Patrick McDaniel

I have seen several places people replacing their thermostat with 160 degree thermostats.

Is this a good idea?

allanlaw

Considering how much cooler than a C5 it seems to run stock, I'm not sure I see the point. However, I don't think it can do any harm.

forhamilton

I have a 160 degree thermostat. Seems to run cooler on the street. On the track is doesn't matter.

Down side is it takes longer to warm up.

More important may be to have fans come on earlier.

What are your intentions with the car?

louieT

Would it matter as far as hurting the car..? I would bet it is better to keep it cooler, right..?

Exterminator

Something may be wrong, the stat should only open when the coolant in your block reaches 160 as opposed to whatever stock is (I'm not sure in the Z06 in my Cobra it was 195). 160 should be "warmed-up"

Maybe your stat is stuck in the open position and this is why your car seems to take longer to warm up.

I agree that it is more important to have the fans come on earlier.

Patrick McDaniel

Mostly street use with occasional track time. I was just wondering how important the 160 stat I was reading about was.

forhamilton

It is important to watch oil temps and not just coolant temps when you start asking an engine to perform.

Stat is not stuck. Oil just takes longer to come up to 150 or so when the engine is running cooler.

The fans coming on earlier is essential in high temps.

Nitrodamus

The theory was that cooler air entering the engine is denser and containing more oxygen to mix with fuel. For old pre-engine computer Corvettes like my 63’ and 66’ I run 160 degree thermostats.

My C6 Z06 will keep the original thermostat the engine and its computer was designed to operate with. Unless an engine tuner resets the parameters preset by the factory, the ECM will assume the engine isn’t at operating temperature at 160 degrees and adjust the fuel mixture for a cold engine.

Foosh

A stat doesn't do a single thing to "baseline" engine operating temp once it opens. It simply opens at a specified temp, and then stays open until the fluids cool below that point. Changing a 190 stat. to a 160 just alters when the fluids start flowing through the radiator. Once they start flowing the operating temp of the engine is the same, regardless of the thermostat's rating.

Warm up to the "factory specified" temp. would take longer with a 160 degree stat, and because of the physics of heat transfer, the oil temp would also lag behind a bit.........not much. So, perhaps, at best, you gain maybe 5 minutes of cooler temps. However, cooler is not always better if you're below 190 in this engine (in terms of engine component wear).

Obviously, changing the temps at which the fans come on would have a greater overall effect than changing the stat. However, even this effect is small and of limited time-duration if you're running hard.

If you're a "Ranger" and want to keep the engine at 190 or so for max HP, prior to a 1/4 mile run, you might gain some benefit.

louieT

Now thats a explaination..

Answered my questions...

robvuk

The engine will reach 150 just as quickly as it does with a 190 thermostat.

I might add to Foosh's excellent explanation by putting it another way. If you tune the computer for the 160 temps, it will make more power. The downside is that it will rarely run at that temp very long during summer months. The engine will have a wider range of operating temps above 160 and will be less effective overall.

This is why 160 might be fine for the dragstrip. You get to cool down between runs and if you get to the line and launch before it runs up above 160, there will be some advantage. On the street or track, there would be no benefit.

Everett Ogilvie

Many don't understand what the thermostat regulates. Many think it "helps" control or lower the upper end temps. It has NOTHING to do with upper end temps. It controls the low end temps - meaning, it is supposed to set the lowest operating temp your engine can ever achieve once the engine has warmed up past the thermostat point. Here is the easiest way to think of it;

The temperature operating boundaries of any engine can be thought of as;
Upper engine temps - controlled by cooling system capacity and design, and type of vehicle use (includes the fan set points, ambient temps, and operating modes such as idling in traffic vs highway running, running on a track under severe high loads, etc.).
Lower engine temps - in extremely cold weather, going down the highway you may occasionally see the cooling system try to drive down the engine temp - it will only go as low as the thermostat set point, then the stat might close briefly, engine temp will start to climb, stat will open, etc. The stat controls low end temps.

What some get confused about is the fact that low temp stats may sometimes "delay" the engine from reaching final, steady state full operating temp. And this is only under some conditions, and the design and margin built into the cooling system.

160 is too low for modern engines, especially if it delays reaching full operating temp appreciably. Combustion and engine efficiency get better with temperature. Cold running engines create deposits and have low efficiency (remember Carnot efficiency from basic Thermo?). On really cold days a low temp stat can appreciably delay reaching optimal operating temp, and in extreme cases can prevent it altogether. Because the stat has no impact whatsover on upper temp, you need to choose it based on desired minimum operating temp, which is why 160 is too low.

For the Z06, fan setpoints is where it's at if you want to keep temp around 200, but the cooling system capacity will even override fan setpoints under extreme operating and ambient conditions.

Bill Dearborn

Great Post.

Bill

Patrick McDaniel

So why does Lingenfelter install a 160 degree stat in their mod Z06?

Do they know something we don't?

http://www.lingenfelter.com/pacc6_ZO6camintake.htm

robvuk

Tuned for 160 = more HP on the dyno not the street.

hapnermw

Before someone makes the mistake of putting a 160 degree thermostat in their car it is worth reading the quote below written by John Hinkley in an article he wrote for Corvette Enthusiast. The thermostat is for controlling warm up and minimum operating temperature. The Z06 OEM thermostat was set to balance many operating parameters including air quality, engine wear, combustion efficiency, etc. Perhaps someone has done the research to prove that LS7's run more efficiently with a 160 stat but I've yet to see one fact that supports this.

I had the opportunity to talk with Mr Dewitt, a forum vendor and expert on Corvette cooling about this. He had some involvement with the development of the Z06 cooling system. The radiator on the Z06 is at the edge of its cooling capability for the 'hotter' end of track use. His replacement radiators for the Z06 have significantly higher cooling capacity and hold an extra gallon of coolant (the extra 8lbs is one of the reasons they weren't used by GM). They are cheap track insurance for your LS7.

'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 yourengine 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.'

http://www.dewitts.com/download/cooling.pdf

Futfixr

The engine more than likely through all the testing works optimal with the 190deg stat.

Patrick McDaniel

I guess we need to just drive on the dyno and not on the street!

Everett Ogilvie

I know John well, and agree with all he says, which by the way is pretty much what I said above. I am not quite sure why Lingenfelter is putting in a 160 stat - because at most it will only delay the engine hitting full temp. Consider this - you have the 160 stat in, and you are in downtown Phoenix and the ambient temp is 120... You are idling in traffic, and your coolant temp creeps up to 220 (which mine did recently, although not in Phoenix). Do you think your thermostat is even "in the circuit" at this point? It is not - it is wide open and has no impact on the max temp your engine will hit. Once you get out of traffic and take her up to speed on the freeway, she will creep down to maybe 200 or 205, at which point the stat is still not having any impact. The thermostat controls the minimum operating temperature - the cooling system design and capacity control the upper end.

Now take the other extreme - you are driving at 70mph on the freeway and the ambient temp is near zero. You should be extremely happy that you have a 193 degree thermostat! Without it your heater would not work worth a flip!

Adrenaline Junky

After reading all these posts it seems to me that my 160* Thermostat is irrelevant. I think the most important aspect is switching the fan motor to be at 90% earlier and hooking your fan ( stock or EWP ) up to a manual switch so it can be on for as long as you want after the engine is turned off.