bwirolla64

What is recommended for a fan temp sending unit? If I have a 185F(86C) thermostat should it be a 195F on 175F off or 185F on 165F off? Thanks

Pop N Wood

iTrader: (1)

I like having the fan on and off temps higher than the thermostat setting otherwise once they turn on the fans never shut off.

JetMech442

iTrader: (1)

You want the Radiator to be able to do it's job before the fans kick on. Once the thermostat is full open(185), the radiator gets full flow which enables the most heat transfer w/o fan power. Ideally, you never want the fans to bring the thermostat below stat full open temps-this causes stat cycling(unnecesary wear), and unnecessary thermal gradients.

Stage 1 should come on around 195 and off at 190(this prevents fan cycling), and stage 2 on at 200, off at 190.

This strategy allows 5 degrees for the radiator to do it's job before the fans come on, say in traffic or idle(fans shouldn't need to come one during these events). I have an aluminum Be Cool radiator which is very efficient at controlling temps in traffic, cruising etc. and an 02 dodge viper cooling fan(Stage 1 2000 CFM, Stage 2 4000 CFM) for when things get hot.

If you find that the when the fans shut off at 190, and the temp climbs right back up to 195(fan on again), you could drop the fan off temp to 186, which would allow more time between fan events and maybe give the radiator a better fighting chance.

Every cooling system is different, radiator efficiency, fan power(multiple stages), underhood temps due to headers, turbos... This is meant to be a guide-- my engine is an 05 LQ9, 228 TSP cam, long tubes, LS6 intake, 98 corvette WP, dodge viper fans, and be cool radiator in a 69 442.

I hope this was helpful and clear. Please ask any questions if I can clarify any of my meanings.

bwirolla64

Well I have a Be Cool radiator as well with the dual SPAL fans and it comes with a 195 on/175 off. They offer a 185 on/165 off as well as a 210 on/ 190 off. I looked up the fans and they are 2,719 cfm @ 0 static pressure which is its highest cfm. From reading both responses Wood would suggest the 210/190 and 442 would use a 195 but off at 190
So if I can get the 210on/190off that would work? Or is there another sending unit you would prefer? Is it also a possibility to run two sending units with one per fan at different temps? thanks for the replies

JetMech442

iTrader: (1)

The 210 /190 will work just fine. I prefer to keep my temps in a narrow range, but the LS motors were validated at 210+ normal operating conditions.

I wouldn't want the fan to turn off below my stat full open temp, becuase the fan will be trying to drive down temps and then the stat will reduce radiator flow to increase temps. No need to have them battling it out-this just wastes mpg's.

My fan has two speed settings, not sure if yours does or not. If it does, I would have it come on 215-220 since you don't want coolant temps much higher than that.

Oh, and your ecm can control fan on/off temps-thats how I made my fan strategy. I'll stop posting for a while and see if anyone else chimes in.

Pop N Wood

iTrader: (1)

Just put in a 160° thermostat.

Actually i would go with the 160° thermostat and the 195/175 fan switch. That way your fans will almost never run while you're moving.

Old Geezer

iTrader: (3)

Can't you control the fans w/ the pcm?

bwirolla64

These fans are wired separate from the PCM. They are made for a 64 impala so they run when the sending unit tells it to. I also don't have my wiring harness yet so I don't know how that is wired