Everyone knows I just did a coolant flush not to long ago and change my thermostat for the 190*F from NAPA. Come to find out the new thermostat tend to lean on the high side of the 190's. No problem. MPG numbers seemed good. I started to wonder about if I changed the thermostat from 190*F to 180*F if the IAT would follow? Guess what it does. Instead of the constant +40*F offset the 180*F makes roughly a +30*F offset with 80*F outside temp the IAT floated 105-110*F. If your looking for colder IAT temps then the thermostat will give you at least -10*F drop. This was only a 30 mile round trip to town. I'll leave it in and watch the IAT and ECT closely for the next few days.

 

I'm going to bet I'm going to take an MPG hit because of thermodynamic and too much heat energy will be lost to the coolant being colder. We'll see, won't we? 

 

Here is some photos. Part number for NAPA.

 

Old version of the 190*F thermostat versus the new version on the right.

 

Edited August 31, 20186 yr by Mopar1973Man

I don't think you will see anything negative. 180 thermostats were the norm until emissions got in the way. At -30 the cab heat might suffer. I went to a 180 this summer for the first time and I am seeing cooler temps on everything associated with engine block/under hood temperature heat sink. Even my transmission. So far I am very comfortable with the change.

Being I keep a full fuel log since 20k miles. I'm sure I'll spot how much of a loss is possible. 

 

 

Looks like I need to catch up with August part of the logs...

So far this morning travelling through New Meadows ID it was mere 35F for morning air temp. The IAT offset was still up there about 45 to 50 degrees. Neat part as I got closer to Weiser and the outside temp rose to 65 then the IAT was sinking fast on offset. I'd find that turbo cool down is much faster. The down side when idling the coolant can drop to 178F and the EGT are in low 200's which in the dead of winter is a bad thing. Idle speed is up nearly a full 10 RPM.

I ran Cummins 180 in mine many years ago and never noticed much difference in how the operated.

 

 I need some of the cooler weather you are seeing. Still in the low to mid 90's with 90% humidity out this way. 

Ontario, OR

At least tell me the humidity is low @Mopar1973Man.

I remember a while back @pepsi71ocean experimented with a 200 degree thermostat and I seem to remember it helped his fuel mileage. I needed a new thermostat in the 01 in around 2013 and went to Cummins and got a 200* thermostat. I've never installed my scanguage or anything to monitor sensor data and honestly don't know if it really did anything fuel mileage wise. What I do notice is awesome heat output from the HVAC in the winter. I've been running the 200* thermostat year round for 5 years.

I kind of screwed up tonight. I was thinking about getting fuel for the truck and find out what the MPG on 180*F thermostat would be, then drove right on by the fuel station. Shocking enough I've got enough fuel yet to turn around and return to Ontario, OR. I'm right about needle width below 1/2 tank (18.x gallons used). I was kind of shocked at the IAT temps watching closely for the day. City stop and go it would average +40*F or so over outside. Once I was on the highway making a bit of boost the IAT fell to about +30*F over outside. Coming home once the temperature started to cool towards 70*F it started inching its way into the high +20*F and swinging back to +30 offset. So I'll get fuel tomorrow so I'm not running around on fumes for the weekend. 

 

35 minutes ago, 04Mach1 said:

What I do notice is awesome heat output from the HVAC in the winter.

 

My old 190*F thermostats always produced at least 160*F air from the center vents. 

 

37 minutes ago, 04Mach1 said:

've never installed my scanguage or anything to monitor sensor data and honestly don't know if it really did anything fuel mileage wise.

 

I've been doing the standard hand math vs what data feed I get from the Quadzilla.

This wasn't on a diesel but a small block mopar, the high temperature T stat change on an engine dyno actually lost power at 195* vs 160 without changing the AFR and IAT temps were the same ambient on both tests. The engine builder suggested the extra heat around the piston caused it to grow and ring end gap to close up which ended up creating more friction. In fact every part of the engine was growing and closing clearances creating drag. Granted closer tolerances are usually a good thing but it also creates in cylinder heat issues as well. Diesels aren't effected nearly as much in that way but take into account the oil temp, piston temp and head will all run hotter which means your heat soak will increase and therefore EGT safe peak technically can technically be reduced do to lesser piston, rod, skirt and ring cooling. They are designed to run hot yes but just know you can overheat the piston easier now. I run 180's in my 12 and 24v both to aleaviate this. Specially in diesel applications the thinning of the hoter oil doesn't pay off in less drag coefficient if the piston swell creates more drag. Essentially it'll offset the gains your looking for. 180 operational degrees is what the engine was originally clearanced and calculated for. 

 

That said if im wrong I'll be impressed lol I know my 12v ran worse with a 195* vs a 180. Too much heat soak and EGT suffered

29 minutes ago, Mopar1973Man said:

 

I've been doing the standard hand math vs what data feed I get from the Quadzilla.

I've always been horrible about routinely checking fuel mileage in any of my vehicles. I can usaully go from Grants, NM to my mother-in-law house in Aurora, CO on about 25-26 gallons of fuel which is about 21-22 mpg in the 01. I've got a scanguage brand new in the box that I could monitor some data with if I'd just use it.

 

6 hours ago, 04Mach1 said:

I remember a while back @pepsi71ocean experimented with a 200 degree thermostat and I seem to remember it helped his fuel mileage. I needed a new thermostat in the 01 in around 2013 and went to Cummins and got a 200* thermostat. I've never installed my scanguage or anything to monitor sensor data and honestly don't know if it really did anything fuel mileage wise. What I do notice is awesome heat output from the HVAC in the winter. I've been running the 200* thermostat year round for 5 years.

 

While my mpg did improve it wasn't anything much to write home about. I'm still running my 200f in my truck and the scan gauge reads a consistent 193-202f with a peak of 210. 

 

But yes the HVAC box will melt your face off with a 200f in it.

 

6 hours ago, Mopar1973Man said:

My old 190*F thermostats always produced at least 160*F air from the center vents. 

 

This is a different level of heat Mikey. I kid you not I can see 175+ out of my vents when it's below freezing out.  It's nice feeling hot in the cab in no time, even on defrost.

 

6 hours ago, Tittle Diesel Performance said:

This wasn't on a diesel but a small block mopar, the high temperature T stat change on an engine dyno actually lost power at 195* vs 160 without changing the AFR and IAT temps were the same ambient on both tests. The engine builder suggested the extra heat around the piston caused it to grow and ring end gap to close up which ended up creating more friction. In fact every part of the engine was growing and closing clearances creating drag. Granted closer tolerances are usually a good thing but it also creates in cylinder heat issues as well. Diesels aren't effected nearly as much in that way but take into account the oil temp, piston temp and head will all run hotter which means your heat soak will increase and therefore EGT safe peak technically can technically be reduced do to lesser piston, rod, skirt and ring cooling. They are designed to run hot yes but just know you can overheat the piston easier now. I run 180's in my 12 and 24v both to aleaviate this. Specially in diesel applications the thinning of the hoter oil doesn't pay off in less drag coefficient if the piston swell creates more drag. Essentially it'll offset the gains your looking for. 180 operational degrees is what the engine was originally clearanced and calculated for. 

 

That said if im wrong I'll be impressed lol I know my 12v ran worse with a 195* vs a 180. Too much heat soak and EGT suffered

 

Engine coolant temperatures will change fueling and timing on a VP truck. We run hotter stats in the trucks at work.  But there issues I have with running colder comes from tar buildup in the valves. I'll trade off a little idle time for a lower risk of tar buildup.

That's my worry with 180F thermostat. The EGTs are much lower idling in 35F weather. Engine temp sank to 177F I would be concerned with tar issues on the valves in the dead of winter.

6 hours ago, Mopar1973Man said:

That's my worry with 180F thermostat. The EGTs are much lower idling in 35F weather. Engine temp sank to 177F I would be concerned with tar issues on the valves in the dead of winter.

 

It's been years since I put it in, but my Cummins still idles 197-202 on coolant temps, and even pulling I see 200-210. For cold weather operation I think it's ideal. Even in places like PA where I was working it would get down into 0-10f Mark.

So what I'm getting from this is it's best to leave 190 alone and it should do good in summer and winter both. 

49 minutes ago, Dieselfuture said:

So what I'm getting from this is it's best to leave 190 alone and it should do good in summer and winter both. 

 

Unless your seeing very hot temperatures I see no harm in running a 200f tstat. The cooling system will easily handle the temperature, and dump extra heat quicker then it could overheat. IMO. 

 

Even in the winter I think your in Iowa, I think you would like the extra heat in the winter. 

 

It's worth the money to try it. If not you can always swap tstats back and fourth. It's very easy to do in our trucks and doesn't require you to dump the coolant to find out.

 

If you do decide to, let me know I'm going to write an article about it if you post back good results.

 

I should say that while my mpg did increase, it's hard to tell it here in the East coast where your routinely running 80mph wound out because people out here have attitude issues. Combined with larger injectors and a S03, who really knows. The scan gauge showed a huge change because the IAT would stay warmer and even with the cool weather still would hold up better, when the weather starts dropping into the 50s and such I'll still see warmer IATs then before.

On 9/2/2018 at 3:36 AM, Mopar1973Man said:

That's my worry with 180F thermostat. The EGTs are much lower idling in 35F weather. Engine temp sank to 177F I would be concerned with tar issues on the valves in the dead of winter.

 

I wouldn't worry much about tar issues, yes EGT is much much lower but you gotta think the valve exhaust temp passing over it is still near 300-400* it just cools extremely fast moving threw the manifold under low pressure at idle. If your developing carbon or tar then you have some other issues to worry about.

 

this is all based on a stock or programmed truck with an IAT map also where quads don't have that offset table. Being that the original engine design operation range is 160-220 you shouldn't see mass carbon building in the engine. If it idled every day 24/7 then yeah sure since EGT would never rise and a potential dirty burn would occur.

 

9 hours ago, pepsi71ocean said:

 

Unless your seeing very hot temperatures I see no harm in running a 200f tstat. The cooling system will easily handle the temperature, and dump extra heat quicker then it could overheat. IMO. 

 

Even in the winter I think your in Iowa, I think you would like the extra heat in the winter. 

 

It's worth the money to try it. If not you can always swap tstats back and fourth. It's very easy to do in our trucks and doesn't require you to dump the coolant to find out.

 

If you do decide to, let me know I'm going to write an article about it if you post back good results.

 

I should say that while my mpg did increase, it's hard to tell it here in the East coast where your routinely running 80mph wound out because people out here have attitude issues. Combined with larger injectors and a S03, who really knows. The scan gauge showed a huge change because the IAT would stay warmer and even with the cool weather still would hold up better, when the weather starts dropping into the 50s and such I'll still see warmer IATs then before.

 

Ive done the back and forth swap and yes that's an option but another easier solution for you cold weather guys is cutting the top off a pizza box and doing a radiator block between the intercooler and radiator. In the winter (10-40*f range) I run a 3/4 block typically unless towing then it's usually a 1/2 block temp depending. This will hold a lot more heat in and keep efficacy up due to lack of fan draw since it's got very little air to draw on so it stays in a low pressure area. It's much faster then doing a T stat change and you can usually keep it 180-190* or so on a 180 T stat mostly due to heat soaking and under hood temps keep up with the lesser air flow from the fan. Just give it a shot if your engine is cold or has a hard time warming up.

 

part of that is I drill a .055 .079" hole in the thermostat too for temp fluctuation reduction. Specially 12v vehicles to keep the block or head from warping or spitting a freeze plug. It takes a little longer to warm up but with the rad block it's pretty quick and give you control. I've never overheated or even broke 200* with that block just don't forget to remove it in the spring!

1 minute ago, Tittle Diesel Performance said:

ve done the back and forth swap and yes that's an option but another easier solution for you cold weather guys is cutting the top off a pizza box and doing a radiator block between the intercooler and radiator.

 

I don't suggest that. This potentially can lead to overheating. I've actually had that happen this why I will not cover the face of the intercooler or the radiator. I will cover the grill this allows the fan to lock when needed to pull air through the intercooler and the radiator without any concern. Like my current weather starting to dip down to the 30's for the morning but can rise well into the 90's by afternoon. With a grill covers you can actually still drive with 80*F temps without any issues and not have to constantly remove and install the winter front because of fluke warm day. Typically I install my grill covers by October and leave them in all winter till April.  

 

8 hours ago, Tittle Diesel Performance said:

 

I wouldn't worry much about tar issues, yes EGT is much much lower but you gotta think the valve exhaust temp passing over it is still near 300-400* it just cools extremely fast moving threw the manifold under low pressure at idle. If your developing carbon or tar then you have some other issues to worry about.

 

Cummins came out with a tab about this issue. But even so I have larger injectors and I can see pyrometer temps in the 180 range at idle in the dead of winter with a 190 Napa stat. It's too choose to wet stacking for me.

 

8 hours ago, Tittle Diesel Performance said:

This is all based on a stock or programmed truck with an IAT map also where quads don't have that offset table. Being that the original engine design operation range is 160-220 you shouldn't see mass carbon building in the engine. If it idled every day 24/7 then yeah sure since EGT would never rise and a potential dirty burn would occur.

 

What do you mean by "off set programming" I have a smarty.

 

8 hours ago, Tittle Diesel Performance said:

 

Ive done the back and forth swap and yes that's an option but another easier solution for you cold weather guys is cutting the top off a pizza box and doing a radiator block between the intercooler and radiator. In the winter (10-40*f range) I run a 3/4 block typically unless towing then it's usually a 1/2 block temp depending. This will hold a lot more heat in and keep efficacy up due to lack of fan draw since it's got very little air to draw on so it stays in a low pressure area. It's much faster then doing a T stat change and you can usually keep it 180-190* or so on a 180 T stat mostly due to heat soaking and under hood temps keep up with the lesser air flow from the fan. Just give it a shot if your engine is cold or has a hard time warming up.

 

I did that years ago before I built a winter front. I was it in a snow storm and lost my ad and couldn't keep the windshield clean, and then had snow and ice buildup over the ac and transmission coolers. 

 

8 hours ago, Tittle Diesel Performance said:

part of that is I drill a .055 .079" hole in the thermostat too for temp fluctuation reduction. Specially 12v vehicles to keep the block or head from warping or spitting a freeze plug. It takes a little longer to warm up but with the rad block it's pretty quick and give you control. I've never overheated or even broke 200* with that block just don't forget to remove it in the spring!

 

The fluctuations on a 12v are due to the location of the proble. On my vp truck I found some stats cycle worse then others.  I had cummins 180s that would cycle 172-187, but I ran Napa 190s that would cycle 185-195. 

 

For me running around in 0-35f weather the 200 seems to put out a significantly more heat compared to the other two without putting it on recalculate.

On 9/3/2018 at 6:36 PM, pepsi71ocean said:

 

Cummins came out with a tab about this issue. But even so I have larger injectors and I can see pyrometer temps in the 180 range at idle in the dead of winter with a 190 Napa stat. It's too choose to wet stacking for me.

 

 

What do you mean by "off set programming" I have a smarty.

 

 

I did that years ago before I built a winter front. I was it in a snow storm and lost my ad and couldn't keep the windshield clean, and then had snow and ice buildup over the ac and transmission coolers. 

 

 

The fluctuations on a 12v are due to the location of the proble. On my vp truck I found some stats cycle worse then others.  I had cummins 180s that would cycle 172-187, but I ran Napa 190s that would cycle 185-195. 

 

For me running around in 0-35f weather the 200 seems to put out a significantly more heat compared to the other two without putting it on recalculate.

The offset table is an overlay map, I believe smarty leaves that alone but when IAT changes the timing variable and fuel map changes for offset in oxygen content and heat rise during compression. Essentially it dials fuel back a little when it's hot and timing falls to control combustion pressures. It's all for emissions, the quadzilla doesn't use that factor in it's program but smarty and superchips both do since there a flash program. Really that table isn't a bad thing to have, it can save a head gasket if you run the boarder edge of timing at say 70* IAT then at 140* IAT due to to much timing. It can create too much pressure and too fast of a flame front. You'll notice summer to winter that the engine clatter changes. When my tow rig IAT went past 140* with the super chips timing fell hard, engine went near silent once it hit 150 at cruising conditions. This was on an eco tune that ran a TON of timing just like the smarty eco map.

 

 

as for the 12v yeah the location of the temp probe is an issue but that fluctuation does occur upon the T stat opening and in some cases can crack heads. Doesn't happen often and it's usually operator error by heating the engine too fast in the cold. The drilled hole takes a bit longer to warm up but it's much smoother and easier on components not to be shocked by a cold flow of water. It's designed to withstand it yes but it's more of a safeguard.

 

warmer temp in the winter is no question beneficial but radiator or grille blocking helps a lot too just blocking cold air in the engine compartment alone will help a lot. Each is different though and of course your geographical location

On 9/3/2018 at 10:05 AM, Mopar1973Man said:

 

I don't suggest that. This potentially can lead to overheating. I've actually had that happen this why I will not cover the face of the intercooler or the radiator. I will cover the grill this allows the fan to lock when needed to pull air through the intercooler and the radiator without any concern. Like my current weather starting to dip down to the 30's for the morning but can rise well into the 90's by afternoon. With a grill covers you can actually still drive with 80*F temps without any issues and not have to constantly remove and install the winter front because of fluke warm day. Typically I install my grill covers by October and leave them in all winter till April.  

 

That's a good way of doing it too, the pizza box trick you don't cover the hole thing just half, and you can adjust how much you need. Usually below 30*f I do 1/2 running empty and towing I remove it unless temp gets too low then I'll go 1/4. Helps with warmup too with the T stat drilled. Never had an overheat issue and I'm pretty on top of it depending on conditions. I have a lot of idle time in the winter, this holds the heat in really well and self regulates the temp more. Both my trucks have larger then stock radiators according to specs. It's got an additional core on each truck to offset for added EGT and cylinder temps. Better too cold then too hot (to a point)