What temp is this LS thermostat?

[Steve1968LS2]

I found one site that said it's 212-degrees, but I want to confirm.

The PN is 12581594 and it's refered to as a two piece unit (housing and t-stat).

If it is 212 then I would like to drop down to a 180. Right now the car stays around 210ish at idle.

[Chris442]

I think I remember seeing it was 187* one time. I'm not sure if that was for the one piece or the two piece, though. If you take into account the typical 15* difference between the rating and what the engine operates at, that seems pretty close to what they usually run at.

A 180* couldn't really hurt anything IMO. It seem to be about ideal for an LS motor.

There's not much point in going to a 160* in these motors as they like to run a bit hotter. I lost 1 mpg in my LS2 goat dropping to a 160* from stock, so efficiency was definitely down.

If you have a late model stock computer, the fans can't be set to turn on at less than 196, so a 160 can't do much except when you're moving. A 180 is just right for that temp.

[68Formula]

A few years ago I saw an article with a graph of engine wear rate vs. engine operating temp. As it dropped from 180 to 160° there was a significant difference. I have it stuck in my head that 170° is as low as I would ever go in terms of trading off power vs. durability.

[WS6]

Steve, do you have this thermo in your hand? Have you looked to see if it has a temp rating stamped on the backside down in the hole?

[Steve1968LS2]

Steve, do you have this thermo in your hand? Have you looked to see if it has a temp rating stamped on the backside down in the hole?

Unfortunatly it's installed in the car.

I just noticed that it idles at a higher temp now. Before I had a SBC t-stat (180-degree) in the elec pump and it idled at 180-190

Now with the mech pump and this t-stat the idle is 210 or so. Part might be that the mech pump isn't as good at idle (ie, slower)

[Steve1968LS2]

A few years ago I saw an article with a graph of engine wear rate vs. engine operating temp. As it dropped from 180 to 160° there was a significant difference. I have it stuck in my head that 170° is as low as I would ever go in terms of trading off power vs. durability.

Yea, and LS engines typically make more power when they are warmer.

That's why sucessive dyno pulls typically go up rather than down like a Gen 1 engine.

[Vegas69]

Grab your laser thermometer and shoot the t stat housing and you'll know exactly what temp the stat opens at.

[Twentyover]

Can I ask what the rationale is for not being satisfied with a 210 degree idle temp? With a pressurized cooling system and coolant,your boiling temp should be about 250 degrees.

[WS6]

Steve, stock LS2 thermos are either 83 or 86*C which translates to 190*F or close enough. You're running right where you should be with a stock water pump and thermo though. Putting in a 180* won't help much in this case. I'm assuming you have the fans turning on in the 180-190*F range. Why the switch back to mechanical from electric?