GordnadoCRD wrote:
Since we're not in a place to make our own heads (at least I'm not) out of a better material, the only things we can do to decrease this thermal current gradient is tune them back to the original F37 OEM tune, OR, increase the operating coolant temperature, which brings a mixed bag of tricks, and while it will decease the thermal gradient, I have no idea how much is necessary / enough.
Are you saying that the operating temperature of the engine should be increased?
To me, is seems that the operating temperature should be decreased. But I guess that depends on a variety of factors. If the operating conditions dictate the engine to run at 220F, it will do so, regardless of the operating temperature of the thermostat.
Or are you saying that the coolant/water ratio should be changed?
Or at least carefully monitor coolant ratio and condition?
Straight water has a greater heat capacity than coolant. But coolant has a higher boiling point.
I would never recommend running straight water (corrosion). Best to mix in some ratio like 50/50 or 60/40 (water/coolant).
It seems to me that coolant flow, or lack there of, is the main problem (i.e. inline thermostat).
After replacing my cracked head I had a theory that maybe the rearmost cylinders were running hotter than the front. So I stuck a temperature sensor on the side of the head between cylinders 3 and 4. Its not really the best sensor. Its not actually inside the head. Just stuck to the side. But it gives me some interesting data.
1. once everything is fully warmed up and I'm cruising at highway speeds, the cylinder head temperature is consistently ~20F cooler than what the coolant temp sensor is reporting.
2. when I slow down and have to stop at a light, cylinder head temp starts to increase. If I'm stopped long enough, cylinder head temp will eventually match the coolant temp.
This tells me that when then engine is operating at a higher rpm and there is good airflow through the radiator, the coolant is doing its job by pulling heat away from the head. Mainly due to increased coolant flow. (hey, its the best I've got to go with. Feel free to scrutinize those details however you wish)
Lastly, the symptoms of the cracked head were present before I did any kind of ECM tuning. Just using a stock tune. Although I was ignorant to those symptoms at the time.