Author Topic: improving thermo fan  (Read 25328 times)

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Alfamania

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Re: improving thermo fan
« Reply #15 on: October 23, 2013, 02:07:28 PM »
My 75 doesnt have a plastic type shroud cowling like how all newer cars have....does it mean mine is missing? It just has a steel round ring frame and 4 mount tips for the fan? Is the 164 the same? Was thinking maybe using something from the 164 for upgrade but I reckon same?
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Duk

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Re: improving thermo fan
« Reply #16 on: October 23, 2013, 04:20:14 PM »
I have a 3 litre guys. Is the 164 radiator straight fit?

I was told about the 164 radiator into TA Alfa's by For90s. Maybe send him a PM to confirm.

david sammartino

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Re: improving thermo fan
« Reply #17 on: October 23, 2013, 04:20:31 PM »
From memory 164 rad hose outlets/inlets are the opposite to 75, cant rember as it was awhile ago but i think it was abit thicker which meant with a fan om the back it fouled the cross member. All these issues can be addressd easily if your handy with the tools, but brings me back to my point of not worth it on a standard car.
I have a 147 gta also and youd just love the hoovecraft thermo cycling on and off on a hot summers day then lolll alot of newer cars seem to address these issues with variable speed fans and such, but i just dont think a standard car is at that level of need.
To put things into perspective for you, my 75 is mildly modified and runs a xr6 turbo radiator, fan with shroud, ducting and falcon 75 degree thermostat, and temp can still creep up slowly idling in traffic with the fan cycling on and off. And i can control my fan via the ecu, so can do what i like with it!
Brings me back to my point about water pump flow, maybe even possibly coolant passages compared to modern cars, as a friend of mine had the same setup in his factory xr6 turbo and idling on a hot day the fan didnt have to cycle on half as much.

In regards to higher pressure caps, im currently inti a volvo 850 resovoir with a 21psi cap, but my setup is obviously not stock, when i was trying to improve my standard setup i tried, 164 1bar cap and gta 17 psi cap, both of which cracked my original, and later replacement original resovoirs.
The only thing i can say made a difference was the lower temp fan sensor, which i think held the fan running longer before cycling off. I actually stil got this and you can probly have it for next to nothing like 20$ as i dont need this anymore.
Apart from that, make sure the obvious basics are all in check and enjoy driving your 75 :)

Duk

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Re: improving thermo fan
« Reply #18 on: October 23, 2013, 05:39:50 PM »
By running a higher pressure cap, you don't really guarantee anything.
Unless you measure it, how d you know the pump can actually pump to the higher pressures?
And while the boiling temperature goes up with higher pressure, I doubt coolant can actually absorb and dissipate more heat energy as a result.

However, you may get advantages by running a higher system pressure AND running the pump faster, because the higher operating pressure should delay the effects of cavitation in the coolant as the pump starts to run too fast.
Basically, if you run the pump faster, the point at which cavitation of the coolant occurs will happen at a lower engine speed. But because the coolant is under more pressure (because of the higher pressure cap), the point at which the coolant starts to cavitate should be pushed a bit further up the rev range.

A properly shrouded radiator fan would still be a good thing as it will increase air flow thru the radiator when the fan is doing most/all of the work. But the fan and shroud will be a bit of a flow restriction at speed.
I have seen fan shrouds with little hinged flaps around them, so that when the fan is trying to suck air thru the radiator (and so cause a pressure slightly below atmospheric pressure), these flaps are sucked closed. But when the car is moving and the air flow thru the radiator is higher, these flaps get pushed open by the air flow and allow more air to flow thru the radiator.
« Last Edit: October 25, 2013, 05:16:38 PM by Duk »

david sammartino

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Re: improving thermo fan
« Reply #19 on: October 23, 2013, 09:20:41 PM »
Hi duk, yes i agree with all youve said, esp about the caps and measurements, basically these are like a bandaid solution which would require measurements, but i guess sometimes we just need to bite the bullet and suck it, as time may well be spent doin something else then doing a thorough engineering test. At the end of the day takes 2 secs to unscrew and swap a cap and read the gauge back to back driving. You are correct though scientifically.

In regards to the fan shrouds i have seen those flaps i think on a corolla or some other toyota and on some audis, fact is though unless you are quite familiar with the frontal aero of our cars, or for any matter any specific car, whos to say it wouldnt be detrimental, as in theory and practice some times things just dont work, as in the extreme you could create any effect but like you say without testing who knows and infact why bother. Standard car, standard fan=drive and just dont pay any attention to the fan cycling lolll time would be more well spent  cleaning the car for concorso or something rather then opening a can of worms on an issue thats not there. I agree with all youve said duk, but alfamania just trying to save you some time/coin bud, if it aint boiling and overheating, you dont have an issue.

Alfamania

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Re: improving thermo fan
« Reply #20 on: October 24, 2013, 02:20:00 PM »
Cooling system is clean as I have recently recoed the top end of motor with new top end gasket sets and whole system flushed. Its just the fan....it comes on at 90deg and I can just see it be on for a long time until it turns of...and thats in cold weather let alone in hot summer day. Anyone know the amp rating for the factory set up? Im looking at getting a high performance 16 inch Spal fan apparently rating at 17 to 21 amps. I just need a stronger more efficient fan that doesnt need to stay on forever until it brings the temp down. I hope Im making sense. Thank you
Alfa GT 3.2
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four90s

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Re: improving thermo fan
« Reply #21 on: October 24, 2013, 03:29:07 PM »
The only thing i can say made a difference was the lower temp fan sensor, which i think held the fan running longer before cycling off. I actually stil got this and you can probly have it for next to nothing like 20$ as i dont need this anymore.

Hi David,

Do you know the temp range for that sensor and where did you get it? If nobody else wants it I'll take it for the $20.

Cheers
Steve Adelaide
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(33 Alfas and some other things since 1979)

david sammartino

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Re: improving thermo fan
« Reply #22 on: October 24, 2013, 04:35:44 PM »
To be honest ill have to check i think its got it stamped on it somewhere, ill let you know. I got it from mille miglia years ago from memory.

Alfamania, have you done a basic check with the multimeter to see if you have a major voltage drop possibly causing the fan to run slower? Also is it blowing correctly, as in pulling air backwards and not forwards? Also may wanna check your cooling hoses all connected properly, recent headwork rings alarm bells to me, was the car doing this before the work??

GTVeloce

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Re: improving thermo fan
« Reply #23 on: October 24, 2013, 07:05:21 PM »
Does the v6 create a lot more heat than the TS? My TS was able to handle 45C (Dubai) in traffic without a problem. If I had the AC on whilst standing still it became a problem but once on the move it was fine. Alternatively I just turned the AC off while stationary. All I did was make sure everything was in perfect original condition and new hoses.

Obviously if the v6 creates much more heat then I guess this doesn't help much!

Andrew Bose

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Re: improving thermo fan
« Reply #24 on: October 24, 2013, 07:38:37 PM »

Have you considered something like these?

Water Wetter
http://www.redlineoil.com/Products.aspx?pcid=10

or waterless coolant
http://www.evanscoolants.com.au/all-automotive-products.html

Maybe with the high temperatures and air con we use in Australia something along these lines will do the trick or if you want you can get a custom radiator made from someone like this mob.

http://www.autocooling.com.au/

I have heard good things about Water Wetter but have not heard of waterless coolant until recently so do a bit of homework. I use Autocooling for stuff other suppliers cannot fix at work so I am happy to recommend them but I work with buses and they have very large and expensive radiators as standard so check with them first as I spend $2500.00 (not my money and time off road is expensive) on a recore without batting an eyelid.

Good Luck.
Bosey

Alfa166

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Re: improving thermo fan
« Reply #25 on: October 24, 2013, 08:10:27 PM »
Get a replacement Thermo fan , the original design of blades of the Alfa one of that era is very poor for both airflow capacity and quietness.

Alfa and any italian car for that matter have never been good at design of thermo fans and interior blower fans. That is why in the older era Alfas the internal heater airflow is so poor and noisy. Not that much improved on the later cars either. As someone else suggested get the biggest aftermarket fan you can source for it. This will allow one less cycling of the thermo fan and in turn a lower draw on and already marginal electrical system and much quieter operation. Have you ever noticed how quiet the equivalent Japanese cars is in terms of thermo fan compared to a blaring thermo fan on an Italian car. 

david sammartino

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Re: improving thermo fan
« Reply #26 on: October 24, 2013, 09:38:25 PM »
Or you could just convert to a clutch fan, most japanese cars of that era seem to use those :)

Duk

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Re: improving thermo fan
« Reply #27 on: October 25, 2013, 05:24:45 PM »


or waterless coolant
http://www.evanscoolants.com.au/all-automotive-products.html


I have heard good things about Water Wetter but have not heard of waterless coolant until recently so do a bit of homework.

The funny thing is, pure race cars like V8 Supercars and Formula 1 cars just use straight, distilled water.
There aren't many, if any other liquids that can absorb and dissipate heat like pure water can. And anti-freeze/boil additions actually reduce the water's ability to do it.

colcol

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Re: improving thermo fan
« Reply #28 on: October 25, 2013, 05:45:49 PM »
In motor racing they need a coolant that will dry up quick when spilt on the track, some coolants and anti freezes are too slippery and don't dry up as quick as good old water, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

Duk

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Re: improving thermo fan
« Reply #29 on: October 25, 2013, 06:21:46 PM »
In motor racing they need a coolant that will dry up quick when spilt on the track, some coolants and anti freezes are too slippery and don't dry up as quick as good old water, Colin.

A good point, but pure water is still a better coolant than anything else you or I can get our hands on...............