[kismetcapitan]

viscous or electric? for comparison purposes, let's say the electric is capable of pulling well over 4,000cfm, is programmable, and draws, say 25 amps current when running.

what is better and why?

 

[arnout]

viscous is the best no doubt. There is no free energy so when you free up energy with not driving the clutch you will stress the alternator more. Also I have seen (even today!) blown fuses and thus overheated engines. This never happens with viscous.

 

[moosedoog]

viscous is the best no doubt. There is no free energy so when you free up energy with not driving the clutch you will stress the alternator more. Also I have seen (even today!) blown fuses and thus overheated engines. This never happens with viscous.

but viscous couplings can fail and do nothing as well.....depends how well you keep an eye on your guages when driving. im paranoid and spend more time looking at guages than the road.im confident ill not overheat anything i drive!!!! (touch wood)


id go electric every time. i hate the idea of running the viscous all the time when its just not needed, robs power and fuel. in my experience a good electric fan always seems to pull more air through the rad at idle which is when you want it most.

 

[souroull]

the viscous fan will spin even if the fan clutch is blown (never seen a seized one). ive been driving with a bad fan clutch on my m3 for 6 months before summertime hit and my temps started to creep up in heavy heavy traffic.

theres no point in adding more complexity (not to mention high cost) only to create more fail points and divert the drag of the fan to the alternator.

as for idle temps, if its hot enough outside to warrant the use of the a/c, then that one is spinning along with the viscous at idle and helps aswell. maybe get a beefier a/c fan ?

 

[kismetcapitan]

I had to order a new viscous fan clutch, I can move my fan quite easily with my fingers...got me thinking about going electric. But to pull the same kind of air - twin 13.5" fans, up to 30 amps current draw.

 

[Marko R1]

my tuner told me that i'd run into heating problems on the street with electric fans & that you cannot replicate the efficiency of a clutch fan

 

[T04Z GTR]

Viscous fan all the way...

Although a do run a 13.5" electric fan myself, & do get some over heating problems when stuck in traffic for even a short period of time... Will have to add another to try & solve this problem...SOON....

Put it this way.... 700+ Hp running a Viscous fan to cool your engine.... Enough said really..!!

 

[NISFAN]

The ultimate solution has got to be an electric fan and electric water pump

As for using a GTR in heavy traffic.............WTF were you thinking????:chuckle:

I use two fans and can idle the engine as long as I want.
It takes some doing to make BOTH of my fans come on too (seperate triggers for each).

Note: The fans I use are not even very high powered units, but are fitted to larger core rad, and for use in the UK (cooler dryer air than Seoul).

Other points on my set up are:
I have the Nismo stat fitted, and use N1 water pump. I also only have an IC and the rad in front, no AC rad and no oil cooler in front of rad (side mounted). ATI damper (not sure whether this has same water pump drive speed???) , and stock water pump pulley.

Stacking 4 radiators in line with each other is poor practice.

I suspect the water pump won't be pumping much flow at idle, especially if an N1 pump is fitted.

 

[kismetcapitan]

I do have, and can't give up, the A/C radiator. Removing it would help cooling, but really, the only times the car gets excessively hot is, yep, in traffic jams in Seoul afternoons. I took the car out last Sunday because I decided at the last minute to bask in A/C rather than sweat it out on the bike and all the radiated heat from the road, the sun, and millions of cars not moving. Should have chosen option B...but in doing so, my car becomes a vampire. There was an 8 month stretch where the car literally never saw the sun - it ran at night, and was parked before sunrise...

I might consider running both options (not at once). Installing electrics during the winter - I have problems *warming* the car during the brutal Seoul winters and could do without a fan making things worse (I have a Trust twincore radiator, N1 pump, and Nismo thermostat fitted). Removing the viscous fan takes five minutes, and an electric fan setup, if the brackets are designed for quick removal, can also be done rather simply.

 

[souroull]

so, wait a sec, why do you want to run electric fans so much?

i think i missed the benefit of spending 5-600+ bucks and swaping out systems every year, care to enlighten me

thanks

 

[kismetcapitan]

it started when I priced a new viscous clutch and found it cost as much as a high-end twin-fan system. Then I thought about what a pain it is to get my car warmed up in the winter.

Just idle thoughts really, and coming to fully understand how a dual puller fan system works, the controller, etc. If I had both, I could stick the viscous fan in April, and install the electrics in November.

 

[souroull]

you can get a used one for 40-60 pounds. its not like they're fragile. no need to dump 200 odd for a new one

 

[NISFAN]

It's a shame, people are missing out!!!!

Removing the viscous is high up on my best mod list. Makes a big difference to the rev response of the car at low revs, and you can feel the extra hp on normal road pull offs. Plus it gets rid of that gay fan drone, and allows you to really hear the engine.

Don't believe me? Try it, it only takes 2 minutes to remove the 4 10mm nuts holding the viscous onto the water pump pulley.

 

[fabianGTR34]

I personally prefer an electric fan, but not because it is superior in cooling performance. But it is more efficient, it is only used when needed. And if you make descent connections it will be very reliable too. Most cars are equipped with electric fans and it works fine.

The cooling fan is only needed when the engine is hot, and when the vehicle speed is low. (low driving airflow) So useful when you're stuck in traffic. That is the reason most 4x4 terrain vehicles like patrols have viscous fans, because then are often highly loaded on low vehicle speeds. But on a track or road car like a skyline I think this is less than 5% of the use.. so 95% of the time you are burning fuel for ****. I agree that the cooling performance of the viscous fan is a little higher, especialy because it is always on.. and also because the speed goes up with the revs ans temp.. Unfortunately this is often not needed. When a descent fan (or fans) are chosen they will cool more than enough.

The pro's of electric fans are:
- better efficiency of the engine, since it wont have to drive a fan when not needed. Fuel economy should be better. And a little hp gain could be seen.
- more space in the engine bay
- no "4x4 terrain vehicle sound (and clearer engine sound )
- better engine response

Con's of electric fans:
- less cooling power but still enough if done right.
- relies on electric components (does not have to be less reliable)

The pro's of viscous fans are:
- reliable
- speed depends on rpm and temp.
- keeps the radiator cooler?

Con's of viscous fans:
- always drain power (fuel) also when not needed.
- Noisy (4x4 terrain vehicle sound)
- uses a lot of engine space and does not look sporty (to me)

 

[kismetcapitan]

well I just got my used viscous clutch in the mail so I'm replacing mine with viscous again.

However, I am still seriously considering it. On the one hand, Nissan must have had good reason to go with a viscous. On the other, at least theoretically, electric is better. There are electrics that can pull at least as much air as the stock fan, and only run when needed. Cold winter starts. And actually, anytime I'm on boost - with lots of horsepower, the car tends to go fast. If the air is anything but absolutely scorching, a hard blast on the highway will drop my water and oil temps five degrees, even though the engine is working at full power.

So in a sense, an electric fan is working and drawing power when you least need it (slow driving). And freezing cold starts - 4000cfm of arctic air blasted at the engine block makes for slow warmups - if my car's been parked outside, 20 minutes to get water and oil temps anywhere near safe to start boosting.

 

[ru']

Just to add to the pros and cons I'd say the viscous would be more efficient when it's hot, due to less power conversion (electric fan needs movement > electricity > movement).

It would be inetresting to know what sort of load the viscous does actually place on the engine at different temps, but it wouldn't be easy to work out/measure I guess. Lets face it, when it's not hot you can spin the fan by hand easily so there's not much power loss in that situation anyway.

 

[NISFAN]

ru'

I know you can spin the fan easily when cold, but trust me, at engine speed it uses ALOT of power.

How do I know this? You can feel the extra power in the engine, and the rate of acceleration of the engine without the fan, and it is very different. I would put money on it that the fan uses more power than the aircon running, all the time.

I urge you to do the test, take the fan off, and blip the throttle a few times. You'll see how much power it takes, by how much faster the revs climb without it.

The problem with the viscous fan, is it is not very efficient when it comes to moving the right air. There is lot's of spillage between shroud and backside of rad, fan and shroud, etc etc.

Puller electric fans are pretty good at moving a large % of the airflow through the rad which is what is needed. And the fans only come on on the odd occasion. The viscous is a very wasteful device, and weighs a ton too.

 

[ru']

Fair enough, I've not tried that.

 

[chaz_r33_gtr]

hmm i might give that a shot for a laugh... if i do a short jorney to work and back (8 miles each way) I assume it will be safe.. just keep an eye water temps and stop if they are getting too hot?

I guess at speed a fair chunk of air wil be going throgh the radiator anyway.. its more of a problem if im sat in traffic for ages (which wont hppn on my ony)

Il report the findings

 

[mifn21]

How long would it take to disconnect and remove the fan? If its not a lot of work it'd make sense to remove it totally for trackdays...

Hmmm