polo rad has plenty of capacity so it shouldn't need much of a fan to keep it cool.
1500 rpm is a high tickover for a standard engine though.
Thats reassuing. Dont want to replace the current one and find im little better off.
The idle is a little high, partly to help it maintain idle when not upto temp (no choke cable fitted), partly becauase the little race battery
struggles when the engine hot so stalling isnt clever, partly because its on a slightly lump cam, and partly becuase im being a bit lazy sorting out
all the above issues and adding half a turn is a easy if dirty fix!
quote:
Originally posted by Neville Jones
Depending on the switch, that second fan will only switch on at well above 100c. Not too good.
I noticed this too which was going to be my next question, one of the reasons why i was looking at two single switches, I very much like having a
manual switch for when you know its going to get hot, but also want an automated solution incase i forget!
quote:
Originally posted by britishtrident
To make a 2 speed fan all you need is a resistor of 1 or 2 ohms with a high enough power rating.
This cant be what most two-speed fans do is it? Obviously it would work if you started out with a powerfull enough fan, but I always assumed two-speed
fans have twin windings or something?
Daniel
loggyboy - 20/1/12 at 11:19 AM
I cant see much point in a 2 speed. The thermostat will decide if the engine needs cooling or not, why does the fan need to help - seems to be overly
complicated for little or no gain.
paulf - 20/1/12 at 11:30 AM
Agreed but as I had 2 bike fans and they fitted on neatly I decided to fit them in this layout.It is not really necessary if a single large fan is
fitted but seems to work well as a 2 fan system on my car.If starting from scratch i would just use a polo rad and single 10 or 12 inch fan to suit
wired into the temp sender in rad and a manual override just in case as its easy to fit.
Paul
quote:
Originally posted by loggyboy
I cant see much point in a 2 speed. The thermostat will decide if the engine needs cooling or not, why does the fan need to help - seems to be overly
complicated for little or no gain.
dhutch - 29/1/12 at 01:08 PM
quote:
Originally posted by loggyboy
I cant see much point in a 2 speed. The thermostat will decide if the engine needs cooling or not, why does the fan need to help - seems to be overly
complicated for little or no gain.
Obviously it does at an amount more complication but it means you can a seriously powerful fan for max
cooling, without having to have a tornado kick in when a gentle fan is all thats required.
Daniel