Author Topic: improving thermo fan  (Read 25327 times)

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Alfamania

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improving thermo fan
« on: October 21, 2013, 10:51:23 AM »
Hello,

Im not entirely happy with the original thermo fan on my Alfa 75 v6. I was looking at upgrading with an aftermarket SPAL brand 16 inch one. Im hearing good things about them...just wondering if anybody has ugraded their thermo fan on their Alfa 75 v6? Any advice would be really appreciated guys as its the only thing holding my 75 back from being pefect!!! :) Thanks very much
Alfa GT 3.2
Maserati Gransport
Alfa 75 V6 3.0
BMW 318i e36
Saab 9000cs
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Ford XE ESP 5.8
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jazig.k

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Re: improving thermo fan
« Reply #1 on: October 21, 2013, 11:19:23 AM »
I believe the best improvement will be had from making a shroud around the fan rather then just replacing it. So that way the air if funnelled to the fan... If that doesn't make sense, look at the picture. Air is then sucked through the whole radiator rather than where the fan sits... Upgrading the fan alone might help, but I reckon a shroud will out do a fan by itself.


scott.venables

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Re: improving thermo fan
« Reply #2 on: October 21, 2013, 01:20:20 PM »
What is it about the fan that makes you think it's not performing?

Alfamania

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Re: improving thermo fan
« Reply #3 on: October 22, 2013, 11:01:39 AM »
It is just not good enough...not sure how the other 75's are, but when stuck in traffic the fan just cant keep up with the heat, anyway I'd like to know other peoples experiences with v6 75's temperatures
Alfa GT 3.2
Maserati Gransport
Alfa 75 V6 3.0
BMW 318i e36
Saab 9000cs
Mazda Rx7 13B Extend port -Turbo
Ford XE ESP 5.8
Mazda RX-4 Coupe 13B Extend Port

jazig.k

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Re: improving thermo fan
« Reply #4 on: October 22, 2013, 11:16:55 AM »
On a really hot day, 40 plus, then my fan comes on and off every minute or so if I'm in town traffic. Any other day it operates just as much as any other car? But I wouldn't say it doesn't keep up, it works. Still, if you can improve it, then why not?

david sammartino

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Re: improving thermo fan
« Reply #5 on: October 22, 2013, 11:31:54 AM »
Alfamania, yes ofcourse you can always improve on the current setup and indeed a few of us have done these improvements, but simply on a standard 75, although the stock rad esp on a v6 does struggle to maintain temps, at the end of the day aslong as you arnt overheating, which if the fan wasnt adequate you wouldve done by now, i wouldnt be too concerned about the fan cycling on and off. In simple terms even if you were to improve the fan, a better fan would still be cycling on and off to maintain any temps higher then the thermostat temp, which brings me back to my radiater issue and the fact that it isnt good enough in my opinion to maintain thermostat temp.
I could go on, i also believe the waterpumps on idle dont push enough volume but were opening a can of worms here. My point being, dont bother lol

Alfamania

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Re: improving thermo fan
« Reply #6 on: October 22, 2013, 12:33:06 PM »
It is what it is i guess, maybe I just leave it then and do some more driving  :)
Alfa GT 3.2
Maserati Gransport
Alfa 75 V6 3.0
BMW 318i e36
Saab 9000cs
Mazda Rx7 13B Extend port -Turbo
Ford XE ESP 5.8
Mazda RX-4 Coupe 13B Extend Port

david sammartino

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Re: improving thermo fan
« Reply #7 on: October 22, 2013, 01:32:26 PM »
Exactly :)))

shane1750

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Re: improving thermo fan
« Reply #8 on: October 22, 2013, 06:50:03 PM »
This scan is from the Alfa Romeo V6 High-Performance Manual

Duk

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Re: improving thermo fan
« Reply #9 on: October 22, 2013, 07:29:37 PM »
Check out the 164 radiator. They tend to be a bit thicker and use wider spaced cooling fins. This way more air can flow thru the radiator and the actual air passages are less likely to get blocked with crap.
They can also be bought new off of eBay for quite a reasonable price.

If that doesn't fix your woes, then it is either an expensive drop in replacement aluminium radiator or you go about making something from another car fit.
I'm going down the 'something from another car' path, but it's been a bit of a pain in the ass and only the sort of thing I'd suggest if you like making and modifying things................  :o

VL-VS V8 Commodore Aluminium radiator:

jazig.k

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Re: improving thermo fan
« Reply #10 on: October 22, 2013, 07:38:19 PM »
Another option, which is drop in and needs no modification, is a 3Lt radiator. They are about 10mm thicker than 2.5Lt and twinspark radiators. Running a 2.5lt rad in a 3lt makes a difference for how fast the car heats up and switches on the fan [I ran one while had my 3lt rad' cleaned].

colcol

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Re: improving thermo fan
« Reply #11 on: October 22, 2013, 10:02:48 PM »
You could even think about a Davies Craig electric water pump that pushes water through at a constant speed, they fit into the radiator hose, but sometimes flow is not the answer, as if the coolant flows too quick, then it can't absorb the engine heat and  deposit all the heat to the radiator, also try a higher pressure radiator cap to increase boiling point and shrouding of the radiator can increase airflow by 10%, instead of it leaking airflow around the sides, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

Alfamania

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Re: improving thermo fan
« Reply #12 on: October 23, 2013, 08:07:39 AM »
I have a 3 litre guys. Is the 164 radiator straight fit? Jazie.k I dont understand what youre trying to say? do you mean drop in a 2.5 radiator in a 3 litre engine? Isnt it the same radiator for 2.5 and 3.0? I was just looking at puting in a high performance Spal 16 inch fan? the Spal fan amp rating is 17 to 21 amps. Would my 3 litre 75 handle that? or do i need an auto electrician to modify relays? Thank you  :)
Alfa GT 3.2
Maserati Gransport
Alfa 75 V6 3.0
BMW 318i e36
Saab 9000cs
Mazda Rx7 13B Extend port -Turbo
Ford XE ESP 5.8
Mazda RX-4 Coupe 13B Extend Port

AikenDrum105

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Re: improving thermo fan
« Reply #13 on: October 23, 2013, 09:24:06 AM »
Hi

I've had great results with a SPAL fan recently  - the fans with the curved blades, and the support ring connecting the outer tips of the blades tend to have the highest CFM.   Tend to be quieter too.

I'm sure you've checked it already,  but sticky thermostats are often the cause of cooling system woes...  (I've had two dodgy twinspark thermostats cause issues with my car - one didn't close fully so the car took ages to heat up,  and the next one didn't open fully - causing the car to eventually run out of cooling overhead in summer traffic gridlock...)   

It's worth checking the condition of the wiring in the car - possibly that will restrict the current more than anything, the fan will run slower if the wiring (which has a little age on it now too)  can't pass that much current (or was designed with a lower current in mind for the stock fan)

You might even find the stock fan runs much faster when you connect it directly to the battery,  as opposed to running via the normal wiring loom  - meaning you could get additional stock fan performance with some wiring modifications. his made a big difference to the cooling in my old GTV6.   ( Another way to check is to check (with the fan running) the voltage across the fan connector and the voltage at the battery - see how much drop there is. )

I guess if you're going to need wiring mods to run the SPAL fan anyway - you could try running the stock fan that way first to perhaps save the cost of a new fan.

I don't know if any of that helps...  but good luck !



 

Scott
'66 Giulia Super 105.28.720988 TS+MS3+ITB+COP
'65 Giulia Sprint GT 105.04.753710
'04 156 JTS Sportwagon

Earlier follies...
'66 Duetto 105.05.710057
'85 GTV6
'71 1750 GTV

Beatle

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Re: improving thermo fan
« Reply #14 on: October 23, 2013, 09:51:19 AM »
Are you sure the rest of the cooling system is perfect?  No amount of extra airflow across the heat exchanger will help if the waterpump is slow at idle, or if there are other reasons the heat transfer is inefficient (clogged radiator, scale in the passages, wrong coolant mix, T-stat).  Most systems are designed with very little in the way of excess efficiency, so it only takes a small change in the overall efficiency and your temps quickly spiral uncontrollably to boil point.

Having had a bit to do with engine conversions in 4WDs, and mucking about with changing fans, rads etc, I can tell you the shroud is a critical component of getting max flow from your fan.   Tip losses and air recirculation are huge with an unshrouded fan.  The shroud also helps pull air across the full surface area of the radiator.
Paul B
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Past:
'79 GTV - Loyal 1st love
'76 GT - Track entry
'89 75TS - Saved
'76 Alfetta - Sacrificed
'83 GTV6 - NT bullet
'67 Duetto - Fun
'66 Super - Endearing
'92 164 - Stunning
'85 90 - Odd
'04 GT 3.2 Rosso/Tan - Glorious
'02 156 V6 Auto Rosso/Tan - Useful daily