The intent of running a lower temp T-stat serves a couple of purposes: one is to prevent overheating in certain climates / conditions and, to gain a minute amount of HP in other cases.

By running the engine cooler, this results in cooler air at both the intake and cylinder level thus producing more power. Colder air, in theory as well as well as in real world testing, produces more HP vs. hotter air / hotter cyl temps. Some go as far as dropping the incoming air with a cooler, chiller or other means. But, the intent is that, the cooler the air, an increase in performance can be noted. However, on a stock vehicle or even a tuned vehicle, the difference is negligible for the most part. Now, in combination with other mods, the gain in HP will start to add up and, overall, a noticeable difference in how the vehicle feels. Such is not the case when running a lower temp T-stat stand-alone. I've personally been running 180 T-stat since moving to So Cal and never noted an increase in performance on that alone. It simply ran cooler which, is exactly the end result I was going for.

So, Hughes, among others, squeak out a little more power with additional little mods. That's all they are doing- trying to gain a little more here and there.

CM

 

Thanks man thats exactly what I wanted to know. I had the 180 degree in during last winter and the truck got way worse mpgs. Hammer said that you might see a little increase in power with a 180 , but I'd rather have the extra mileage.

 

Before I'd take Hughes' word for anything, I'd ask the produce manager at the local grocery store and get confirmation from the chick who takes my order at the taco stand.

I like the 180 degree thermostat because it's nicer to the automatic transmission, not because it might magically make my truck into a rocket sled.

 

That was quite possibly due to "winter fuel" that sports a heavier dose of corn. Er, uh, ethanol.

 

True, plus i'm having to push 33's on 3.55 gears with the a/c on which doesn't help matters either. My truck works alot to get up steep hills

 

My a/c also kicks out when climbing a big hill in od. Is that normal or a vaccum leak?

 

Do the vents just switch to defrost? Or, does the compressor actually quit running?

 

Uh, well: Yes. It's normal, but it will happen sooner if you have a leak or a failed vacuum check valve. It'll happen sooner if you've got old, dry, porous vacuum lines, which you almost certainly do have.

Don't climb big hills in overdrive. The money you save will be your own!

 

Vacuum is controlling vac-switches for where the air flows. It has no affect on the compressor running or not. Now, there is a function at the PCM level- (memory fails to recall) that monitors the AC.

I'd have to look that one up as, I can't remember how it functions.

CM

 

180* stat HURTS MPGs. Because the engine is cooler, it shows a cooler reading, so there will be more fuel added to the mix since the intake temp will be lower.

I80* makes you spray more fuel.

As far as switching to your defroster vents when going up a hill, yeah, that is ussually linked to the plenum and that T valve vac line that is on the passenger side rear of your engine. just follow the thin vac lines from your firewall down and you will get to the T valve vac line.