Which Fan?

[Dave81]

Chaps,

Whilst looking around at various sources in relation to cooling, one of the common threads is Viscous vs Rigid vs Flex vs Electric.

A few people have claimed (with apparent proof), that there a decent HP gains to be had by moving from a Rigid setup to viscous.......even more if you go the whole hog and install an electric setup!!

Currently I'm 99% sure that I have a rigid setup on my car.

Not sure of the flex as many criticise them for fatigue and fracture over time and expensive reapair bills!

Electric looks expensive considering the overall usage of the car (not daily and uk temps).

What are the thoughts on moving over from a rigid to a viscous fan with thermal clutch?

What I have read is HP benefits, less load on the waterpump and other bearings at high RPM or low temps......In short not many negatives!

Looking for thoughts and experiences from the knowledgeable please.................?

[autofetish]

Get down the scrap yard and take a electric fan off anything old ish

nothing very modem as may use pulse width modulation to control fan

most peugeot run a nice due fan set up which is nice

rember relay it at wiring time.

And do a (Jim) remember to switch it on

[Dave-R]

People think an electric fan uses less HP to run than a conventinal fan.

I can't see how that could be possible when you think of the physics of it.

Stick with the fan you have got. If you are looking for something to do then look at ways to make the electrical system more efficient with fewer losses. That will release more HP than a fan change.

[Dave999]

all of em work

all of them rob power

alternators are mighty hard to turn over when running at full pelt. and electric motors especially when being subjected to some kind of resistance to turning drink current

for a standardish rpm range nout wrong with the standard fan and water pump

infact they'll last 100,000+ miles and don't have a life measured in 1000s or 10s of 1000s of hours.

simple and works

peugeot 406 coupe diesel fans can be had for £20 handy if you want to drive an external oil pump mounted on the timeing cover driven direct from a drive bolted to the end of the cam

like this....no fan space then

[Les Szabo]

Well all I can say Dave81 is that anything you remove from the engine that requires it to drive a unit will increase HP some, I never ran an alternator either, and had an MSD unit, obviously you can't do that on a street car, an alternator can be worth as much as a 1/10th in the quarter.

However, the priority here, as always, is a strong ignition system with good leads and good plugs with the proper ignition curve in your dizzy, total advance, carb etc., get everything set up pucker and running on song and the difference in a clutch fan, will be negligeable, but it won't hurt.

Les

[Dave-R]

The no alternator thing will give more power for sure.

Take a mechanical fan that moves x amount of air for y amount of power from the engine. The losses from the engine are almost all due to the air resistance of the fan yes?

Now mount an electric fan instead. Assume it is designed to move the same amount of air. It is going to require exactly the same amount of HP to drive it.
So where does that come from?

It comes from the alternator that is being driven mechanically from the engine. Only now that mechanical energy is being converted into electricity (with losses), then sent to the electric fan motor via wires (and losses) to be converted back into mechanical engergy (with losses).

So it actually robs more HP from the engine to run an electric fan that moves the same amount of air as a mechanical fan.

You cannot create or destroy energy. You can only move it around and every time you change the type of energy there are losses.

[Johnny Dart]

Looking for thoughts and experiences from the knowledgeable please.................? [/quote]

I'm changing mine( when I've done all the other stuff) over to electric, with a fan switch mounted in the rad,or you could use a ebay fan switch housing in the top hose. you can wire it to be fully auto , as I will be, and if you want wire in a tel tale light on the dash , so you can tell when its operating.
80% of the time in the UK it wont be needed,so won't be on = quicker warm up time and less engine wear.
I vote electric

[Blue]

Do yourself a favour and get a mopar performance viscous fan package, job done. The trouble with electric fans on V8's is airflow, you need in the region of 3000cfm, a viscous fan shifts loads more air than most any aftermarket electric fan. You can fit something from a late model car with a V8 that will do the job, but they pull a load of current so you need an alternator with good output or you'll be flattening the battery in traffic. An alternator working hard also robs power. I've tried to go electric in the past and failed, even with a huge ally rad. Ended up with a viscous fan, no shroud and a 22" rad, problem solved, even kept my 511 at 185 degrees in traffic.

[Bozwell]

People think an electric fan uses less HP to run than a conventinal fan.

I can't see how that could be possible when you think of the physics of it.

when moving along fan not needed so no drain on engine when power needed.

when staitionary fan on where the extra power drain wont make a blind bit of difference in performance

[Dave-R]

when moving along fan not needed so no drain on engine when power needed.

when staitionary fan on where the extra power drain wont make a blind bit of difference in performance

In theory.

But I never made a single run up the strip without it wizzing away. The only time you are going to notice the fan going off and on is when cruising and don't need the power.

I think my electric fan was something like 2300cfm (which is big) and it only just coped in hot weather along with several modifications to increase airflow to the very efficient alloy radiator I had.

The only good thing about an electric fan is you don't have to worry about getting your hands or your timing light wires caught in it. Which actually for a clumsy git like me was probably the best option. But I wouldn't use an electric fan again unless I had to.

[Bozwell]

But I never made a single run up the strip without it wizzing away.

you could have turned it off.

[cadboy]

Mine is set up with 2 off 12" fans and I would chnage back to standard as the electric fan set up is not that good.

I will look into Blue's viscous fan, thanks blue.

[Bozwell]

also be wary of so called race radiators as they are designed for high speed airflow so will be rubbish for cruising car shows etc.

[Dave81]

Thanks for the input Chaps.

I have no cooling issues, but for my own sanity, i'll be getting the Rad recored as part of the cooling system overhaul this year, with new hoses and thermostat............this is just the next additional step.

Anything that will lower mechanical stress and add HP over the rigid setup, then why not!

In relation to electric, i like the idea, but would not add to the vintage wiring on the car. I will be rewiring with a painless kit in the future, so may look at that at that stage........This will probably be around the same time as paint, so i'm talking at least 12 months away!

Blue,
Was on FABO yesterday and dug into the history of such topics........loads of guys on FABO mentioned the Mopar Performance kit, hence why i asked regards viscous with thermal clutch (as thats what the MP kit is).

I see Summit are doing them for circa $115 + shipping Cadboy!

More thought required........Would you change out and upgrade the waterpump at the same time??

[Mossy68]

Thanks for the input Chaps.

I have no cooling issues, but for my own sanity, i'll be getting the Rad recored as part of the cooling system overhaul this year, with new hoses and thermostat............this is just the next additional step.

Anything that will lower mechanical stress and add HP over the rigid setup, then why not!

In relation to electric, i like the idea, but would not add to the vintage wiring on the car. I will be rewiring with a painless kit in the future, so may look at that at that stage........This will probably be around the same time as paint, so i'm talking at least 12 months away!

Blue,
Was on FABO yesterday and dug into the history of such topics........loads of guys on FABO mentioned the Mopar Performance kit, hence why i asked regards viscous with thermal clutch (as thats what the MP kit is).

I see Summit are doing them for circa $115 + shipping Cadboy!

More thought required........Would you change out and upgrade the waterpump at the same time??

Dave. Just freshen her up and get her on the road mate. You'll prob have a few teething probs to sort throughout the season then sort out upgrades over winter !