Radiator Fan

CHICKENHAWK · Dec 3rd, 2003, 09:53 AM

Hey guys. I was just looking under the hood and I was wondering
If I could remove the fan on the belt pulley and be OK since there is a fan
on the engine side of the radiator. I did not realize the things came with a
clutch fan and a electric fan on the radiator. Are they BOTH neccessary?
Can I take the clutch fan off? On my old stang (91 LX 5 LITER), I took the fan off and put on an electric fan and I dropped 4 tenths off my qtr mile! 13.9 to 13.5. Thanks for the help and flaming in advance.

BlueBOB · Dec 3rd, 2003, 10:31 AM

i wouldn't take it off unless you were planning on puttin electric fans on... my buddy did it to his s14 and his revs were smoother... it's a good mod... don't think you'll drop .4 off your 1/4 mile time... but it'll help in general...

ps... i'll let drift and them flame ya...

CHICKENHAWK · Dec 3rd, 2003, 02:31 PM

Hey thanks man. I not a newbie anyway, I have been in another forum for several months now. Don't know alot, but sometimes I suprize myself. But I have to pay my dues in this forum, I know how it goes. But thanks for your help. I am also a KA24DET fan all the way. Seen it done, 425 rwhp - 12.3 qtr mile @123mph. Was not mine, did not know the person, not taking props, but he only had about 6 grand in the car. The car cost 2 grand, and about 3500 of it went under the hood (Forged internals and BIG turbo). 91 240 fastback, pearl white. Beautiful!!!!!

cls12vg30 · Dec 3rd, 2003, 02:31 PM

I did the same thing to my S12 this past summer. Like your 240, my 88 200SX SE V6 had the belt-driven fan and then it had an electric fan in front. I can tell you that the electric alone is probably insufficient to cool your engine in warm weather. My radiator is weak, and the electric fan's thermo switch stopped working last spring, so I wired up a dash switch to control the fan, if the temps started to climb I'd flip it on.
Then during the summer I decided to go all the way. I tore out both the belt fan and the electric fan and installed a side-by-side dual electric fan setup that I got off a junked '91 Stanza.
I paid $50 for the whole fan assembly. There was some trimming required to fit it in, and of course a complete custom wiring job. I had gotten used to having the dash switch, and the Stanza fans are multi-speed, so I designed and installed two control circuits, one switch with the dash switch and one with a thermostatic switch I installed on the engine bay wall where the airbox used to be. I designed the control circuits so that if either one of the switches is on, both fans run at medium speed. If both switches are on, they run at high speed. I also added a relay into the manual circuit so that I would not have the full 10-15 amps the fans draw running up under my dash.
The biggest benefit has been that the engine stays much cooler now when driving around town, especially in warm weather. The other big benefit was the large amount of room under the hood in front of the engine that was opened up with the removal of the stock fans and shroud. Any work around the front of the engine bay is much easier. It also freed up maybe 2 hp that the belt fan was eating up, and I know longer have that annoying whooshing sound of a fan clutch when it engages. I guess the project took a total of about 12 hours of work, that includes testing the fan motors to determine how the wiring worked and designing the control circuits.
Here's a shot of what it looks like now:

There's more pics if you go to http://www.v6-s12.com and click "Projects", but the pics on there are from right after I did it, before I put the relay in and cleaned up the wiring. it looks a lot better now, I'll put updated pics up there soon, including a new wiring diagram that includes the relay. I also plan to add a relay to the temp switch circuit this spring.

I highly recommend this modification for any car with a belt-driven fan.

Joel · Dec 3rd, 2003, 08:29 PM

Unless you have done everything else the money is better spent on a bigger radiator. Nissan clutch fans are quite efficient.

cls12vg30 · Dec 4th, 2003, 08:23 AM

OK, can you tell me where you can buy a larger radiator for 50 bucks, which is what the fan setup cost me?
They may be efficient for a clutch fan, but trust me a single fan sitting several inches back from the radiator cannot cool as effectively as two fans side-by-side right up against the rad. The amount of radiator area being cooled by the fans has effectively doubled, and the difference in the engine operating temperature is significant. And any engine driven fan will eat up a HP or two, it has nothing to do with efficiency of the clutch, it's just physics.
And in my case, a replacement radiator for my car is almost impossible to obtain. Last I heard Nissan had a couple left in inventory, they wanted $700 for one. No aftermarket ones exist.

Joel · Dec 4th, 2003, 11:14 PM

Oh so your electronic thermo fans run on free power do they? The losses from electrical load when compared to the frictional and inertia load of a clutch type fan work out to be about the same in the end. Both thermos and clutch fan do not operate when travelling at speed (the clutch fan slips freely and the thermo motors shouldnt be on at all if installed correctly) so its only at idle where you get any cooling benifit from thermos.

If you do a lot of city driving in the heat then sure they are a good idea but if you are looking to reduce running temperature for say track work or highway driving thermos wont do anything and a larger radiator is a better option.

And there is always radiators that fit. All you need is one with the inlet and outlet in similar places to stock. Make up custom support brackets if need be and scour the radiator hose bins at your local auto shop for a pipe with the correct bends. For example the top hose from a Mazda 1300 radiator fits perfectly on an SR20DET.

I will agree with you in that there is little chance of getting a radiator for $50 but with a bit of hunting around you could get one for $100?