Are Thermo Fans Better Options Than Running Standa

[AndrewD]

AndrewD,

Rotational intertia doesn't equal horsepower to clear that up.

The weight of the factory fan gone helps improve the engine accelleration a small amount, combined with other pulleys made of lighter material it all adds up to help more.

The weight of the fan on the end of the water pump pulley increases the load on the belt, which increases the fictional power losses.

The benifits you mention seem quite valid by the way.

Just to comment,

it takes more power (rate of work) to accelerate a higher rotational inertia item than it does a lower one. so yes while it isnt directly related it has an effect. The excess power required to drive the fan no longer exists, and can now be used to accelerate the crank and gearbox assembly.

I think you mean mechanical / accessory losses. friction losses would stay faily constant and only vary with changes in force.

[rev210]

you don't really notice at all if you just crawling through traffic or sitting still. The current draw on the big fans is under 30amp. It's only on when the airflow isn't sufficient at low speed, once underway it cuts out.

I found the 16 inch on the GTR got me a degree or two under the clutch fan temps as an average.

[Sumo]

I think most of the "load" the engine sees, in these high draining conditions is between the windings and magnets themselves; not the the increased idle RPM from the idle control stepper.

Altenaters do not have magnets in them, The rotor has a copper coil in it which the regulator controls the field current, the rotors usually draw a maximum of 4 amps, which depending on how the stator is wound will determin the output of it.

Next point is, an alternator's output is never constant, for instance a 100amp altenator about 70% of the time will probably be putting out 15amps just to run your accessories/ign/fuel pump. Once a car is started it no longer relies on the battery to run the accessories - this is all done via the alt. Especially on skylines where the battery is in the boot (got voltage drop?). Your electrical system loves 14.5v more so then 12v.

I know this is nit picking stuff but say headlamps for instance at higher voltage are not only brighter, but drag less current. Same with Thermo's and the like.

Light Globes example.

100w / 12v = 8.3amps

100w / 14.5v = 6.89amps

This is valid accross the board with most cars electrical accessories.

Cheers

Sumo

[GTR_STEALTH]

pfft..cbf reading thru all them pages.

I made a DIY on installing a thermo with temp controller on Ausrevs.

PLEASE NOTE THIS WAS FOR A VS BUT THE GENERAL INSTALLATION IS THE SAME.

Here:

Overview:

The clutch fan on your V8 is an integral part of you cars cooling system. However, sometimes installing an electrically operated thermo fan may be a better option.

Difficulty level(1-10):

5

Tools req:

Screw drivers

Socket set

Multi Meter

Crimpers

Beer

What to do:

1. Purchase a Thermo Fan Switch Kit and Fan itself from your local VPW, Autobarn, or REPCO.

Whats included in the kit & fan

The kit itself

2. Remove the old fan in your car by unbolting the 4 bolts. Be sure to replace those bolts into the pulley as they hold it in. Alternatively, if you decide to remove it altogether then a different belt to run the alternator is required and Electronic Water Pump installed.

Before

After

3. Remove the radiator OR simply remove the top hose, clips and slide it out enough to give you room to attach the fan.

Like this

4. Using the bolts provided, position the fan and slide the bolts through the radiator core fins. Be carefull during this stage as it is possible to damage the radiator.

(Note: Be sure to place the soft washer on the side that touches the radiator)

Refer to the next few pics:

This is how it should look once its properly secured:

5. Position the temp controller (with temp probe hangin off it) somewhere relatively close to the top radiator hose and make sure the bolt/screw is earth to the chassy. We chose to put it under the relay box.

Like this

6. Using the rubber with the slit down the middle (In the kit) place the temp probe into the hose and secure the hose to its normal position. Refer to these pics:

Note the rubber with slit i mentioned

7. Connect the appropriate wires, crimping them with spade connectors where app. And attach the relay securely. Refer to the next foto for detail:

Mounting the relay:

The wires crimped to the fan:

The wire to the top of the temp controller:

The wire to the Battery + :

8. Connect the grey wire to the bottom of the temp controller and splice it to a relay in your relay box. You need to use a multimeter to determine which wire to use. Simply turn you ignition to ACC/ON and find which one has power when its on and goes off when you turn your ignition to OFF.

You may need to lift the relay assembly which is acchieved by using a screwdriver in the two slots running along the middle.

Grey wire to bottom of temp controller:

In the next foto you may note that the wire we spliced it to is a fuse. This is incorrect! (It was late at this point! LoL) Use the relay marked 'F/Pump' or 'EFI' and determine which wire turns on/off with the ignition.

Spliced wire at the back:

At this point re-check that all wires are connected properly and to the correct place....Its now time to start the car.

Oh...and dont forget to top up your radiator!

9. Start the car and wait till it warms up. Determine when you want the fan to kick in, usually just below half way on the dash indicator. When it gets to your determined point, turn the tuning pot on the temp controller counter clock wise untill the fan turns on.

The tuning pot:

Insure that the flow of air from the fan is going the correct way -Into the engine bay. If not, remove fan assembly and flip the fins. Usually its a washer holding it to the shaft.

10. Turn off your car and insure that the thermo turns off also. If it continues to run when your key is in the position OFF, then you have not spliced the grey wire to the correct pin on the selected relay. Go back and re-check with a multimeter.

11. Brake out with the beers and enjoy.

-Erno

Edited October 27, 2006 by R33_STEALTH

[GTR_STEALTH]

Mods,

You may split the thread if you wanna turn it into a DIY for SAU...

Edited October 27, 2006 by R33_STEALTH

[carl h]

bah to electic fans, us s chassis swap guys have to use them and i hate them.

ive actualy relocated my radiator under my core support just so i could fit the std clutch fan again, i cant wait.

with e fans my coolant temps would never stabilize and tended to get hot in traffic, imho not worth it.