186DEG T STAT
#11
09-13-2007 | 04:17 PM
Senior Member
Joined: Sep 2005
Posts: 143
From:
RE: 186DEG T STAT
This is not true. ECM is mapped for lower fuel consumption at lower temps. additional Fuel cools the engine, so you got it backwards
ORIGINAL: HumminNBoatin
I had a Dodge durango and the Stock one was 180 degrees.I went and bought a 160 Degree Tstat and it did not drop the temp. I thought it would be great for the summer when I am towning the boat and sitting idle at theboat ramp after long hard hauls. In fact it was a pain in the a$$. The computer is dumps more gas into the enginee do get the temp to its stock operating temp. Therefore the getting a colder TStat is not only an initail waste of money but its costs you more to role down the road. I went from getting 11.5mpg in my Durango to 9mpg when I did this. If the computer can be changed to match it great. But I have learned my lesson on this with Computerized engines.
I had a Dodge durango and the Stock one was 180 degrees.I went and bought a 160 Degree Tstat and it did not drop the temp. I thought it would be great for the summer when I am towning the boat and sitting idle at theboat ramp after long hard hauls. In fact it was a pain in the a$$. The computer is dumps more gas into the enginee do get the temp to its stock operating temp. Therefore the getting a colder TStat is not only an initail waste of money but its costs you more to role down the road. I went from getting 11.5mpg in my Durango to 9mpg when I did this. If the computer can be changed to match it great. But I have learned my lesson on this with Computerized engines.
#13
09-13-2007 | 05:25 PM
Super Moderator
Joined: Jul 2007
Posts: 12,493
From: Boat Town USA MI
RE: 186DEG T STAT
There are power gains in specific applications witha T stat change to a lower rating, but not all. 
There are a multitude of cons in doing this however. 
Todays computers moniter water temp (man a few even monitor oil temp) and cross reference MAF (mas air flow: isnotreally equal to avolume mesure) and MAP (Manifold absolute pressure) readings, with the oxygen sensor in the exhaust to form a full loop of data to control timing and fuel ratio. MAFs also incorporate air temperatureof the intake charge to the reading at the MAP with the engine RPM to determine complete air density. Dense air has a larger combustion volume so more fuel can be injected to create more power. All this is instantaneous. Easy enough?
The theory of a T Stat change is to lower engine temperature to increase air density, allowing more fuel = power, and at the same time tell the PCM/ECM not to retard timing. Power makes heat. Heat tells the PCM/ECM to retard timing to make less power maintain proper temper. Viscious cycle aye! It does work. Short term benefit to be sure.
However, the biggest con is the T stat takes engine heat and shifts it to the radiator. [:@] The heat is still there, it just got moved making the radiator work harder to keep balance. Your radiator and coolant take a long term beating, big time!!!! [:@] The extra radiator heat can get refracted into the auto trans long term also, not good! [:@] Run the A/C and it adds to this long term problem. [:'(] Sorry for boring the daylights out of everybody. [8D]
You know those cheap azz "power sensors" that you can get on ebay, all they do is (change the voltage) trick your PCM/ECM into thinking the MAF is reading a cooler air charge to allow for a higher fuel ratio and keep the timing advanced. The success probability of any benifit there is slim to none because the rest of the complete loop is running like always and the heat is still there.
IMO, there are better ways to make power than just beating up your cooling system.
There are a multitude of cons in doing this however. Todays computers moniter water temp (man a few even monitor oil temp) and cross reference MAF (mas air flow: isnotreally equal to avolume mesure) and MAP (Manifold absolute pressure) readings, with the oxygen sensor in the exhaust to form a full loop of data to control timing and fuel ratio. MAFs also incorporate air temperatureof the intake charge to the reading at the MAP with the engine RPM to determine complete air density. Dense air has a larger combustion volume so more fuel can be injected to create more power. All this is instantaneous. Easy enough?
The theory of a T Stat change is to lower engine temperature to increase air density, allowing more fuel = power, and at the same time tell the PCM/ECM not to retard timing. Power makes heat. Heat tells the PCM/ECM to retard timing to make less power maintain proper temper. Viscious cycle aye! It does work. Short term benefit to be sure.
However, the biggest con is the T stat takes engine heat and shifts it to the radiator. [:@] The heat is still there, it just got moved making the radiator work harder to keep balance. Your radiator and coolant take a long term beating, big time!!!! [:@] The extra radiator heat can get refracted into the auto trans long term also, not good! [:@] Run the A/C and it adds to this long term problem. [:'(] Sorry for boring the daylights out of everybody. [8D]
You know those cheap azz "power sensors" that you can get on ebay, all they do is (change the voltage) trick your PCM/ECM into thinking the MAF is reading a cooler air charge to allow for a higher fuel ratio and keep the timing advanced. The success probability of any benifit there is slim to none because the rest of the complete loop is running like always and the heat is still there.
IMO, there are better ways to make power than just beating up your cooling system.
#14
09-13-2007 | 10:07 PM
Senior Member
Joined: Sep 2007
Posts: 727
From:
RE: 186DEG T STAT
ORIGINAL: Doc Olds
There are power gains is specific applications with T stat change to a lower rating, but not all. There are a multitude of cons in doing this however.
Todays computers moniter water temp (man a few even monitor oil temp) and cross reference MAF (mas air flow: isnotreally equal to avolume mesure) and MAP (Manifold absolute pressure) readings, with the oxygen sensor in the exhaust to form a full loop of data to control timing and fuel ratio. MAFs also incorporates air temperatureof the intake charge to the reading at the MAP with the engine RPM to determine complete air density. Dense air has a larger combustion volume so more fuel can be injected to create more power. All this is instantaneous. Easy enough?
The theory of a T Stat change is to lower engine temperature to increase air density, allowing more fuel = power, and at the same time tell the PCM/ECM not to retard timing. Power makes heat. Heat tells the PCM/ECM to retard timing to make less power maintain proper temper. Viscious cycle aye! It does work. Short term benefit to be sure.
However, the biggest con is the T stat takes engine heat and shifts it to the radiator. [:@] The heat is still there, it just got moved making the radiator work harder to keep balance. Your radiator and coolant take a long term beating, big time!!!! [:@] The extra radiator heat can get refracted into the auto trans long term also, not good! [:@] Run the A/C and it adds to this long term problem. [:'(] Sorry for boring the daylights out of everybody. [8D]
You know those cheap azz "power sensors" that you can get on ebay, all they do is (change the voltage) trick your PCM/ECM into thinking the MAF is reading a cooler air charge to allow for a higher fuel ratio and keep the timing advanced. The success probability of any benifit there is slim to none because the rest of the complete loop is running like always and the heat is still there.
IMO, ther are better ways to make power than just beating up your cooling system.
There are power gains is specific applications with T stat change to a lower rating, but not all. There are a multitude of cons in doing this however.
Todays computers moniter water temp (man a few even monitor oil temp) and cross reference MAF (mas air flow: isnotreally equal to avolume mesure) and MAP (Manifold absolute pressure) readings, with the oxygen sensor in the exhaust to form a full loop of data to control timing and fuel ratio. MAFs also incorporates air temperatureof the intake charge to the reading at the MAP with the engine RPM to determine complete air density. Dense air has a larger combustion volume so more fuel can be injected to create more power. All this is instantaneous. Easy enough?
The theory of a T Stat change is to lower engine temperature to increase air density, allowing more fuel = power, and at the same time tell the PCM/ECM not to retard timing. Power makes heat. Heat tells the PCM/ECM to retard timing to make less power maintain proper temper. Viscious cycle aye! It does work. Short term benefit to be sure.
However, the biggest con is the T stat takes engine heat and shifts it to the radiator. [:@] The heat is still there, it just got moved making the radiator work harder to keep balance. Your radiator and coolant take a long term beating, big time!!!! [:@] The extra radiator heat can get refracted into the auto trans long term also, not good! [:@] Run the A/C and it adds to this long term problem. [:'(] Sorry for boring the daylights out of everybody. [8D]
You know those cheap azz "power sensors" that you can get on ebay, all they do is (change the voltage) trick your PCM/ECM into thinking the MAF is reading a cooler air charge to allow for a higher fuel ratio and keep the timing advanced. The success probability of any benifit there is slim to none because the rest of the complete loop is running like always and the heat is still there.
IMO, ther are better ways to make power than just beating up your cooling system.
#15
09-14-2007 | 12:07 AM
Senior Member
Joined: Sep 2005
Posts: 143
From:
RE: 186DEG T STAT
Hey Doc, sounds like you got some of it straight, but a few. The lower temp thermostat allows cooler liquid to leave the engine and into the radiator sooner as the fluid is leaving the engine at the temp of the new thermostat and not of the higher thermostat that would be taken out. So in reality, the temps in the cooling system are at a lower starting point to begin with, prior to commencing the cooling process within the cooling system. Overal cooling system temps are determined by the efficiency of the radiator and engine temps are held up until the Thermostat opens and then is ultimately determine by overall cooling system efficiency.
Other thing is the MAF does not send intake temps to ECM, as this is done at the throttle body (and so is M.A.P), thus the reason for the the Coolant Bypass Kits that are out there. MAF meters air and thus adds fuel according so O2 sensor then detects AFR as set in the ECM base map.
Other thing is the MAF does not send intake temps to ECM, as this is done at the throttle body (and so is M.A.P), thus the reason for the the Coolant Bypass Kits that are out there. MAF meters air and thus adds fuel according so O2 sensor then detects AFR as set in the ECM base map.
#16
09-14-2007 | 12:44 AM
Senior Member
Joined: Jun 2005
Posts: 3,600
From:
RE: 186DEG T STAT
how do you figure the temp is lower leaving the engine? doesn't the t-stat open and let cool water into the engine at it's specified temp? how does that relate to the temp coming out? if i pump 180 degree water into a hot engine and it heats it up to 250 before leaving, i would hope i have a damn good cooling system so it's below 180 on the way back in. the h2 doesn't have that kind of cooling system, in fact it's barely servicable.
#17
09-14-2007 | 11:40 AM
Super Moderator
Joined: Jul 2007
Posts: 12,493
From: Boat Town USA MI
RE: 186DEG T STAT
Dude, there ain't enough space to tech how the whole system works, so I did a very brief overview. GM MAFs sense temp. READ http://www.kemparts.com/TechTalk/tt06.aspfor a tiny little overview. They don't SEND a temperature reading to the PCM, they send a voltage reading based upon temperature. So technically what you said is correct Tomp. But does a GM MAF send a temperature readingto the PCM/ECM???? Huh, do it? what?, I CAN'T HEAR YOU!!!! Does it matter to understand how the T Stat palys a role when the measure is a temperature driven voltage to calculate air mass??? Uh.........no.
A lower temp T stat sends water to the radiator earlier than a higher temp stat. Yep. Thats what I said, the heat gets shifted to the cooling sytem out of the engine. The cooler T Stat sendswater to the radiator more often under load as the engine creates power. Where do it go??? To the cooling system. Just cuz the cooler stat opens at, let's say 160F, do you think all thecoolant from the engine is 160F????? Of course not, the stat opens at 160, the water temp is actally above that, that's whysome guys posted they didn't notice a change in temp at the guage. Radiators can cool up to a certain volume, run at max volume or close for extended periods and, in my book that is beating up the cooling system.
So, what you are suggesting I missed didn't really get missed at all.[8D] I agree with your observation "the temps in the cooling system are at a lower starting point to begin with, prior to commencing the cooling process within the cooling system. Overal cooling system temps are determined by the efficiency of the radiator and engine temps are held up until the Thermostat opens and then is ultimately determine by overall cooling system efficiency. "
The problem is, the efficiency of the cooling system was designed to run lower volumes of coolant even though that coolant may be 10-15F higher in temp. Short term, it works, long term you pay for it in your cooling system. Thanks Tomp. You made me overkill this silly stuff again. [sm=icon_blah.gif]
. But does a GM MAF send a temperature readingto the PCM/ECM???? Huh, do it? what?, I CAN'T HEAR YOU!!!! Does it matter to understand how the T Stat palys a role when the measure is a temperature driven voltage to calculate air mass??? Uh.........no.A lower temp T stat sends water to the radiator earlier than a higher temp stat. Yep. Thats what I said, the heat gets shifted to the cooling sytem out of the engine. The cooler T Stat sendswater to the radiator more often under load as the engine creates power. Where do it go??? To the cooling system. Just cuz the cooler stat opens at, let's say 160F, do you think all thecoolant from the engine is 160F????? Of course not, the stat opens at 160, the water temp is actally above that, that's whysome guys posted they didn't notice a change in temp at the guage. Radiators can cool up to a certain volume, run at max volume or close for extended periods and, in my book that is beating up the cooling system.
So, what you are suggesting I missed didn't really get missed at all.[8D] I agree with your observation "the temps in the cooling system are at a lower starting point to begin with, prior to commencing the cooling process within the cooling system. Overal cooling system temps are determined by the efficiency of the radiator and engine temps are held up until the Thermostat opens and then is ultimately determine by overall cooling system efficiency. "
The problem is, the efficiency of the cooling system was designed to run lower volumes of coolant even though that coolant may be 10-15F higher in temp. Short term, it works, long term you pay for it in your cooling system. Thanks Tomp. You made me overkill this silly stuff again.
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