Which Thermostat? 180 or 190 degree?

[Mtn8er]

I'm going to be putting in a new thermostat in my Mountaineer 5.0L but I'm not sure on which one to put in. I have a JET high flow 180 degree thermostat and a stock OEM Motorcraft 190 degree thermostat (which is whats in it now). I also have an Xcal II and a custom torque 92 octane tune from Doug at BamaChips. Does it matter on which thermostat I go with? If anyone knows please let me know.

 

[02whiteXLT]

put in a 180 degree thermostat, a 190 is just too hot, i have 180 degree thermostats in 2 302's in my mustangs and it runs nice and cool

 

[aldive]

put in a 180 degree thermostat, a 190 is just too hot, i have 180 degree thermostats in 2 302's in my mustangs and it runs nice and cool

Stick with the stock 190-195 F thermostat. Your engine was designed for it and will run better and get better gas mileage.

 

[02whiteXLT]

its your choice but id rather use a 180 degree you engine will run cooler, and the mileage wont drop never did in all the 302's i put one in

 

[wyochimneysweep]

use the 190 unless you are driving across the desert

 

[btexpress]

its your choice but id rather use a 180 degree you engine will run cooler, and the mileage wont drop never did in all the 302's i put one in

The PCM in a 5.0 Mountaineer is programmed for optimal operation at around 195. Using anything colder will just screw up the emissions and the PCM. Just drove my Ranger all over the Rockies, stock as factory, temp gauge stayed right where it should the whole trip, thru 95 degree heat and 38 degree nights.

I do use a 180 in my 48 Ford 302, but it has no computer and no emission controls.

 

[Turdle]

I personally would use the stock higher temp thermostat. You'll see a bit more power and efficiency with oil temp around 185-195

 

[lbrlh8r]

depends on what ya want. You'll get less emissions and better MPG (slightLY) out of the factory one. The 180 will tell the computer to dump more fuel into the engine... so you'll get more power out of the 180. I run the 180, although you can tell a big difference inside the X when winter hits up here

 

[aldive]

so you'll get more power out of the 180. I run the 180,

Not necessarily.

 

[Hokie]

The 180 will tell the computer to dump more fuel into the engine... so you'll get more power out of the 180.

If this was a diesel engine, then your assumption would be correct (to a degree). But more fuel does not mean more power on a gasoline engine.

 

[lbrlh8r]

yes, it does. Go check out the hotrods sometimes. JET makes a 160 t-stat for the LT and LS series engines for a reason. The factory programs em to run a little on the lean side for emissions. Enrich the fuel a bit and you'll see more power. Of course, other mods will showcase this (intake/exhaust) but it happens none the less. If not, every camaro/corvette owner wouldn't bother changing em.

 

[Hokie]

A colder thermostat allows you to run a more aggressive spark advance, without the risk of pinging.

 

[02whiteXLT]

the 180 will not make the engine run rich, any temp lower that 170 or 175 the computer is still in warm up mode durring this it wil make the mixture a lil richer to help warm up, i would rather have my cars run cooler than hotter, and it does prevent pinging

also to add i put a 180 degree thermostat in a explorer i HAD and it ran so much better, cooler, my mileage went up 1 to 1.5mpg and my air to fuel ratio stayed the same

 

[wyochimneysweep]

oh by the way a ran 180 in my 302 97 and it never warmed up and set a cold for insuff coolant temp for closed loop it ran right at 178 to 182 degrees and even on the hot days with a electric fan set at 205 degrees it would never turn off the light so running in open loop really affected my mileage badly. went back to the stock t-stat i pulled out

 

[gijoecam]

Oh, lord, the old thermostat temperature question again...

Changing the thermostat alone on a STOCK engine will make the engine run a bit cooler, yes. It will not, however, give you more horsepower as the engine operating temperature is but one operating parameter monitored by the PCM when the engine is running. Unless you modify the programming, there are no significant gains to be had by running cooler.

And Al is correct: A cooler-running engine alone does not in and of itself guarantee more horsepower. There are a LOT of other variables to take into consideration.

-Joe