Electric Fan Setup

[FBRacing]

Converting from clutch setup to electric on my 95 R33 RB25. On most cars, the ecu has a port where you can tap into it to gain a ecu governed switch even though the car comes with a clutch fan. Not real keen on those "kits" that stick a probe in the radiator core fins. I've looked at diagrams and schematics but unfortunately have been unable to locate a port. I also understand that nissan also did a electric fan on these RB25's from factory or is that incorrect? Any help would be appreciated.

[StevenCJR31]

I believe the only electric fan that nissan wouldve fitted would be for air conditioning

[jjman]

if you can do that it would certainly be better if indeed you can avoid using a probe into the coolant hose which is quite crude (best u can manage is to have it turn on at 92 n off at 86).

If you could also do it on a tunable ecu to have the fans cut in if automatically if road speed falls below 55ish...

I love my thermofan setup but know there is more in it. Also a really high performing thermofan that doesn't cost stupid money would be sweet (currently just 2x12inch Davies Craigs...)

[XRATED]

Why are you changing???

[XRATED]

And no, there is no 'port' for a thermo fan.

Just buy a kit with a scew in temp sensor and use a temp sensor adapter that goes inline with the top rad hose... or drill and tap the block/coolant passage on the intake manifold.

But why???

[niZmO_Man]

He wants to transfer the load from the water pump pulley to the alternator .

[89CAL]

Yeah it would only be possible with an aftermarket ECU

What is the reason for wanting to change the fan to electric?

It's alot of effort for no real gain in most cases

[Shoota_77]

I'd love to see a real calcualtion in the difference in drag but I can't see an alternators increased draw from the higher demend exceeding the driven fan load.

The greatest benefit as I see it is having greater control over your cooling. The problem with the viscous fan is that when idling at low revs is when the fan is least effective (when it's locked up) due to spinning at low speed. If you've just done a high speed run on the track and then slowed right down the viscous fan is going to do less than what a set of electric fans can do. If they're drawing more current at idle then who cares?

[Ben C34]

What car has an ecu out put for an electric fan that doesn't exist? I assume you have a different radiator also, get a fitting welded into it and screw in a sensor.

[Dan_J]

you can get thermo fan controllers off ebay etc that come with a relay and display and adjustable on fan temp settings.

i also think with a tune u can get the aircon thermo fan plug to run thermos as the trigger wire to the relay

[Ben C34]

you can get thermo fan controllers off ebay etc that come with a relay and display and adjustable on fan temp settings.

i also think with a tune u can get the aircon thermo fan plug to run thermos as the trigger wire to the relay

The aircon bit sounds good. I will check my nistune tomorrow to see if it can be done.

[zebra]

Viscious fan nearly always pulls more air at idle than the best twin thermo setup running flat out

[blind_elk]

If you've just done a high speed run on the track and then slowed right down the viscous fan is going to do less than what a set of electric fans can do. If they're drawing more current at idle then who cares?

Simple solution to that "problem" - when you get back to your pit bay, open the bonnet, let the engine idle until the engine cools. But if you've slowed down on the "cooldown" lap, the movement of the car through the air will cool the engine via the radiato (seemed to work fine for GroupA Sierras after a punishing practice session at Sandown). Which is why thermos can be set to turn on quite high (mid 90s, even) - they do not need to run just because the engine is running.

The problem I had when I tried to run a thermo was that I could not get much air, certainly less than the standard viscous fan draws, through the radiator to keep the engine cool on the track. Never had the engine overheat using the viscous fan.

[jjman]

All things being equal, the viscous fan is very good and mostly should be kept IMO (and I have swapped to thermofans).

The reason I did was because I needed a new radiator, like a project (so went for a 52mm with shrouded 2x12"fans), and knew what would be required and what the pitfalls may be.

Otherwise it is really only a mod that has any effectiveness, IMO, if you have the car in a cool climate, and don't track it. Otherwise the viscous is better/wins/ is probably needed.

Really, the only benefit to thermofans is that they take away that big constant load (viscous fan) to a more intermittent load that can also be turned on at will (if u add a switch- recommended) so that it can be turned on in traffic, or for a while before a 1/4 or short track sprint and then turned off when the time to mumbo comes and the motor/coolant is already cool for you.

I love this function. but otherwise it has been a lot of fiddling for a small gain. But ill swear to you it is noticeable- the drag a clutch fan makes vs no load at all (because the motor is already cool and the thermos are off).

Finally, in cool air n above 80km/h the thermos usually stay off and the temps stay low. Tho I have the 52mm (ebay cheapie tho) and plenty of ducting/ air chanelling to the radiator (which isn't on a stock skyline as its a clutch fan n so didn't need it)

Enjoy

BTW, anybody ever seen any of the engine build work by Nelson Racing? 1000-2000hp twin turbo v8's. Always running thermofans....

4:30 onwards

Edited August 29, 2013 by jjman

[FBRacing]

I'm changing for multiply reasons. It frees up crack horsepower. I want to be able to manage when the fan comes on and at what speeds. I want to clean up the engine bay. Using a custom radiator that a friend has built for me is actually much thicker and pushes closer towards the motor which also makes it where I can't use a clutch fan.

[FBRacing]

Also the amp pull that comes off a electric fan draws little current if properly installed with the correct gauge of wire at correct lengths will not alter ohms or step potential. Use of relays and capacitors play a roll. I use electric fans along with electric water pumps on all my race motors. I live in Arizona, USA where temps reach well over 115 degrees daily. I build off road race trucks and race thru the southwest deserts with electric fan setups. For those who honestly think it'll draw from the alternator so bad that it'll hurt more than gain, please research before stating that opinion. Until you physically feel the increase in throttle response from freeing up crank stress, don't bark. Mechanical fans are awesome for trucks designed for towing not for cars that are designed for 330km. All I was inquiring about is if these ecu's had a prong to accept a fan. Most manufacturers do put a ecu control prong with mechanical fan setups do to a wide variance of engine and drivetrain options. For instance, the 2001-2007 Chevrolet Silverado 1500 is the same truck throughout the whole pickup line up. They come with a mechanical fan from factory but if you opted for it and paid for it, a electric fan could be fitted. The manufacture than would derate your towing capacities do to limitations a electric fan can do under extreme towing conditions. I will be looking into a stand alone EFI system.

[89CAL]

I never said that an electric fan would drain more power then the viscous hub fan. I merely said that its usually alot of effort on an RB25 for very minimal gain, and from what I've heard alot of the kits dont cool as well as the viscous fan

Electric fans are fine in a race car because theres usually so much air going through the radiator from driving fast that the fan/s are off. But on a street driven car there is alot of time where airflow is needed and the viscous fan usually does alot better job of this.

In a street car, I don't see the point. I've never thought to convert mine because it works so well.

[FBRacing]

I never said that an electric fan would drain more power then the viscous hub fan. I merely said that its usually alot of effort on an RB25 for very minimal gain, and from what I've heard alot of the kits dont cool as well as the viscous fan

Electric fans are fine in a race car because theres usually so much air going through the radiator from driving fast that the fan/s are off. But on a street driven car there is alot of time where airflow is needed and the viscous fan usually does alot better job of this.

In a street car, I don't see the point. I've never thought to convert mine because it works so well.

Actually after crunching some math equations, a electric fan setup will increase throttle response, mpg, hp, and cooling efficiency by two factors. First cooling factor is that you're able to set when you would like to start cooling. This is key cause cooler your motor is, more horsepower achieved. Second is a significant gain in water flow. Since the RB has a belt driven water pump, that large plastic fan slows down ability of that pump to work freely. Especially once that clutch engages at higher temps. Once the fan clicks, the pump has a harder time pushing coolant through which creates a restrictive flow then creates coolant not cooling as quickly as it could. Figured this out by trial and error. Also by removing that plastic fan keeps those pain in the ass gaskets sealed up in the pump. So after having a long conversation with a close friend and owner of a custom race radiator shop, busting out the white board and dry erase markers, and pulling math equations from google we've come to the conclusion that it made no sense why Nissan ever installed a clutch fan on these motors. You can also easily rebuild your alternator to submit a larger amp payload at idle and picking up a compact deep cell gel battery like what Odyssey deliverers. Not only will this cure any doubts anyone has that it'll make your motor work harder to charge your battery but also create a dependable electrical system. But as I said earlier, I will be utilizing a stand alone EFI system that I can fully customize and retro fit for this motor. I've already made my HP goal, now I just am looking for reliability. SDS has worked for me well in the past and most likely use it again. Just trying to utilize the standard ECU. I'm the type of builder that is into better than factory installs. Cleanliness is the key. Thank you for your input.

[89CAL]

How the hell can the fan clutch kicking in have any affect on the water pump? If the water pump slows, the engine slows. It is absoloutly no different wether you run a fan on the pulley or not, the only difference is you wont get the slight drop in revs when the fan kicks in which is pretty marginal to say the least. The water pump is always spinning at engine speed (unless you have a slipping belt etc) so there is no real gain in water pump efficency by removing the viscous fan. The pump is driven by the engine, you cant say it has a harder time because theres a fan attatched to it. It will spin AT engine speed, all the time, with an electric fan, a viscous fan, or 20 fans

My ONLY argument has been that on a street car, the cost to do all these things does not give enough of a performance gain to justify it. How much for an electric fan setup deep cycle battery, new altenator and any extra wiring to suit? Compare this to $0 to leave it how a whole bunch of engineers designed it all those years ago. On a race-car fair enough. I was unsure what your car was for thats why I made sure to say 'on a street car' in my second post when I was elaborating on the first.

It doesnt make 'no sense at all' that Nissan used a viscous fan hub. When they work how they were designed they do the job very well. I have had my R33 GTS-t for about 5 years now. Never ever had a cooling problem, replaced the water pump at the 100,000km service but it was still in good condition, no leaks, no issues. Have run viscous fan from day 1, and I would say the only worthwhile cooling mod I have done is putting a cooling panel in.

If its a race car, put electric fans in. No problem. But I was talking, and always have been talking about cars driven primarily on the street

[mad082]

Yeah have to agree with the fan having little to no effect on the water pump. If your engine maybe only have about the same power output as a hamster on a wheel then the fan clicking in would drastically slow the engine down and thus reduce the cooling. But since the engine has plenty of power to spin the fan, there is no real effect on cooling.

and given that the viscous clutch fan rarely kicks in fully when the cooling system is working properly, it makes perfect sense why Nissan used a tried and tested, simple, reliable and relatively cheap fan system on their street cars