First, thanks everyone for the replay on other recent questions I have ask.

Question. Is the Auxiliary radiator fan necessary? Primary mechanical fan is deleted. Would the 2 or 3 minute trip through paddock, post session, be too much with very little air flow, do to low speeds and everything heat soaked? If the answer is “keep the fan”, do you use the sensor switch or a toggle in the cockpit? Use OEM or aftermarket pusher?

Background: 99 M-Coupe S52. Built for NASA TT and the new PT. Both allow for any mod, you just take points for each mod and the list is very long. I removed the AC last night. To do so, the auxiliary fan needed to be removed. 3 of the 4 mounts for the fan are on the AC condenser coil. So after it was all out, I was observing how unobstructed the path to the Radiator is without the Fan and Condenser. Where is the balance between nice track air flow and needing a pusher fan in the pits?

First, thanks everyone for the replay on other recent questions I have ask.

Question. Is the Auxiliary radiator fan necessary? Primary mechanical fan is deleted. Would the 2 or 3 minute trip through paddock, post session, be too much with very little air flow, do to low speeds and everything heat soaked? If the answer is “keep the fan”, do you use the sensor switch or a toggle in the cockpit? Use OEM or aftermarket pusher?

Background: 99 M-Coupe S52. Built for NASA TT and the new PT. Both allow for any mod, you just take points for each mod and the list is very long. I removed the AC last night. To do so, the auxiliary fan needed to be removed. 3 of the 4 mounts for the fan are on the AC condenser coil. So after it was all out, I was observing how unobstructed the path to the Radiator is without the Fan and Condenser. Where is the balance between nice track air flow and needing a pusher fan in the pits?

A lot of the I-Prepared racers use a puller fan only. The Spal ones which you can get through Bimmerworld and other places work well. You can probably get away w/o a fan but why chance it on an engine that is known to eat headgaskets when it is over heated?

Carlos.

i use a spal pusher on my j-prepared car. works great, light and since it is in front of the radiator, it leaves a lot of room between the rad and the engine for maint, etc.

mine is connected to the stock temp sensor switch.

ditto sourcing through bimmerworld. between the spal fan and the pwr radiator i got from james, cooling is not an issue...even in the humid, 95+ deg summers in the midatantic.

marshall

i havent had a fan on mine since last april, I ran Roebling in June and never had even a slight rise in water temps, trick is not to idle the car in the pits for a long time, and get a GOOD, ie.........not the OEM water temp gauge

I have NO fan, not AC aux or the engine fan, stock thermostat too

I deleted the engine fan on my car and ran w/o problems for about 4 track events. I used the a/c fan while the car was idling for any period of time. During my last event at VIR a few weeks ago, I had coolant blowing out of my radiator cap. I've replaced my cooling system and now run a SPAL puller fan.

Dan,

For a dedicated track car, I would say delete it, then get a removable shroud/fan that you can use in the paddock if needed.

A BMW engine is not at all tolerant of overheats. Just one good overheat has been known to fail a head gasket. So it is better to err on the side of caution and provide more cooling than necessary than it is is to risk losing a head gasket. You can buy lots electric fans, relays, and thermoswitches for what one head job costs.

if you delete the engine fan, replacing it with a SPAL or similar puller type fan is the safe approach. If you have a real water temp gage one can manually control the fan. But if you forget to switch on the fan... Better to include a thermoswitch in the installation to automatically turn on the fan. BavAuto and others have an 82C thermoswitch that can be used for this purpose.

I overheated a track-only motor at the track because of a dead aux fan. :( Just pulling around the paddock too.

On my former JP E36 325i, I removed the AC, condenser, etc and remounted the aux fan powered by a new toggle switch. I removed the main cooling fan. Never had a problem. The weight of an aux fan or aftermarket fan is minimal and much cheaper than a head gasket.

The C Mod E36 M3 LTW had no aux or main fan and we finally popped a head gasket... a new pusher fan has been added. The fan was always on my to do list, just never got around to it. My bad.

BTW, the temps can climb in the paddock or durng a red flag. I was suprized the temps I was seeing.

Vince

Thanks every one for input.

Based on replies and the more I go over it in my head, I think the smart thing is to have a pusher fan. The small amount of additional air passing through the radiator on track is not worth the risk of high temp fluctuation and gasket failure. A pusher will leave room for thicker radiator if I upgrade some day, and also protect fan motor from the hot radiator blow through. I do have a real water temp gauge, well it’s in the pile of stuff to be installed. I will use a tstat switch and an over ride/backup toggle. It’s only money right?

Thanks for the input. :buttrock

How much did the AC stuff weight that you pulled out?

I'm sorta close to a point of no return on my coupe, just sort of wondering. I do still drive it on the street as I don't have a tow vehicle though. :(

The condenser coil is maybe 6 or 7 pounds but it restricts the air flow to radiator big time. The compressor is surprisingly heavy. It must be nearly 20 pounds. Compressor mount and tension pulley 5 or 6 lbs. Plumbing another couple pounds. The evaporator is maybe 5 pounds and dryer is maybe 2 pounds. The weight is fairly high but my real reason to pull was to get the condenser coil out from in front of the radiator.

Hard to justify ripping up a good coupe. Project99 was an insurance total. I got it for cheap. Only damage was drivers seat but insurance company could not get the extinguisher dust out of the car. I stripped the interior and that white stuff is still floating around.

I first took out the mech. fan and left Aux fan switched to come on. Had some cooling issues, removed AUX fan and put mechanical fan back on...

Y not just use the mechanical fan? Its perfectly fine to use and doesnt block airflow at all.