Electric fans: 2 smaller or 1 bigger?

[jlevie]

I've used a 16" fan rated at 1800 which was barely adaquate here in the South under race conditions. It made no difference whether it was mounted as a puller or pusher. I'm currently using a 16" SPAL puller rated at 2300CFM and it have proved to be more than adaquate even under the worst conditions. I didn't use and shrouds for any of these.

One word of advice, mounting the fan directly to the radiator core (the easiest) can result in the mounts eating a hole in the fin tubes. I'll leave it as an exercise for the reader as to how I know that. Okay, two words of advice. Use a thermo switch that trips a few degrees above the thermostat rating for automatic operation. With the standard 80C stat an 82-83C thermo switch works great. The aux fan thermo switch trips too high (low at 91C, high at 99C)

[dandrewg]

I've used a 16" fan rated at 1800 which was barely adaquate here in the South under race conditions. It made no difference whether it was mounted as a puller or pusher. I'm currently using a 16" SPAL puller rated at 2300CFM and it have proved to be more than adaquate even under the worst conditions. I didn't use and shrouds for any of these.

What part number SPAL fan are you using? I'm using a 16" SPAL puller 30100400, which bimmerworld recommended for an M20 and I didn't think it was rated that high.

[jlevie]

The fan I have is part number 30102120 (2360CFM). The rating for a 30100400 is 1300CFM. There is a chart showing the SPAL fans at http://store.bimmerworld.com/spal-el...ans-p1160.aspx.

[dandrewg]

Did you have to modify anything to get the 30100400 to fit between the engine and radiator? It appears that my water pump pulley bolts are pretty close with my slim 30100400 fan.

[jlevie]

A 30100400 is the largest fan that can be used if you center the fan on the radiator. You can fit the 30102120 by offseting the fan to the left as far as it will go. And you need the fan mounted close to (but not touching) the radiator. I'd have to check but memory says that the forward edge of my fan is probably 1/4" from the radiator. The fit is tight, but it works. That is if you are using a puller. With no A/C, you can center a pusher in front of the radiator.

[CorvallisBMW]

I'm running the 30102048 (High Performance Fan - Push, curved) on my m30 swap with A/C. Keeps everything in check even on 90*+ days. God knows the m30 makes twice the heat as a 24v swap.