Not So Fast

At the risk of repetitiveness I read this and thought, wow, good explanation. So maybe you would like to read and learn as I did
NSF


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Quote:

THERMOSTAT: Probably the most misunderstood component in the cooling system, the thermostat has absolutely nothing to do with controlling maximum engine operating temperature. Period. What does it do? At cold start, it blocks the flow of coolant out of the engine until the trapped coolant reaches the thermostat’s rated temperature, at which point it opens and permits coolant to begin circulating. This aids rapid warm up, which reduces cylinder bore and piston-ring wear by bringing the engine up to operating temperature relatively quickly. Once it’s open, it modulates the flow of coolant through its calibrated restriction so coolant temperature never drops below its rated opening point, assuming the cooling system is efficient enough to cool the engine down to that level. In most cars, it’s essentially wide open all the time, and only the heat transfer efficiency of the radiator and the airflow through the radiator determine the engine’s maximum operating temperature.

If you have a 180º thermostat and your engine operates at 220º, changing to a 160º thermostat won’t change your operating temperature one bit – you need more radiator, more airflow, or both, to reduce operating temperature.

If you have an extremely efficient cooling system with more heat-rejection capability than your engine needs (runs at 180º with a 180º thermostat), changing to a 160º thermostat may result in reducing your operating temperature to 160º, but this is rare except in cold weather. Furthermore, 160º is too cold; OEM testing has proven that the rate of cylinder bore and piston-ring wear at 160º is double the wear rate at 180º, and a coolant temperature of 160º won’t let the oil in the pan get hot enough to boil off condensed moisture and blow-by contaminants, which then remain in suspension and accelerate the formation of acidic sludge. 160º thermostats were specified in the 1930s for the old alcohol-based antifreezes, which would boil off and evaporate at 185º; there’s no other reason for them.

“Balanced-Flow” thermostats like Robertshaw makes (also sold by Mr.Gasket with their name on them) are calibrated much more accurately than conventional parts-store thermostats, and if they fail, they do so in the open position. Conventional thermostats fail closed, which can cause a lot of engine damage in a big hurry if you don’t spot the sudden temperature rise.
http://www.dewitts.com/download/cooling.pdf

Given the information above, why do so many people buy and install 160* thermostats for otherwise stock Corvettes?

Totally get it if substantial mods like S/C and/or H/C packages are being done along with other upgrades to the cooling system for the track.

I'm talking doing this for a Corvette that will NEVER see the track nor ever be modded other than maybe a tune

Rich Farr

Although I have a 160 degree thermostat. I believe the main improvement you can make is to have the fans come on sooner. My car consistently runs in the high 180's. The car just runs so much better on a hot day or in stop and go traffic. If the car was winter driven the 160 degree thermostat could be a problem.

Gary '09 C6

...but, can't the radiator fan be programmed to come on sooner (if desired) without changing the thermostat ?

enventr

Using the A/C will activate the fans

Gary '09 C6

yes, I am aware of that (thx).

Not So Fast

But then haven't we seen where the wiring has not held up because it wasn't designed to run on and on??
More to the point, I have read so many posts on this that I thought this was a through explanation as to what and how the thermostat operated FYI.
NSF

Gary '09 C6

I do agree NSF...it is an excellent post.

It is a much discussed subject here on the CF that is also at times confusing (to me).

sonic1519

has anyone ever noticed, i'm sure you have. when the outside temp is below 50 degree's or so it seems like your car has gained an extra 20 HP.

They just seem like they pull or run a lot better

Not So Fast

I live in Lake Havasu, questioned answered ??
NSF

SladeX

On my LS3, I have heads/cam/full exhaust and a mill on the heads. I think we figured out 11.4 compression. At 190+ on temps, I get detonation in the mid-upper rpm. running a 160 gives me an avg 173f temp cruising even in summer heat. Fans come on 183 and off at 170.

If you are stock, there's not much benefit. A tune is necessary to take advantage of cooler combustion temperatures and a bit more timing. Unless you have your own tuning software, at stock it's pretty costly for a few extra hp. LS engines are really efficient at higher tempstoo for emissions. The balance of the 200f, power and emissions is the key for why it runs that hot stock. I can technically go 94 octane and go back to a stock timing and temp but 91 octane where I live has no ethanol which at higher power levels is the a good chunk of mileage I am giving up for cruising use.

AORoads

I know it says "quote" and that a DeWitt radiator thread is quoted, but is that where this explanation came from, Bobby? It'd be good to see the source for those who care (I do think I read this one recently and that it was from DeWitt).

I also heard as Gary mentions that the fans can be programmed via a tune to come on early, and stay on, but that some form of burning out could happen, too. I don't know/recall if it then means an upgraded fan(s) is needed, or that it is used safely only in combination with a lower-temp thermostat which will then allow the fans to turn at lower speeds much of the time.

Good post tho---and maybe it should be referenced each time there's a "should I change my thermo or "stat?" thread.

not08crmanymore

I read years ago,don't remember where or by who but probably from here, that a 160 stat is not recomended if you live in a cold climate because it causes sludge. Then I heard that part about the engine not getting hot enough to burn off the contaminants in the oil..that was all I needed to stay away from that snake oil.

RocketDawg

So do you lose 50 hp when the temp is 120?

Dave S

At lower ambient temp, air is more 'dense' & thus holds more O2, which engines like. Think of Pikes Peak....air is more dense at the base than the summit....thus more HP at the base than the summit.

Boomer111

Running the 4:10 gears I see cooler temps due to the water pump seeing more revs. With the 180* stat I see 189-196 depending on rpm, the sweet spot so it seems.

With the 160* it was just too cool showing sub 170* mostly.

Dcasole

What degree is the stock LS3 thermostat?

Dave

Not So Fast

I assume the info was from Dewitt, Bill. Just seemed like a very logical explanation to me. I know there are variance's and exceptions to the rule but this explains it so that I could understand
Bobby
Bobby

5knives

187*

5knives

With the frequency at which Corvette owners change their oil, do you really think sludge is an issue?

simplegto

The moderators should lock threads that are posted for no other reason but to start arguments.