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Spitfire Mark III Electric Cooling Fan


northernbrowns

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2 hours ago, cliff.b said:

So from what I have seen with my own car (Spitfire with wide rad), electric fans will stop a car overheating but it runs cooler with the mech fan fitted.

But running cooler is not a benefit. The engine works best at the hotter end of the range it's happy with.

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50 minutes ago, NonMember said:

But running cooler is not a benefit. The engine works best at the hotter end of the range it's happy with.

Quite possibly. I'm just sharing my observations that the car ran cooler with the mechanical fan.

Individual owners can decide for themselves if that is a good thing or not. 

I really don't know 🙂

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So managed a good first run with my new fan controller fitted  as it seems to be working so thought I'd give details, in case anyone was interested.

Car's a Spitfire Mk IV with a 'fast road' spec. engine and full width rad.  No mechanical fan, just an electric 'push' fan.

Fan control was via a Rovotec adjustable controller (in the rad. exit to water pump inlet hose) that basically had it comming on at 3/4 and switching back off at 1/2.

Fan control is now via a Stoney Racing 30mm/95°C controller from eBay (in the same place as I had the Rovotec one).  This seems to come on just over 3/4 and switch off when back down to 3/4. This seems stable and I've not had any running issues - though part of me wonders if a 90°C switch might not be better, as it's in the rad. exit rather than the recommended inlet hose (but probably only better for me looking at the gauge, not necessarily for the engine 🙂).

And out if interest I only discovered the Rovotec controller had died en route for a weekend away last Bank Holiday, which resulted in a pit stop at a Halfords to buy/hack in a mechanical switch. This meant a lot if driving with the fan left switched on, even when not needed and like that the needle just sat at half way. Logically this means (on my car and with the individual temp. sender fitted to it) the middle line must be 82°C (or whatever temperature the 82°C thermostat fitted in my car is actually opening at).

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I think if it behaves itself in slow traffic at 3/4 gauge youve cracked it.

Not sure I understand the logic of the last paragraph given that when driving at speed the fan, either electric or mechanical, shouldnt make much difference to cooling...

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In the last paragraph I was just giving a baseline of where the needle sat driving fast/slow/in traffic with the fan running full time, so an indication of when the thermostat opens/how low it CAN go and also context for how much hotter it's new position is. If it had been 1/4 with the fan on 24/7 moving to 3/4 would be quite an increase. Just moving 1/2 to 3/4 is much less of one. And there's no point me fitting cooler and cooler switches to get the needle to the 1/4 mark as, on my car, it's never going to happen.

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On 13/05/2022 at 16:08, cliff.b said:

Quite possibly. I'm just sharing my observations that the car ran cooler with the mechanical fan.

Individual owners can decide for themselves if that is a good thing or not. 

I really don't know 🙂

As I didn't know I thought I better read up on this a bit and there are plenty of opinions to choose from lol

However, sifting through all this information I found the following made sense to me.

1) Oil should ideally get to 100C so that any water gets boiled off.

2) A typical thermostat isn't fully open until about 10C above its nominal value (so 82 Deg thermostat fully open a bit over 90.

3) In typical road driving conditions, oil, once warmed up, is about 10C hotter than the coolant temp.

So if all this is true it would appear that everything is just about where it should be, almost as if by design lol

As long as we get hot enough that the thermostat fully opens and not so hot that the oil is compromised.

 

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2 hours ago, johny said:

As I say the maximum running temperature of my Vitesse doesnt seem to be set by oil breakdown or coolant boiling but the happiness of the engine. Too hot and I get pinking on acceleration and poor idle☹️

Is that track use or on the road?

I sort of assumed that in normal use, the idea was to avoid it getting that hot 🤔

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1 hour ago, johny said:

yes can even get run on if stopped from too hot (3/4+ on the gauge) and then hot starts are more difficult whereas now I keep the gauge around 1/2 shes happy😍

"She's Happy" is one of the secrets of life lol

 

  • Haha 1
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