lower degree thermostat

[mechtech2]

If the intake temp was 16 degrees cooler, it shows why the oil is running cooler.
It had to be cooler outside - the ambient temps were less.
Add this to whatever varied driving condition there were.

 

[tonycarguy]

I wouldn't muck around with the therm. Modern cars are heavily computer controlled and rely on data input to make various decisions. Unless you're 100% certain the ECU isn't using coolant temperature to make some decisions or that coolant temp doesn't somehow affect something else that the ECU reads, I would leave it alone.

 

[SteveSRT8]

Late model Hemis, either 5.7 or 6.1, are notoriously affected by temps. We have one of each in the family, and I have a lot of miles in both.

They both become complete dogs if allowed to reach what are considered normal temps in any other car/truck I own. The 5.7 is a bit less affected, but you can feel it get 'boggy' when the coolant is over 200. The 6.1 is hugely affected, and starts pulling significant timing at under 190 degrees!

Since these vehicle ship with a factory 203 stat, an easy mod for power is a 180 thermo. If you use one that spikes over 180 at warm up you won't throw codes, and a VERY small loss of fuel economy is the only downside. The oil still reaches 205-225 in normal driving, even in a 5.7.

For most enthusiast drivers the huge increase in timing will be felt and appreciated.

 

[mechtech2]

Steve - Sounds like you know these cars!
They must have bad programming - what were they thinking?
A performance car that is castrated when it reaches operating temperature??
This is an oddball situation, and probably in this case the 180 fix is appropriate.
For most cars, it is not recommended.

 

[SteveSRT8]

yeah, it's related to the decrepit head design. They flow very well but are prone to detonation, then factor in the fragile pistons with thin lands that go boom at the slightest ping. Don't get me wrong, it still runs pretty well, but the difference is huge.

It's typical factory programming, set up for the worst possible conditions but leaving a TON of HP/Torque on the table!

 

[renos09ram]

Steve, I thought the 5.7 came with a 195 degree thermostat? So are you saying I will be fine by changing it to a 180 degree thermostat? What about winter time, will I be okay. or will I have to change back? Thanks for your response

 

[StevieC]

You will be ok but if you heater-core is partially plugged then you won't get much heat and could feel really cold.

 

[SteveSRT8]

Originally Posted By: renos09ram
Steve, I thought the 5.7 came with a 195 degree thermostat? So are you saying I will be fine by changing it to a 180 degree thermostat? What about winter time, will I be okay. or will I have to change back? Thanks for your response


Your truck should ship with a 203 thermostat. It is stock on almost anything they make anymore.

I recommend the Jet 180. It is a high quality (and a bit expensive) stainless unit which has a momentary spike to like 188-190 at first start up, then settles down to around 184-188 in average use. Works very well in summer or winter use.

Remember that if you do not reprogram the fans your truck will still run the stock temps in heavy traffic and high ambient. The only real benefit will be highway cruising.

 

[StevieC]

The trucks up here have 195's in them...

 

[renos09ram]

How do you reprogram the fans and what dergree should they be set at?

 

[SteveSRT8]

you'll need an aftermarket tuner. Diablosport is one of the best for Mopar.

get to their site at http://www.diablosport.com/ and read up in their forums to learn about the tunes.

What works on my car may not be applicable to your truck, as the control software is completely different in subtle ways.

If they support your truck you get control over a LOT of things and free internet updates