convertible 63

Good morning?!? Ladies & Gentelmen
Claudia & me own a little collection of vintage cars.The old cars got rotation speed dependent fans (rsdf).Those fans do need a lot of capacity from the engine power,are noisy and need quiet a bit petrol.They are working every second that the engine runs! Electric fans do need about 30 watt.In town they are needed just 30-40 % of running time,on the "fast speed" roads they are on homopolar(New,very important word to me) power.The head wind is
sufficient.Has anybody got facts or an idea how much capacity a rsdf needs in hp about?A swap in my Triumph Spitfire could be really usefull.69 hp are not that much to get wastet for nothing
Thank you all,Claudia&Martin

Oldsguy

This subject has been debated before, if not here, on other forums that I frequent. Basic laws of physics state that energy is never expended, it just changes states. So which method is more efficient? I don't know but I prefer mechanical fans, especially for our older cars, it just seems to fit. For your little spitfire, you may be better off using electrical fans as they are usually smaller and quieter as you noted. But I still am not sure if you would end up being more efficient though.

oldcutlass

I believe HP loss for a mechanical fan is dependent on how much toque your engine produces. Overall lets say 5-10 HP. Then you have to consider the additional load on the alternator or generator which would also sap some HP 1-3 so net you may realize 4-7. As far as noise, that's a wash as the electric fans are just as noisy. The other thing to consider is mechanical fans are pretty much maintenance free, electrics have multiple failure points and are much more complicated.

Personally MPG is not a good reason to go to electric as the payoff is minimal. If your trying HP where tenths of a second matter, then yes electric is worth considering. It has been proven time and time again that you can easily shoot yourself in the foot by going to an electric setup only to find its not as good as the stock mechanical.

Koda

Bear in mind that a squirrel cage blower motor for your furnace is often a quarter horse. I would guess a fan needs 1 or 2 HP to push, and it's bolted to the water pump so no extra drain due to belt drag. Electric fans are there for cooling when the engine is off, extreme racing power savings, and for cars with traverse engines.

joe_padavano

Dredged this thread up after nearly a decade???

oldcutlass

Dooooh, it started with a hijacked post. Did not even realize it was a very old thread.

redoldsman

I just thought you might have been tired from that drive back from the Zone Show yesterday.

oldcutlass

God that was a long drive...

rustyroger

First off I know it's an old thread.

Howeaver I don't agree on couple of your points (other) Eric.
Mechanical loss due to the fan (and on an old European car almost certainly it would be a fixed fan) would be in proportion to how much air it is shifting. Unless the fan is wired permanently on with the ignition, noise should only be an occasional issue if the car isn't moving.

If the fan is drawing 6hp that's around 10% of a Triumph Spitfires maximum power, so a significant improvement in fuel economy is quite likely. Don't forget the op would be thinking of European gas prices.

Electric temperature controlled fans came to the fore when fwd became popular, most cars leaving the factory with such a system, some rwd European cars also had a factory electric setup, the Fiat Mirafiori from the 1970's being one example.

Roger.

Tedd Thompson

And every one of the million Miatas every sold run on two electric fans and they aren't noisy at all. Common conversion on many small sports cars..... Tedd

oldcutlass

Its a good discussion, too bad we didn't have it with the op. Standing next to 2 cars idling, 1 is a car with a mechanical fan and the other with electric, which is noisier? The electric. Roger I agree with you and my second paragraph was pertaining more to our old V8's.

Yellowstatue

Would an electric car have an electric fan or a mechanical one?

oldcutlass

I'm not a "fan" of electric cars.

rustyroger

Let's see who can be the most pedantic here.

I guess the electric motors would have a fan to cool them, so It would be a mechanical fan driven by an electric motor.

Roger.

rustyroger

Most rwd American and large cars from the rest of the world utilised clutch fans to get adequate cooling when idling, but limiting noise (and I dare say mechanical losses?) when moving. Back in the 1970's the Rover L6 engines were prone to the clutch fans seizing, we could always tell when one came onto the shop from the noise under the hood!.
When were clutch fans first introduced on mainstream cars?.

When petrol prices shot up in 1973 all kinds of snake oil economy aids were being peddled in the UK, none of which improved fuel economy on a properly tuned engine. Except electric fan conversions, which if set up properly showed improvements on most cars, enough to show a profit on the outlay over around 20k miles.

The BMC fwd cars from the 1960's had fixed fans, with the radiator mounted in the left inner fender. Some Renault cars with the transmission in front of the engine had the fan driven by a take off from the camshaft.

Roger.

olds 307 and 403

Good electric fans cool well and are cheap at wrecking yards, certain models fit our cars. What isn't cheap or reliable are fan controller's, relay's and thermal switches, they all fail. There are US made controllers that are expensive and basically custom made worth buying. I like the fixed factory 4 blade fan that is factory on my 70S. I could use a shroud with it but still keeps me below 190 for the most part with my 2 core copper rad. I know one guy went from a 5 blade clutch fan to that fan and his 403 runs much cooler now. My understanding is that fan pulls a lot of air, doesn't steal a lot of horsepower due to design and has no parts to fail.

rustyroger

Electric fans have been almost universal on most mainstream European cars for many years now. Mostly they are very reliable, which given some makers spotty overall reliability reputations is noteworthy.
I'm not suggesting they are bombproof, and they add to manufacturing costs, but in the main are relatively trouble free.

It would take quite some money and time to compare your cars, or your friends 403 powered car, power gains or losses under controlled identical conditions with various types of fan.

You run yours without a shroud????. How dare you sir!. Everybody knows taking the shroud off will cause havoc with your cooling system!. Don't let your car know it should have a shroud, it will promptly start overheating.

Roger.

olds 307 and 403

Yah, being a factory, non A/C car, Olds thought shrouds were only for lazy, fat people with A/C cars. I am surprised it has done as well as it has with a 2 core rad that was recored, maybe more fins per inch. Why they wouldn't just add a 3 core replacement at that point, is beyond me, seeing as the tanks are the same. It sucks that the 70 shroud is so expensive, even compared to the 71 or 72 shroud but is on my long list of items to buy.