I know engines run best at certain temperatures, hence the reason a manufacturer uses a certain spec thermostat.
The GTO LS2 uses a 186 degree thermostat, so for a while I've been setting the fan to come on a little above that. I think that's a mistake and I should see what the GTO used as a fan set-point instead. I'm sure it's more in the 200 range.

I've got quite a large aluminum radiator and very good single fan setup that I've run in the car since my old iron small block days and it struggled to keep the old iron cool on hot days.

Not the case anymore! On the hottest day the LS will stay in the 180-190 range, even at idle. I don't think I've seen the Temp gauge at 200 more than once. I verified the coolant temp showing on the gauge to what the ECM sees and they're the same.
I'm running the factory cowl hood that's open at the back (no flapper or any baffling) so it's breathing cool air off the windshield in gulps.
I adjusted the fan controller way down so it doesn't come on till the coolant temp is a lot higher, but then Fall hit and the outside temps dropped.

Should I swap for a smaller radiator? Keep adjusting the fan controller to the bitter end and let the engine get hotter? Even with the fan off, I'm in the 190 range.
Too much cooling?

Thanks!

 

I have a giant BeCool aluminum radiator in my 1970 GTO and it was necessary when I was running a 502 bbc. I run a stock thermostat in my 6.2L, which I think is 205 degrees? The fans kick on around 210. It takes a good 5 minutes sitting at idle for the fans to come on and as soon as I move they shut off. On the highway my temp gauge is pegged at about 190, like yours is. I just don't worry about it.

Andrew

 

I'd set the fan to about 210 and leave everything else alone, you're thinking to much.

 

I agree, you can't have too big a radiator. The magic is the thermostat, this is what actually regulates the temp.

 

They put the high temp thermostats in for smog reasons. You will make more power with cooler temps.

Agree with above, the only possible disadvantage of the radiator being too big is added weight. The thermostat regulates the engine temp. A bigger rad means you might not need to run the fans as much, so that is good.

 

Man i wish i had this problem!! lol. I watch my temps rise to 212 till it boils out of the surge tank!!