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

@Tittle Diesel Performance you said larger then stock radiator? I didn't know they made those? 

 

Yes I can see that for a 12v, I tried the holes in the tstat on my 99 and had issues reaching temp. 

 

Really Good information about the offset table. It is ironic that I do notice the difference in idle now that you mention it.

 

On 9/12/2018 at 9:18 PM, pepsi71ocean said:

@Tittle Diesel Performance you said larger then stock radiator? I didn't know they made those? 

 

Yes I can see that for a 12v, I tried the holes in the tstat on my 99 and had issues reaching temp. 

 

Really Good information about the offset table. It is ironic that I do notice the difference in idle now that you mention it.

Yeah if you look at specs some companies make an oversized unit. It’s not displayed as oversized you gotta check the spec sheet. I run 4 core units in both. Stock is 3 according to Chrysler tech bullitens. Either way I’ve never gotten either truck over 190* even with the 1/2 rad block in 70* weather cause I forgot to remove the block. That also includes 20k up 6% grades at 70mph during summer running the AC. They both stay nice and cool all day. I got them dialed. It’s all about the details??

 

Youll notice too that that the clatter is louder on “cold starts” meaning ambient temp. Engines are considered cold under coolant temps of 120-130* depending on manufacture. At 70* ambient VP trucks seem to hold about 18.73* of timing at idle on start to offset for cold fuel and cold air temps as the engine isn’t warm but as it comes up in temp timing falls back to 13.73 roughly. You can hear it if you listen closely. Winter I’m not sure of timing yet though off the top of my head. My dually is new to me still so it hasn’t seen a winter in my possession yet

1 hour ago, Tittle Diesel Performance said:

At 70* ambient VP trucks seem to hold about 18.73* of timing at idle on start to offset for cold fuel and cold air temps as the engine isn’t warm but as it comes up in temp timing falls back to 13.73 roughly.

 

Edge Comp drove that as high as 20 to 22 degrees (highway speed). Then after warm up fell to 12.86 degrees (idle). Hence the IAT fooler this brought it back down to the normal stock realm.