[trav3000]

I have a '95 325i and was thinking of switching my stock shaft driven fan for an electric one. what do you guys think?

thanks,
travis

 

[C Sean Watts]

I have a '95 325i and was thinking of switching my stock shaft driven fan for an electric one. what do you guys think?

thanks,
travis

In Texas, you might benefit. BUT, it will all depend on your driving conditions and what the electric replacement will do as far as CFM rating. If you find an electric with no lower a CFM than the belt fan and a very good (nearly sealed) shroud... Since you are where you are, do NOT let anyone tell you a "fan delete" is a good idea.

 

[trav3000]

cool, thanks. so you think the stock fan is more efficate?

 

[jason_recliner]

In terms of efficacy, you're down to the CFM as C Sean described.
If you're talking efficiency, an electric fan has to take the original mechanical rotation, belt/pulley it to the alternator's speed, convert it to electricity through several forms, store it, retrieve it, then convert it back to mechanical rotation. Thus lots of losses in the line.

For effectiveness, I could be wrong but I doubt we're talking sheepstations with the real world values here either way.
I've always understood you only need the fan at idle anyway. It's just in the air's way on the highway.

 

[trav3000]

thanks guys, after talking to you i think i'll just stick with the stock fan.

 

[E36 Phantom]

Well, an electric one is nice to get the draw off the engine. But they're pricey and you need a good one. Of course, the mechanical fans are known to explode occasionally, too. Details, details.

 

[jason_recliner]

Well, an electric one is nice to get the draw off the engine. But they're pricey and you need a good one. Of course, the mechanical fans are known to explode occasionally, too. Details, details.

I've heard this. But I don't understand how it can be. The power has to come from somewhere, and that's mechanical loading on the alternator. Plus total losses. So for the same mechanical "air pushing" blade power available, there's a larger engine load overall.

The voltage regulator will cut in and out as required; you don't get to choose when.
I can though see how an electric fan (or lack of a constant mechanical one) allows the engine to rev up at a higher rate - as long as the alternator is not heavily loading at that time.

I don't think the maths add up. If I'm wrong I'd like to learn how it really works.

 

[Bmwcat]

FWIW the area I live in has summer days reaching 110 degrees sometimes and the stock cooling system has never had a problem. My .02c worth.

 

[C Sean Watts]

I have a '95 325i and was thinking of switching my stock shaft driven fan for an electric one. what do you guys think?

thanks,
travis

TRAVIS,

If you need to replace your fan and clutch I'll rent you the proper tools to do it. If you want cooler running, put in the lower temp. thermostat, temp switches, then get a bore scope or very small mirror to look inside the radiator. If you see ANY hard scale/ceramic layer build up AT ALL, replace the radiator. If it's soft scale you can scrape off easily, go to a Mercedes Benz parts counter and ask for "citric acid flush" and follow the directions to a T. You will still come out spending less money doing it correctly.

 

[C Sean Watts]

I've heard this. But I don't understand how it can be. The power has to come from somewhere, and that's mechanical loading on the alternator. Plus total losses. So for the same mechanical "air pushing" blade power available, there's a larger engine load overall.

The voltage regulator will cut in and out as required; you don't get to choose when.
I can though see how an electric fan (or lack of a constant mechanical one) allows the engine to rev up at a higher rate - as long as the alternator is not heavily loading at that time.

I don't think the maths add up. If I'm wrong I'd like to learn how it really works.

You are not wrong. The power does have to come from somewhere and it's NEVER free. There are a scant few electric fans that move as much air as the belt driven one and they are NOT cheap. In purely design terms, the benefit of the electric fan is space savings.