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Should I Remove The Factory Clutch Fan On My Gtr?

Marko R1

By Marko R1,
in Engines & Forced Induction

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NSNPWR Rising Star

NSNPWR

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Not true It is a thermostatically controlled device that when operating normally will vary the fan speed independently of the engine speed. if the radiator is red hot it will still be fully engaged irrespective of rpm. It is the reason thermos are generally inefffective for Hard driving sessions as they are fixed speed and cannot pull enough air through the radiator at high rpm high load instances... our race car is a prime example we went back to a clutc fan as we found the $700 thermo setup we had could not match the std $100 clutch fan for cooling.... hence the clutch fan is back on and we can thrash it as hard as we like with no overheating.

key points about Thermal Fan Clutches;

  • Controls fans speed based on temperature
  • When at high speed, the Thermal Fan Clutch can provide high speed operation provides maximum cooling with it may be needed. When engine speed is low, the fan may be disengaged if not needed, providing fuel savings and noise reduction. Again, tied to temperature rather than shaft speed.
  • Thermal fan clutches have a greater life expectancy than a non-thermal clutch
  • Thermal fan clutches are briefly engaged at cold start-up
  • Thermal Fan Clutches engage at about 170° radiator air temperature, which translates to about 30° lower than the actual coolant temperature.

Im aware of all the info you posted above...but the fan doesnt spin to 8000rpm with the motor, it will not or should I say SHOULD NOT remain FULLY ENGAGED at engine speeds above 3000ish rpm as they are not designed to spin that fast...From my reading, there are instances where fans that are locked on (as mine was) have been spun too fast for too long and have shattered as a result...

...and what was this '$700' thermo setup??? Does that include a radiator? Even 2 Davies Craig 16s wouldnt cost you more than $500 retail.....and please show me where I can get an RB26 Clutch Fan for $100...Lol.

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Not true It is a thermostatically controlled device that when operating normally will vary the fan speed independently of the engine speed. if the radiator is red hot it will still be fully engaged ir

Bond Proficient

Bond

Posted
Posted

After 15 years a tiny un noticable weep is enough to drain the fluid inside.

If yours was stuck on it was not because of the fluid. The bi metalic spring would have most likely been your problem.

This does work as i have done it twice and many others have also done it on other vehicles. Skylines are just like any other car.....nothing magical.

Swiper the Fox Grand Master

Swiper the Fox

Posted
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My car has never overheated...can run it all day on the dyno without issue.

changed from engine fan to thermo and had overheating issues...changed back to engine fan...now all cool.

STATUS Grand Master

STATUS

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Im aware of all the info you posted above...but the fan doesnt spin to 8000rpm with the motor, it will not or should I say SHOULD NOT remain FULLY ENGAGED at engine speeds above 3000ish rpm as they are not designed to spin that fast...From my reading, there are instances where fans that are locked on (as mine was) have been spun too fast for too long and have shattered as a result...

...and what was this '$700' thermo setup??? Does that include a radiator? Even 2 Davies Craig 16s wouldnt cost you more than $500 retail.....and please show me where I can get an RB26 Clutch Fan for $100...Lol.

Your failing to remember the clutch is similar to a torque converter it is always slipping and does not run FULLY locked at high rpm, there is still some % of slip therefore should never reach 8000rpm regardless, it is more common for the R33 fans to explode as they crack around the moulded mount not cause they are over spun.

I think you may be confusing fan rpm and engine rpm (in your reading) as many clutch fans on older stuff were rated @ 3500-4000rpm (fan speed) the older stuff also ran approx 60% of water pump speed. On newer cars the fan's RPM is generally 25% of the engine's RPM below 62C, 80% of the engine's RPM above 85C, and otherwise somewhere in between

davies craig fans are average, we use spal at a minimum or in the case of race cars we use flexalite kits which have the highest CFM ratings (hardiman is the importer), if you need a few GTR clutch fans lets me know... ooh and most thermo fans (eletric) are rated in free air, when attached to a rad they drop substantianlly.

STATUS Grand Master

STATUS

Posted
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btw the viscous couplings are available aftermarket much cheaper than nissan. I got one thru UAS recently because mine was locked on

$80 for the davies craig ^^^^

**RB2530** Proficient

**RB2530**

Posted
Posted
Status - i thought conventional wisdom was that any sort of fan does SFA at speed, as the air pressure generated at the front of the car pushes much more air through the radiator than the fan, and therefore you might as well just turn the fan off at high speed. Sounds like that is not the case from your experience. Could the thermo shrouding have been restricting airflow?

+1 from me on this...

I always thought any cooling fan (clutch or electric fan) was there just to pull air through the radiator while the car was stationary or close to it. Road speed air would move heaps more air through the radiator than any fan behind it could.

The intent of the clutch in the fan is to slip and therefore limit the fan rpm when engine rpms are high. The clutch is a simple viscous coupling which slips more as its temperature increases. Thats why when they are cold they slip less and as the oil comes up to temp, it slips more. When you get stuck in traffic and engine rpm drops, oil temp in clutch drops and it slips less..ie more drive to fan when it is needed.

STATUS Grand Master

STATUS

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+1 from me on this...

I always thought any cooling fan (clutch or electric fan) was there just to pull air through the radiator while the car was stationary or close to it. Road speed air would move heaps more air through the radiator than any fan behind it could.

The intent of the clutch in the fan is to slip and therefore limit the fan rpm when engine rpms are high. The clutch is a simple viscous coupling which slips more as its temperature increases. Thats why when they are cold they slip less and as the oil comes up to temp, it slips more. When you get stuck in traffic and engine rpm drops, oil temp in clutch drops and it slips less..ie more drive to fan when it is needed.

the fan's RPM is generally 25% of the engine's RPM below 62C, 80% of the engine's RPM above 85C, the speed/slip is controlled by temperature the temperature control is via the BI-METALLIC strip on the front of the fan... it does not care if your doing 100000rpm or 100rpm it will regulate the fan speed by temperature only.

Angus Smart Grand Master

Angus Smart

Posted
Posted

Shit, so the thermo fans i have in the garage are useless? and that i am going to have problems when i get the car back together?

can any amount of shrouding ducting make this work? or do the fans simply not pull enough air thru the radiator?

i'd rather make some nice metal work than find the clutch fan again..

SiR_RB Grand Master

SiR_RB

Posted
Posted

when the engine is bone cold, and you give the fan a spin with ur finger, how loosly should it be ?

when i give mine a spin with my finger, it will turn about 90degrees from the top of the radiator, i thought they should atleast turn more then half way with a push !

mine has issues of coming on after 10 - 15mins of driving, robs u of power and sounds like a cyclone under ur bonnet when u rev it

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