What Temperature Thermostat

[Tiggie]

Just what the title says, what temperature themostat should I get?

Keep in mind I don't have EFI or any of that stuff requiring me to run a hot one.

I've always ran 180's, but I was thinking of a 160 since I witnessed a '71 Cougar with a 429 pick up 15 horsepower throughout the rpm range by a simple 190 to 160 thermostat change.

Whadda think? 160 or 180?

[gadget73]

warmer is more efficient. Run a 180, it reduces engine wear and keeps the oil thinner.

[turbo2256b]

You might just change to a 160 and loose 15 hp. Lot of it depends on carb jetting, timing inital and total, core shift and casting flash in the water passages, water pump efficenty, delta across the inlet and outlet of the radiator. List could go on. 180* is the best for cylinder wear. I changed to a 160 on my 84 Stang and it ran hotter beecause the radiator wasnt big enough to cool the engine with the thermostat opening that soon.

[Tiggie]

I'm not really concerned about wear on this engine, it is coming out in the spring. I just want some heat for now, my thermostat is stuck open!

I'll probably just go with the 180 unless anyone has a decent reason to go with the 160.

I know I wouldn't pick up 15 horsepower anyway like that Cougar, that'd be an 11% increase over stock!

[Mercmarquis]

I running a 180* in my car now, and with the cool weather my car never sees over 160* now. I'm gonna switch to a 195 soon cause I dont like the car running that cold.

[gadget73]

My car also ran about 170 most of the time in the winter with a 180 tstat. Runs 190-195 with a 195 in there. Heat is much better too.

[gabegt90]

I have a stant 195 temp in the winter my car normaly runs 197-205 in the winter

[86GmLsCoupe]

I'm going to replace the thermostat on my 86 GM and just wanted to make sure I get the correct replacement. Motorcraft and Rockauto's catalog both list my car as having a 190 F t-stat but I always thought it had a 195 F one. I know the difference is small but is the 190 F what was originally put in? Thanks

[gadget73]

190. 192, 195 are all values I've seen listed as original. Somewhere in that neighborhood is fine.

[Rob Roy]

I have read articles on engine temperature vs. wear, the general consensus was that a 180 degree coolant temperature was the best compromise between performance and engine wear. Not only is wear accelerated with too low of a coolant temperature, fuel dilution of the engine oil can be a problem as well. I have seen thermostats stick open on large diesel engines and the used-oil-analysis that followed: iron, copper, and lead levels were all elevated and plenty of fuel in the oil. Of course this is an extreme example, but it gives you an idea of what happens when an engine is run at too low a temperature.

In summary, I think there would be little to no gain by using a 160 or 180 degree thermostat on a stock engine with a design temperature of 192-195F. You *might* be able to run a little more timing, but only slightly more. Any horsepower gains from the reduced intake manifold temperature would be small, and hardly something you would feel from the driver's seat. I briefly ran a 180 degree thermostat in my 1997 Crown Vic in an effort to eliminate pinging, and the only difference I observed was slightly lower fuel economy; based on that I concluded that the engine's sensitivity to pre-ignition was the same with either thermostat.

In the end different people will all tell you to do something different, my recommendation is that a stock t-stat is a good choice for a stock car.

[gadget73]

I've seen those too, and the ones I saw indicated that a 190 was optimal for both wear and performance. I wonder if it depends on the specific engine, or if some of these numbers are just pulled out of the air.

[mrltd]

if you want heat, use a hot thermostat. Pretty simple logic. I run a friggin 195 in the wagon and it still never really gets warm unless I block off half the radiator with cardboard.

[86GmLsCoupe]

Thanks for quick replies everyone, very useful info. I'm going to go with the 190 F Motorcraft since I prefer oem parts, especially when only so many are available, and it only costs like $6-7. I'm hoping mine hasn't been hanging open for to long. My heat just started that cutting out on the highway stuff but since the blower resistor went there's not really a good way to test it. That said the heat's always been very good in the car. Also, my fuel economy could be better and the car is in good shape such as recent Motorcraft coppers, plugs, cap, rotor, air filter, a good 20-22Hg at idle, ect. Perhaps after this I'll toss in new air charge temp and coolant temp sensors since they're old, the car runs a little off, and less than ideal mpg's.