E30 Zone

I've been reading on the net that there's a small fuel economy improvement to be made by replacing the viscous fan with an electric item.

I'm just wondering if anyone has done it and whether they found and difference.

yeah i have an eleccy fan. not much difference really, but is generally better wiht the electric and keeps the engine temp under control better in traffic etc. You can just notice a bit less drag when pulling away, that's the only difference in terms of driveability.

Engine bay looks nicer and sounds quieter

i fitted one to mine and it hardly ever runs! only when i'am reversing up the drive after quick thrash home and the temp needle only just goes over half way! but i do have a brand new rad in there

i also fitted a manual bypass switch on mine and put it next to the heated rear windo switch so i can put it on in readyness of quind traffic or a trackday.....

anyone got any ideas of where to get one of these, ie a kenlowe or do other applicattions fit

there is an arguement that by cancelling your viscous fan you then need to make the alternator work harder to run the electric fan thus there cannot be any perfromance/economy gains, the only real and proven advantage is you can switch it on more accurately with a calibrated temp switch.

and yes the engine bay looks nicer!!

mrLEE30 wrote:you can switch it on more accurately with a calibrated temp switch.

But, controlling the engine temperature is not the job of the fan!
Engine temperature is set wholly by the water thermostat. The purpose of the radiator, and any arrangements to cool the radiator, is to provide a resevoir of cool water to enable the water stat to do its job.

mrLEE30 wrote:there is an arguement that by cancelling your viscous fan you then need to make the alternator work harder to run the electric fan thus there cannot be any perfromance/economy gains

yes, but to pick up on this bit too, the electric fan should only ever come on in traffic etc, so the alternator is only working harder in traffic etc when the inlet temps are sky high etc which will have a much bigger impact than this. On the open road the fan will always be off and thus it will presumably have a (admittedly small) performance gain.

The alternator output in traffic may well not be able to keep up with the electrical load demanded of it, and the battery may partly discharge. The alternator will still be imposing a load on the engine to recharge the battery after you hit the open road, whereas the viscous coupled fan would just be idling.

haha yeah i spose that may be possible, but even if so, as the car has been in traffic, it will take a while for the IAT to drop back down to sensible levels anyway and give you decent power, by which time I'm sure the battery will have recharged. I actually retard ign based on IAT on mine too - in short, when in or just out of traffic, performance will not be optimised regardless of the electric fan. I guess the bottom line is that the fan never comes on during normal driving, so under normal conditions will have no impact on performance, whereas the viscous fan will have a marginal impact.

I could argue that at high speed in a high gear, the forward motion of the car causes enough airflow over the fan for it to act like a turbine and actually add to the engine's power!
I think we both agree that any gains from fitting an electric fan will be at best, very marginal, and, because of the reliability issue, I would refrain from doing so, except in the case of cars like my M50 engined E30, where there is insufficient room to fit the mechanical set up.

Brianmoooore wrote:I could argue that at high speed in a high gear, the forward motion of the car causes enough airflow over the fan for it to act like a turbine and actually add to the engine's power!

you could, but it would be rubbish!

I think we both agree that any gains from fitting an electric fan will be at best, very marginal, and, because of the reliability issue, I would refrain from doing so, except in the case of cars like my M50 engined E30, where there is insufficient room to fit the mechanical set up.

sure do! I've found that the viscous fan did a rubbish job of keeping everything in check in traffic though and prefer the electric fan, which has more effect in traffic. Is a bit noisy though!

Brianmoooore wrote:

mrLEE30 wrote:you can switch it on more accurately with a calibrated temp switch.

But, controlling the engine temperature is not the job of the fan!
Engine temperature is set wholly by the water thermostat. The purpose of the radiator, and any arrangements to cool the radiator, is to provide a resevoir of cool water to enable the water stat to do its job.

tut tut mr mooore i said it can be switched on more accurately, i did not mention its ability to control engine temp

Do I hear antlers clashing, is a young buck staking a claim to Brians throne? Will Brian be walking off into the woods alone or will the contender skulk away licking his wounds. Watch this space!!!

well it might be something i might do for mine, at some stage, but the main reason for asking was in regards to my old mans e36 328i

I think the main reason for the performance gain/fuel saving is that the viscous fan is partially engaged at all times, whereas the electric fan will only come on when needed.

Isn't the fact no new cars run a viscous fan important here? The reason they are not used is because of the recognised economy issues and the fact electrical fans are extremely reliable, ive only had to change one myself. An electrical fan is on my list to do!

VAG cars do still use a viscus fan, ive only had dealings with an 04 plate passat TDI and that had the viscus and an electric fan for the air-con

BillyWiz wrote:Isn't the fact no new cars run a viscous fan important here? The reason they are not used is because of the recognised economy issues and the fact electrical fans are extremely reliable, ive only had to change one myself. An electrical fan is on my list to do!

Most new cars don't run viscous fans, because the engine has been stuck in sideways to drive the wrong wheels, and therefore any rotating pulleys are nowhere near the radiator!

BillyWiz wrote:Isn't the fact no new cars run a viscous fan important here? The reason they are not used is because of the recognised economy issues and the fact electrical fans are extremely reliable, ive only had to change one myself. An electrical fan is on my list to do!

Most new cars are front wheel drive with the engine the wrong way round to drive a fan, leaving an electric one as the only option.

I've had a car where the electric fan failed in the middle of summer in London traffic, had to have the heater on full and all the windows open, was a trifle uncomfortable !