Looking for high MPG in the winter time

[Mopar1973Man]

So I've been playing around with theories. I'm going where most people won't go for economic performance. What have I done this time...

 

• Pulled the 190*F thermostat and replaced it with a 200*F thermostat from a 6.7L Cummins.
• Then install my wintertime grill cover.

 

What happened... Do keep in mind that this is barely just 24 hours after doing this. As for coolant temperatures I'm now up around 203 to 207*F coolant temperatures which now made the IAT rise in temperature floating 90* to 100*F being that 80% of the intercooler is blocked from the direct cold wind and also the manifold is warmer being the coolant jacket run the manifold. I did notice a slight reduction in engine load and EGTs. Engine oil temperature rose slightly from 165*F to 172*F still well below coolant temperature.

 

After studying the air temperature around here winter time can drop into minus temperatures rather quickly and some winters last for weeks. Cold air does affect performance and degrades for daily drivers. My theory is to jump the temperature of the block up to aid in the ignition quality of the fuel and keep the IAT warmer. Even double-check my cruise timing to verify that it's not over-advanced in timing. Be aware future runs and screenshots might have -40*F displayed for the coolant being the Cummins ECM cannot process a temperature above 204*F so at 205*F it flips to -40*F displayed. This is due to the software of the Cummins ECM that starts counting at -40*F and then at 204*F in hexadecimal the value would be 00 to FF. Which is 255 decimal units. Why does the dash show correct? Because the CCD network can count even higher and not bound to the Cummins limitation of software.

 

As for thermal dynamics basically, the rule states that hot is attracted to cold, and cold is attracted to hot things. If you make the coolant jacket hotter there is less heat being dumped into a colder coolant jacket. This puts more energy into the driving wheels. Being the IAT temperature is up more promotes better ignition quality for the fuel which is already high cetane here in Idaho.  As you can see my EGT's are still rather low side and engine load is reduced. But ECO yup is a bit higher now.

 

 I'm going to continue on this path to see how far the rabbit hole goes...

 

NOTE: Transmission Temperature is not that... Transmission Temperature is Engine Oil Temperature measured on top of the oil filter housing. The weather here is roughly 20 to 30*F during this run.

 

[Mopar1973Man]

Ok, update after running to Lewiston Idaho and back home for a monthly shopping trip.

 

I was shocked. It improved the driving response and the MPG is improved. Slight bonus my engine seems quieter running now. EGTs on average are down 50 to 75°F off the average. IAT temperatures are at their worst at +10°F compared to the 190°F thermostat which with cold weather at least stays above 70*F and could top out at about 100*F. I'm going to have to log my MPG and see where this might go. Coolant ranged about 203 to 210°F. Engine oil temperature rose at the worst to 175°F. All in all it was nice to see 125 mile only burning just slightly less than an 1/8 of a tank.