operating temperature
 

I need to know what the "normal" operating temperature should be for the 850 turbo. (96 wagon to be exact)

I've found four different thermostats for the car, ranging from 160'F to 192'F. I'm running tests with three of the four to see which temp zone is right for this turbo model.

if it helps, the car lives in texas, fans work, timing belt/water pump are new, new headgasket, no coolant loss.

Thermostat starts to open around 186' and the car will run as warm as 212'. Most of the time around 192'. I run a ScanGauge.com in my car most of the time with the temp displayed. After I drive, I often check info and find that the temp got as high as 209 to 212.

This is the stock thermostat for the turbo 850. It is a 187 thermostat.

Stock Turbo 850 Thermostat

The thermostat from Ipd let's the car get as high as 225 and failed after only a few hours. (kinda odd, but it may have been damaged in shipping)

The 187' from a local parts store let's the car get up to 216 and the "mystery" thermostat from a local Volvo shop gets up to 222'F.

The car does not currently have the air guide that comes on the car, previous owners must have lost it. How much of a difference will it make? I know from experience from my s60, that when it's not installed the fuel mileage suffers by about 2%. I know it's not much, but I want to milk every mile out of each gallon.

The air dam does help with cooling the engine and just keeping the engine compartment cooler. If you don't have one, I would consider at least getting the stock plastic one.

Does your temp gauge go above the midway point ( 3 oclock)?

None of mine ever does. It stays right in the middle even with the 25' temp sway.