02GF74
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| posted on 12/1/10 at 11:23 AM |
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radiator fan cooling switch temps?
I used to have a Kenlowe type bulb type temperature sensor with a temperatruse adjuster but I am loathe to drill my new alloy radiator.
My engine is 1600 crossflow, standard 88 C thermostat.
I am looking to fit a intermotor fan switch that has 2 contacts, some possiblities:
88-83 / 92-87 (on-off temps).
92-87/97-92
93-88/97-92
So just trying to guage opinion of what temperature your fan kicks in and goes off.
I don't want the fan running all the time so I reckon that the temperaturs it turns must be greater than the thermostat? hence rules out the
first one.
In case you are worndering why 2 contacts? I intent to have 2 fans, the second one kicks in when the higher temp second switch closes or
alternatively at lowere temp, fans run in series = slower speed but at higher temp, run in parallel - faster. Might be an unnecessary complication so
I may end up using since contact switch.
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DIY Si
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| posted on 12/1/10 at 11:31 AM |
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I'd go with the highest of you settings, although even then I'd set a fan slightly higher than that, maybe so that the second fan comes in
at 100-103C. A lot of kit cars seems to be almost over cooled at times. Mine has a huge fan with a manual switch and it only ever gets switched on it
traffic in summer.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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02GF74
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| posted on 12/1/10 at 11:42 AM |
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other options: (both single and double contact)
Part No. Temp °C
50100 82-68
50101 84-79/88-83
50250 86-76
50012 86-77
50090 86-81
50120 88-79
50091 88-83 / 92-87
50296 88-79/110-102
50271 88-83
50217 88-83/92-87
50240 90-80
50113 92-82/95-80
50170 92-87
50215 92-87/97-92
50011 93-88
50102 93-88/97-92
50035 95-85/102-92
50130 95-86
50030 95-90
50092 95-90/100-95
50104 97-92
50103 97-92/101-96
50214 97-92/102-97
50190 100-95
50198 100-95/110-105
50000 103-98
50191 120-115
oh, I should point out that the alloy radiator is meant to cope with 1.8 l engine.
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DIY Si
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| posted on 12/1/10 at 11:56 AM |
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50103 looks about right to me if you need a double contact. Or 50092 if you want to be absolutely safe, although with a big ally rad, I don't
think you'll have any issues.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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rusty nuts
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| posted on 12/1/10 at 12:19 PM |
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Why bother with 2 fans? My modified 1600 cc Xflow engined car copes very well with a single fan although lagging the exhaust manifold made a huge
difference in underbonnet temperatures as did a couple of vents in the nose cone and bonnet. A lot of production cars use a single fan with 2 speeds,
might be worth looking at?
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dhutch
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| posted on 12/1/10 at 12:53 PM |
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I tried to get advice on this but in the end just bought what made sense.
My engine stat opens at 85 so there no point of it runnignthe fan before that. Certainly it HAS to ut off at a temp above that or it will run
always.
I then figured my cooling look was fairly small, with a smallish (thin polo) rad for the engine (1900cc cvh) so it might as wel not cut in too late
either (boiling put of coolent is maybe 110deg)
Then picked something in the middle...
Not sure how well that plan will work yet, as currently the rad and switch is unfitted.
Daniel
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02GF74
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| posted on 12/1/10 at 01:34 PM |
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quote:
Originally posted by rusty nuts
Why bother with 2 fans?
I cooked my engine.
It cost me £ 100 for AA to bring mehome, is gonna cost £ 100+ for rebuilding the head (guides came loose) plus a lot of time spent fixing all of
this.
I have alloy radiator that is HOOOOGE so the engine is never gonna overheat (famous last words).
The radiator is quite wide so I can cover more area with twin fans than with one big one, maybe.... that is the thinking currently.
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James
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| posted on 12/1/10 at 03:35 PM |
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Don't you think all of this is a little overkill for what is, at a end of the day, a pretty bog standard engine.
No one else has had to go to this sort of levels to keep their engine cool, (Hicost's 450BHP Cossie is an exception!  ) isn't it more
likely you had an unusual fault of some sort that caused the problem in the first place? A Polo or Golf rad and a half decent fan is more than enough
for most people.
I'm concerned you're now going to suffer from over-cooling issues- having an engine running below temp is can't be good for it
either.
Anyway, not wanting to wee on your chips- just don't want you to go to unnecessary effort and expense. 
All the best,
James
------------------------------------------------------------------------------------------------------------
"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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02GF74
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| posted on 12/1/10 at 03:39 PM |
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quote:
Originally posted by James
I'm concerned you're now going to suffer from over-cooling issues- having an engine running below temp is can't be good for it
either.
just don't want you to go to unnecessary effort and expense.
... but if I keep the termostat, how can it be over cooled?
as for expense, if you knew how much I've been spending or red silicone hoses to try to fit the radiator to the engine, your eye would bleed! 
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James
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| posted on 12/1/10 at 04:21 PM |
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quote:
Originally posted by 02GF74
quote:
Originally posted by James
I'm concerned you're now going to suffer from over-cooling issues- having an engine running below temp is can't be good for it
either.
just don't want you to go to unnecessary effort and expense.
... but if I keep the termostat, how can it be over cooled?
as for expense, if you knew how much I've been spending or red silicone hoses to try to fit the radiator to the engine, your eye would bleed!
Agreed, but by that logic, as long as you've got a big enough radiator it won't overheat either. Seeing as pretty much everyone gets away
with a Polo rad' with engines ranging from 1.3 Xflow to 2.0 Pinto to Rover v8 that would seem to be all you need along with a single fan.
As long as the hot air can get out of the engine bay these car's should cool pretty well. I proved this on mine which was getting pretty hot by
temporarily removing the scuttle tray so air could get out through the cockpit... temps dropped dramatically!
Cheers,
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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britishtrident
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| posted on 12/1/10 at 07:22 PM |
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Keep it simple less to go wrong
(1) Polo rad has a lot more heat exchange area than the original Ford.
(2) One fan wired through a relay is enough
(3) Fit a single contact switch N.O. about 95c switch on For single contact switch see Intermotor 50041 (Volvo & BMW apps)
(3) If you have to drill and tap stick to M12x1.5 thread -- taps are relative cheap and easy to find and tapping is much easier.
(If you need a M12x1.5 Tap PM me)
(4) If you really want a duel contact switch to control two fans or two speeds on the same one fan see intermotor 50042 (BMW app) but needs suitable
socket -- it might be better to use 2 swtiches say 5040 and 5041. For cheap 50040 (on at 103c) see ebay item 310003594820 I bought one off the
same supplier a couple of months back.
Also see thread.
http://www.locostbuilders.co.uk/viewthread.php?tid=121137
If you want to do this PM me as I have spare 100c NO thermal switches.
The usual warning about making sure you have a by-pass connection on the coolong system applie.
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britishtrident
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| posted on 12/1/10 at 07:34 PM |
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Also if you want to get two speeds from a single fan wire a high wattage wire wound ressistor in series with earth side of the fan. Ffor the higher
speed just arange for the resistor to be shorted to earth..
50Watt 1 ohm Alloy case resistor should be OK for any fan that will fit into a locost nose it should slow the fan to about half speed Suitable
resistors can sometimes be found on ebay for a pound or so search on both "Wirewond" and "Wire wound"
[Edited on 12/1/10 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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02GF74
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| posted on 12/1/10 at 10:23 PM |
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BT - thx for info - given me some other ideas, especially re using different swtich with smaller thread i.e. much cheaper tap.
need to look tnrough the intermotor data.
if I were to do 2 speed thing, I'd try using 2 relays to connect the fans in series and then in parallel - don't like wasting power in
resistors.
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