How was the fuel economy on that trip? Factory spec is around 15 Litres per 100Km.

 

Did 516 Km with one full gas tank

 

Not sure what you're accomplishing here. Once you hit 180*F(82*C), the thermostat is fully open; it doesn't change how hot/cool your truck will run after that point, and your truck WON'T stay at 180*F. Mine already runs between 195*F(90*C) and 205*F(96*C),...with the stock thermostat, in SoCal heat and traffic.

 

Me thinks he had old coolant, bad thermostat prior to his swap.
I keep trying to explain to him that without adjusting the parameters of the ECM, the ECM will keep changing the timing, add more fuel, etc. to reach the optimum operating temperature set by the manufacturer.

 

Good to know, thanks for info

 

I understood that, thanks. My coolant was 1 year old and my thermostat was an aftermarket one. The OEM thermst gives live up a few years ago.

 

Guys the computer doesn't do anything to try to achieve a certain temperature. It goes closed loop for emissions purposes at about 175-180 degrees, that's all. As long as you're achieving closed loop, everything will be fine.

True, higher temps are generally better for emissions reduction, but lower temp will reduce preignition tendencies, which is helpful when running a tune. Factory tune is fine with 195 degree stat.

If you have a stat fully open at 180 and your engine routinely exceeds190, your cooling system simply isn't up to the task.

 

In the fbody ls1s, their cooling system is sufficient enough that they can program their fans to drop the coolant temps below the oem tstat value, so they swap to a lower tstat.
With the H3 its not the case. The radiator is barely adequate for an I5 so unless you upgrade the clutch fan and radiator, or run in a cool climate, you wont drop the coolant temp any further than what it currently runs at. You will just make it get their slower initially but aftwrwards it will be similar to a stock tstat.
As for power numbers, i didnt take a good look at the I5 timing tabled, but if GM treats it like the LS engines, they retard timing above 200*. So running lower wont net you any more power unless you change the timing tables (add timing) so the lower temp area. You will need to get it professionally tuned to address that.

 

Thanks guys for all those infos. Well my rig is running and cooling excellent, no issues. I just let it like that, as long it runs so fine.

 

In hot summer gridlocks there may be advantage to running cooler thermostat.