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Discussion Starter #21
..... Although no CEL came on when you swapped to a lower temperature your car isn't burning as clean.
Hehehe! So you don't trust the electronics? How you define then "...as clean"? Let me have bigger concerns than that! Unless... you are driving a full electrical car and have solar panels all around your house and recycle the water you use on daily basis?:th_angelsmiley4:

There are pros and cons but I work in the field and believe me not all the released products on the market are based on proven ideas and detailed tests.
I checked the thermostats for major passenger cars today and tell me if you can find one that is opening over 100C! I couldn't find any! Ideally I would put a thermostat that opens around 90-92C max but couldn't find a direct replacement and didn't want also to change the housing, adapters etc. I'm not going to argue more about "performances & emissions", I just shared my work and the results so others can decide if they want to do or not the swap since the gauge for coolant temperature is useless and you boil the coolant without even knowing it, zero warnings! :wave:
 

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Question: What would be the effect of just changing the cap to 15lbs? That 25% reduction in system pressure seems where most of the benefit comes from. As far as I can tell, the boiling point would be 267F down from 282F. (This is for generic 50% antifreeze - I couldn't find a table for Dexcool.)

Edit: For Dexcool, it's 260F/266F/277F depending on 40%/50%/70% mixture at 15lbs. I don't know what it is for 20lbs.

What hasn't been addressed is the temperature gauge that doesn't give good warnings. That's going to take a computer solution.
 

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Question: What impact has running cooler had on your emissions? Part of the reason the Cruze runs so hot is for emissions purposes - hotter engines tend to burn cleaner.
Hotter engines run dirtier. They produce more NOX.

Running an engine at 220* must have some pretty high levels.
 

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Discussion Starter #26
Question: What would be the effect of just changing the cap to 15lbs? That 25% reduction in system pressure seems where most of the benefit comes from. As far as I can tell, the boiling point would be 267F down from 282F. (This is for generic 50% antifreeze - I couldn't find a table for Dexcool.)

Edit: For Dexcool, it's 260F/266F/277F depending on 40%/50%/70% mixture at 15lbs. I don't know what it is for 20lbs.

What hasn't been addressed is the temperature gauge that doesn't give good warnings. That's going to take a computer solution.
In theory, yes, it is better to have a higher pressure into the system. But in reality the extra pressure damages the hoses, connections, expansion tank, etc. See how many issues are related with that on this forum. Look around to other similar cars and see the cap spec. I monitored long enough the system and the active grille shutter has also influence on controlling the coolant temperature. Not efficient at all under different circumstances, when for example the grille it is locked into a random positions due to the outside temperature. That is another story, they dropped also this extra feature that was very advertised when they came in US with the first Cruze generation. I have mercury tilt switch on the grille connected to an LED inside the car so during the years I could daily monitor its behavior. The thermostat for the first Gen is also "smart" so the computer supposed to properly control the temperature and open/close the thermostat and grille based on different algorithms. The intention was good but not efficient in my opinion....
 

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In theory, yes, it is better to have a higher pressure into the system. But in reality the extra pressure damages the hoses, connections, expansion tank, etc.
Right. I get that. The question is if it's safe to run lower pressure without changing the thermostat. I'm not sure what the peak temperature would be and how much margin is needed.
 

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Discussion Starter #28 (Edited)
Right. I get that. The question is if it's safe to run lower pressure without changing the thermostat. I'm not sure what the peak temperature would be and how much margin is needed.
You just need to keep the coolant from boiling. The boiling point is related to temperature, pressure and % mixture of your coolant (and type of coolant). You can find all these then do the math. :)

Boiling.JPG
 

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modifying the thermostat without adapting the software tune will cause trouble codes... the ECM controls the thermostat to a desired ECT and will set a DTC and MIL if it does not see that temperature after a certain time
 

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modifying the thermostat without adapting the software tune will cause trouble codes... the ECM controls the thermostat to a desired ECT and will set a DTC and MIL if it does not see that temperature after a certain time
None yet with mine.

Sent from my PH-1 using Tapatalk
 

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The 1.4T engine in the 2nd generation Cruze isn't the same engine as the one in your Cruze. While the Volt's 1.4 engine in the Gen 1 Volt is the same base engine, it never runs as hard as the one in the Cruze does and in fact never exceeds 4500 RPM. The engine tuning in the two cars is dramatically different.

As for being aware of emissions, you would be aware of them as well if you drove under an electronic highway sign every day and over half the days of the year it's urging you to not drive because of air quality problems. Although no CEL came on when you swapped to a lower temperature your car isn't burning as clean.
UPDATE:
i had an emissions test done yesterday for registration and car PASSED
 

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Hotter engines produce more NOx.

I'd like to know how you all get 250 degree oil out of 180 degree coolant.

I've yet to see my oil get hotter then water.
In fact. I've yet to see it come close to water.

Even my semi don't get hotter oil climbing the mountains. Fan kicks on at 215. Hottest I've seen oil is 210. And it all cools right back down on the down hill side.
 

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Unless you have an oil temperature gauge, what are you basing your oil temperature on? Unless things have changed it has been my belief that oil temperature is not influenced very much by normal engine temperature. After all there is an oil cooler in the radiator for the transmission. Doesn't that then indicate the the oil is hotter than the coolant?
 

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OIl gets it's heat from the engine. How can you make it hotter then the engine? Water heats up faster then oil.

Car has obd. Semi has gauge.

Not only do you have a cooler. You also have air flow around the pan.
 

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OIl gets it's heat from the engine. How can you make it hotter then the engine? Water heats up faster then oil.

Car has obd. Semi has gauge.

Not only do you have a cooler. You also have air flow around the pan.
Oil gets its heat from friction. Any engine temp gauge will show either water or oil temp. Oil temp can vary greatly depending on where the sensor is placed, after oil cooler or immediately after heat source which is bearings, piston rings, etc.
 

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OIl gets it's heat from the engine. How can you make it hotter then the engine? Water heats up faster then oil.
Oil temperature is not connected to water temperature, the combustion of the cylinders is the main source of engine temperature. The old air cooled engines still heated up the oil because all the moving components generate heat. The oil in the gearbox (manual) and diff in a rear wheel drive race car require oil coolers to stop the oil overheating and failing.
 

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OIl gets it's heat from the engine. How can you make it hotter then the engine? Water heats up faster then oil.
Oil temperature is not connected to water temperature, the combustion of the cylinders is the main source of engine temperature. The old air cooled engines still heated up the oil because all the moving components generate heat. The oil in the gearbox (manual) and diff in a rear wheel drive race car require oil coolers to stop the oil overheating and failing.
Air cooled is a different beast and yes oil is connected to water. It heats and cools along side with water.
 
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