MyE28.com

I'm planning on running a centrifugal blower in my e28. I'm going tu use a 12 rib belt because at the boost levels I'm planning - 12 to 18 psi - I need to run a fairly small pulley on the SC.

That, in turn, gives me clearance problems with the radiatior. It's either the 12 rib belt or the fan, but not both. That got me wondering...

1. How about the stock electric fan in front of the AC condensor? Does that have sufficient flow to cool everything if it's set to activate at a lower temp? If so, has anyone got a source for a lower temp switch?

2. If the fan is insuffficient, what is a good source for a more powerful one?

3. Can a fan effectively cool the rad from in front of the condensor? Do I have to "box" both units to keep fan exhaust from spilling out from between the condensor and rad?

Any experiences/advice greatly appreciated.

Thanks...Steve5and6

I ran just the electric fan for a while ( with a high output aftermarket fan ) and gave up after dealing with over heating in traffic and when I drove hard. OK cruising on cool days. There is a reason for the big fan on the water pump and I didn't want to drop large dollars into a custom aluminum rad.

Enjoy the fan that BMW sent with the car,
Dave

My experience is opposite. My e12 has an aluminum e28 radiator. The fan clutch has been crapped forever. Even on the hottest days, the car doesn't overheat. I'm not going to bother buying another fan clutch, I'm going to get a nice thin SPAL electric fan and hook it up to a thermoswitch.

Makes sense, my TCD - S2 E34 puts pretty heavy demands on the cooling system, particularly with the A/C on in stop &go traffic. My intercooler rad is in front of the A/C condensor.

Cheers,
Dave

1. How about the stock electric fan in front of the AC condensor? Does that have sufficient flow to cool everything if it's set to activate at a lower temp? If so, has anyone got a source for a lower temp switch?

2. If the fan is insuffficient, what is a good source for a more powerful one?

3. Can a fan effectively cool the rad from in front of the condensor? Do I have to "box" both units to keep fan exhaust from spilling out from between the condensor and rad?

1. The stock setup is two switches, a low speed and a high speed. Low speed is what the fan runs at when the AC is on, or if the car starts getting hot. High speed only kicks on if you are really getting hot. You can get lower temp switches, I think I bought some a few years ago from BMP, or maybe BavAuto. What you do is move the stock low switch to the high position, and put a new extra low switch in the low position. The switch change will help, but the stock electric fan is not enough to cool the car by itself.

2. I have found some nice electric fans on eBay for very good prices. There are usually some OEM take-off fans on there, some are airflow monsters, the tricky part is finding a good one that will fit. Some even have two speeds like the stock fan.

3. If you have no room for a puller, then a really powerful fan and some sort of shrouding to make sure the air gets through the radiator will probably be needed. I don't know if the stock fan can do the job with better shrouding, it is not a bad fan but as installed by the factory it is really only good for the AC and as a booster for the main fan. I have had good luck running a single thin line 16" puller mounted without any shroud. It required a custom mounting bracket and had to be mounted very close to the radiator to get away without a shroud. It is very tight between the engine and radiator, as you are well aware. I don't know if you would have enough room to squeeze one in there with your pulley requirements, but it does take up less room than the stock engine driven fan.

I'd like to see D.C. electric motors drive variable pitch coolant pump impellers and radiator fan blades. Coolant and airflow would then be a function of engine temperature instead of engine speed.

The electrical loads could be decoupled from the engine under times of acceleration to shift the time domain of parasitic loss thereby increasing available horsepower.

Why tie engine coolant flow and radiator airflow to engine speed rather than engine load?

I'd like to see D.C. electric motors drive variable pitch coolant pump impellers and radiator fan blades. Coolant and airflow would then be a function of engine temperature instead of engine speed.

The electrical loads could be decoupled from the engine under times of acceleration to shift the time domain of parasitic loss thereby increasing available horsepower.

Why tie engine coolant flow and radiator airflow to engine speed rather than engine load?

Why, indeed? Many cars rely only upon electric fans, none of my cars keep their engine driven fans for long after I get my paws upon them. The electric water pump is the next step, and is being used already on a very limited basis, well except for the variable pitch part. I think regulating RPM is a better solution than a variable pitch impeller, the added mechanical complexity is not practical when it is so simple to electronically regulate the motor speed of the pumps.

In my pile of future projects I have an electric water pump and a thermostatically regulated PWM speed controller for it. Once I establish a baseline with the B35 conversion I am working on in the white car I plan on playing with the cooling system. Not that the stock stuff doesn't work fine, but for my own amusement. If the electric water pump works out, I have a couple of other ideas that would then be possible to try.

Specifically:

1. Since I'm likely going to be using a 12 rib belt to drive a centrifugal supercharger, I won't have room between the pulleys and the radiator for any kind of fan, even a slim electic one. My question is, has anyone tried to build a box around the AC condensor and radiator to keep the fan exhaust from escaping between the two and not cooling the radiator? If so, did it make a difference?

2. Supposedly, shrouds are important for efective fan cooling, however, a front mounted shroud sounds counterproductive. ANyone have good idea on how to optimize front mounted fans?

2. Has anyone tried to relocate the radiator forward to gain more engine-to-fan clearance? It looks like the radiator could be mounted on the front of the radiator bulkhead. Has anyone tried this?

Thanks...Steve5and6

i've used spal fans on a couple different cars, they work great. you can get very thick high cfm fans, or really thin fans.

keep in mind the fan doesnt have to be centered on the radiator, on my 3 rotor, i had one small fan and one big one, due to the water pump pulley being off center.

black magic makes fans too, but quality is poor.

also keep in mind the larger the radiator, generally the less fan you need. the radiator can mount anywhere theres air flow, or you can do what audi does and just add another bonus radiator somewhere....

also since the car has fan wiring, you can use the factory fan switches/wiring, you probably want to run the power thru a relay and a fuse, but the triggers are already there
mike