I currently am running a 180 in my 400 shp, it runs consistently at that temp. It seems to run better in the 140 degree range. I only know this from getting on it around that temp. I've heard that some race only type engines don't want over that, but I don't know this to be fact. I've also heard that 180 or 190 is optimum for street engines, but if it seems to pull harder in the 140 range would it hurt to run it in the 140 range. I'm ready to hear all sides of this, including what you run.Tthanks in advance.

 

Stock '81 with DeWitt radiator-195* thermostat...good luck!

 

Stock '82 180* I have noticed a 15* lower temperature difference, which is great driving in Florida summers. HVAC runs cooler also with reduced heat underhood. Temp guage never hits the 200 mark

 

Stick with the 180 for the street.

 

Always run the Milodon 160 and never had a failure
usually runs 180 around town 170-180 hwy just right

Lots of dyno pulls are made at lower temps like that to sell a hp#
Might shorten the eng life a bit but who cares...how many modded motors really ever get driven let alone hold together to 100k anyway

If you live in a cold climate the 180 may be a better choice

 

If you are asking if you can run a 140* thermostat to get your engine to run at 140*, then the answer is...probably not. If you install a 140* thermostat, all that means is that the thermostat will open at 140*. It doesn't necessarily mean your coolant temp won't go any higher than that. I suppose if you had a big enough radiator it would, but 'vettes have pretty marginal cooling systems from the factory. Plus, you want the engine to run hot enough to quickly boil off any moisture in the oil, which is one of the reasons thermostats were invented, to let your engine's coolant come up to operating temp quickly. If your engine pulls harder at 140* coolant temp, you may be looking at a tuning issue. Also, why are you beating on it before it's up to operating temp?

Edit: Look at cuisinartvette, he runs a 160* thermostat, and his engine runs at about 170-180*. If he switched to a 140* thermostat, his operating temps probably would not change one bit, it would just take a little longer to get up to his 170-180* operating temp. Once the thermostat reaches it target temp and opens, it no longer has any effect on anything. BTW, I run a 180* thermostat in my '80 'vette, and the coolant temp rarely goes above 180* at operating temp. (aftermarket aluminum radiator and engine driven clutch fan)

Scott

 

there is absolutely nothing wrong with running 200*-205*

 

Stock L82 in my 73 with a 180 degree thermostat. Runs 180 with it going slightly above when running at 65MPH for an extended time. I'm happy with it.

Fran

 

I read recently that approximately 95% of engine wear comes from start up to operating temperature. After that wear is almost nonexistant. So if wear is a concern in any way then you will create more wear on the engine by making it take longer to get up to temp.
If in a cold climate running a 140* t-stat your engine may not rise above 140*. 180* to 200* seems to be optimum for wear. 160* or lower for power.
I run a 180* t-stat myself. It does rise up to 200* or so on a hot day with the ac running while in traffic.
The max temp your engine will get to depends on many factors. The lowest temp will be determined by your t- stat.

 

Or even higher if all components are up to it.

Flame suit on.

 

Pretty much as long as the coolant doesn't boil, you won't be causing any engine damage. Might see some long term damage from higher under hood temps, like plug wires and such, but that's about it. When I was in the military, it was rare to see a HMMV running at less than 220-230*, it always made me a little nervous, but the mechanics all said it was normal. And, since Mike has his flame suit on, I'm going to take this opportunity to say that he is a big, fat jerk. (Just kidding, Mike!)

Scott

 

Ok so if I weren't imagining a performance difference at 140, why would it be? Intake air temps maybe?

 

You may not be able to detect the difference by "seat of the pants" or you might. Kind of depends on what temp you are comparing it to.
You are correct. the intake charge would be cooler and denser allowing for more power to be made.

I would not agree with this statement in all circumstances. 20* to 30* degrees may be the difference between detonation and not.
A higher water temp can cause problems in an air intake that has the water circulating around it if tuned on the edge of deto for performance or fuel economy. Then to counteract the additional 30* of water temp, timing may have to be pulled and/or mixture may need to be enrichened to stave off detonation problems.

 

Assuming you're not on the ragged edge of detonation and you can keep your fuel and intake cool, the hotter the engine runs the better, as long as the materials (bearings, etc.) and oil are up to it. The bigger the difference between your cylinder head temperature and the coolant temperature, the more energy is lost to the coolant and radiator. That energy is better used in the combustion chamber to make more power.

Acids, combustion by-products and moisture end up in the oil, as Scotty stated. If the oil isn't heated to about 180 degrees, those contaminants don't separate from the oil and get drawn-off and burned via the PCV system. You don't want to run a T-Sat lower than 180 for this reason.

Regarding the wear occurring between cold start and operating temperature, the operating temperature must be reasonable. You can't just arbitrarily say you're going to make your operating temperature 120 degrees and think no wear is going to occur after 120 degrees. The operating temperature has to do with all the engine components heating up and expanding to their running size and clearances closing up and running within the design spec's that the engine designer or builder determined. And there's the oil again, cold oil doesn't flow as well as when it is warm. I'm sure this is pretty elementary compared to what's really going on.

 

Decreasing coolant temps has almost no effect on intake air temps. Certainly not seat of the pants levels.

 

I get that, but if the engine is running at a cooler temp, wouldn't the engine compartment be cooler causing a cooler IAT? But like you said, the gain with temps that hot probably wouldn't be noticeable. what would make a difference at a 40 degree change in engine temps?

 

110%. The 85-96 Corvettes cooling fans do not even come on until 226-228 degrees Fahrenheit.

Run either a 180 or 195 degree thermostat. It is all about getting the system to cycle as designed.

DUB

 

I run a 180 with a street built 358 its around 350 horse and it runs 185-195

 

Well I know its off topic, but what trucks were you running? Our 1151's (Fully armored, 10,000 lbs and a massive A/C system) in Kuwait during summer (120 degrees) would run 230 all day long with no ill effects.

I do get a little spooked when my big block gets to 220, but Im told thats fine also......I run 190 around town, but in HOT weather the car will hit 210-220 and stay there until I shut it off for at least an hour.

 

My 2012 sierra runs 210 constantly, but it has knock sensors and all the modern gadgets. The gauge on my 76 doesn't hit the red until 240. It runs 180 constantly, so no fear of over heating. Why does it seem to pull harder at 140?