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170/160 degree thermostat?


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On ‎8‎/‎5‎/‎2018 at 7:31 PM, cdh027 said:

Any benefit to a cooler thermostat on a 2018 6.0?

Any benefit to running a hotter one? GM thought so after decades of installing 180 F in nearly everything they make they started to creep up. 192 F, 195 F and now 207 F. To what end? Emissions. NOx emissions are lower under WOT when the motor runs hotter. Part of the test cycle. (Funny Honda passes these test with 180 F stats qualifying for ULEV standards and their motors last seemingly forever.) 

 

Two questions. 1.) What effect does heat have on any mechanical or electrical device? 2.) How cold would be too cold?

 

If you can answer the first then you already know the benefit and can proceed to question two. If you can't then it might be wise to leave it alone until you can.  

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The L96 still uses the same 186 degree thermostat they have run in LS's forever.  The direct injected stuff in the 1/2 tons runs a hotter one but that is no concern.  A cooler t stat might help with heat soak and underhood temps to a degree but is it enough to warrant swapping it? By design the 186 degree unit results in a 195 or so engine temperature.  I live in a cold climate and I like heat so I leave it stock in my daily stuff.  Even my turbo car has the stock thermostat lol.  Its intake temperature starts killing power but that has little to do with the coolant temperature.

Edited by SierraHD17
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  • 2 weeks later...

http://www.enginebuildermag.com/2017/06/tempering-horsepower-heat-keeping-cool-heat-handling-accessories/

EFFECTS OF CHANGING THE
OPERATING TEMPERATURE

Installing a lower temperature thermostat can also lower the average operating temperature of the engine, but it won’t necessarily increase cooling. It only means the thermostat opens at a lower temperature and the coolant starts to circulate between the engine and radiator at 140 or 160 degrees instead of 180 to 195 degrees F.

One of the advantages of lower operating temperature is that it reduces the risk of detonation, which means you can get by with a little less octane in the fuel and/or take advantage of a slightly higher compression ratio for more power.

A cooler engine also allows a denser air/fuel mixture into the cylinders for more power. But if the temperature is too low or the engine is run without a thermostat, it can be very “cold blooded” and idle poorly, hesitate and stumble until it warms up. Too low of an operating temperature can also increase clearances between the pistons, rings and cylinders, increasing blowby and washing oil off the cylinder walls.

On late model street vehicles with computerized engine controls, the coolant operating temperature affects all kinds of things from when the fuel feedback system kicks in to fuel enrichment, ignition timing and emission functions. Changing the operating temperature with a lower-rated thermostat can really screw things up unless the PCM is reprogrammed for a lower-operating temperature. ( end quote)

Maybe...maybe not. That should read when it leans the fuel table not "fuel enrichment". Cooler motor maps run richer not leaner. It is normally a trigger point and not a progressive table. More often than not this slightly richer mixture results in an improvement in fuel efficiency and slight reduction in emissions...maybe. "really screw things up" is kind of a play on ignorance of the exact mapping involved. A scare tactic.  If this were a hard and fast situation then even a oil cooler would have a drastic effect both economy and emissions. It does not. 

I would never run a 160 F in a street motor in consideration of moisture in the lubrication system. That white foam that collects in the breather of cold motors. That said 207 F is stupid beyond all reason in a motor that calls for 87 octane and has a mechanical compression ratio of 11:1. Even with KR. 

I have actually used a cold thermostat or enhance oil cooling to lower system temperatures enough to richen motors enough to not only gain some power but enhance fuel economy as well.

Quoting my father: "Lean motors are neither powerful nor economical. They tend not to live long lives either". 

I've been running a 170 or 180 F stat for nearly two years in my Ecotec3. It is not "really screwed up", it is a great deal more economical and runs less KR than it did previous.  

Tell you what Ecotec3 sort of heat will do. (207F coolant 225-230 F oil). Shorten component life for you and enhance EPA mileage and emissions numbers for GM...on paper.

Two years of fuel efficiency. Second season is with the 180 F stat. First the factory 207 F stat.  (red sections) 

 

 

Pepper by Year..png

Edited by txab
added link to quoted info
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