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Cooler thermostat

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Old 02-24-2011, 10:53 AM
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Default Cooler thermostat

I was talking to one of the mechanics in our garage yesterday and he suggested putting a cooler stat in my MC, (190 degree or so) I used to run 165 stats in my older non-computer brain cars but never messed with these newer cars,.. Do any of you run a cooler stat??
Old 02-24-2011, 11:02 AM
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I have been wondering the same thing.
Old 02-24-2011, 11:22 AM
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i have a 160 in mine. iirc the front manifold has to come off to change it.
Old 02-24-2011, 01:07 PM
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I was going to run one, but as you mentioned, these cars already have a 185-190 degree t-stat. In talking to several mechanics, I've been told there's no benefit to going to a 160, and you might even lose some fuel economy and have trouble with emissions.

Also, if you did go ahead and do this, you'd need to get a tune that lowers the fan turn-on temp. Otherwise, it's a complete waste of time.

Edit: The above info applies to near-stock or bolt-on car. Obviously, 2005gxp's car is a bit more modified, and I'm sure he benefits from a 160 t-stat due to his turbo and stuff.
Old 02-24-2011, 01:34 PM
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i also passed emissions test with the 160 installed. passed very well compared to ALOT of the vehicles i test lol
Old 02-24-2011, 01:49 PM
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Hotter engines produce power more efficiently. You run afoul of this when your hot engine is causing predetonation or heating the intake air/ combustion chamber and thus lowering the air/fuel density mixture. The happy zone is the highest temp you can handle before the above issues start limiting you. If that zone requires you to use a lower thermostat then that's what you do.

Since it's highly unlikely you'll find anyone who has done a dyno pull or track run with the only change being the thermostat, it's all going to be circumstantial anecdotes as to what's better for stock or better with a cam change or tune.

You go with the highest temp before predetonation is a very good rule though. Engines are little more than heat pumps and any heat lost into the block is heat not doing any work. Cooler thermostats increase this heat loss, but the idea being it might allow for denser air/fuel mixtures without detonation.
Old 02-24-2011, 03:53 PM
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The fans won't turn on below 192 or so after programing (over 200 stock), so running a cooler thermostat is not going to change the engine's operating temps in warm weather. It will make the engine take a while longer to come up to full operating temperature in the winter.

Personally, I've never seen my engine temps dip back under 187 and cause the thermostat to close, and I'm a bit farther North than you are. If that is also the case with your engine, then you would see no benefit from switching to a 160.
Old 02-24-2011, 08:48 PM
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Ok, thanks for the input, us Bowtie guys don't have the nice gauges that the GP's do... all I know is that my temp gauge goes halfway....No idea on the temp.
Old 02-24-2011, 09:48 PM
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Originally Posted by safemode
Hotter engines produce power more efficiently. You run afoul of this when your hot engine is causing predetonation or heating the intake air/ combustion chamber and thus lowering the air/fuel density mixture. The happy zone is the highest temp you can handle before the above issues start limiting you. If that zone requires you to use a lower thermostat then that's what you do.

Since it's highly unlikely you'll find anyone who has done a dyno pull or track run with the only change being the thermostat, it's all going to be circumstantial anecdotes as to what's better for stock or better with a cam change or tune.

You go with the highest temp before predetonation is a very good rule though. Engines are little more than heat pumps and any heat lost into the block is heat not doing any work. Cooler thermostats increase this heat loss, but the idea being it might allow for denser air/fuel mixtures without detonation.
agreed gm engineered the ls motors to run around 200 for peak efficiency, and its and aluminum block with aluminum heads dont worry about stuff thats insignificant im in the middle of the flippin dessert and i had the fans programed a little differently due to that only but 120 degrees will mess with a car...........
Old 02-25-2011, 01:23 PM
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not sure what the LS4's come with but most other LS engines come with a 195*. Setting the fans to come on full blast by 205 has very good results.



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