KingBird wrote:I don't really want to rain on anyone's parade here but the stock radiator can MORE than handle the loads we put on these engines.
A couple years back, when I replaced my engine, I ended up installing it the way it came and it apparently had a failing thermostat.
While heading up into the mountains for a weekend trip, my alarm on torque started going off and I was at 235 degrees. I parked it immediately and simply waited. I walked down to the gas station and bought a couple gallons of water, then added one of them to my overflow tank. I was only a few miles from the house up there, so I limped it there.
The next morning, I diagnosed that it was the thermostat and since I had no other vehicle handy, I simply removed it and put everything back together. I went and got a new one but the engine barely topped 100 degrees. So, on the way back, I tried to get it up to operating temperature. I was worried about doing so since the coolant was mostly water, but I had some spare full jugs just in case I started boiling over.
I drove it HARD. It was never below 3000 RPM, I had to stay below 30 as well so I kept it in low, and the temp barely climbed. I decided to head up to the point, a relatively gradual climb but a climb up to 10k ft nonetheless.
I saw my greatest temp change at about 8k, but it never topped 160 degrees no matter what I did and even then, once it returned to a lower RPM, the temp plummeted.
I never got it to operating temperature, and I felt guilty for driving it that way with the new motor.
Once I was back home here on the plains, I did some experimenting and found that if you modify the ring on your failed thermostat by cutting a wide pie slice out of it on one side, the engine would get to 200 degrees eventually. Two pie slices cut directly across from each other yields 160 degrees and lower with normal driving, of course.
The restriction is the thermostat, just like usual, so if you're having issues cooling, I suggest a lower calibrated thermostat, if available.
Water at 15psi boils at 250F, so normal engine temps aren't a problem for just water. However, water also has right at twice the thermal capacity of straight coolant, and 50/50 mix has about 3/4 the thermal capacity of just water. So yes, on a clean radiator (no mud dried into the fins, reducing the transfer properties), filled with mostly or all water, you'll have like double the cooling capacity of a 50/50 setup on a dirty rad, and you'll have 25% more cooling capacity than a similarly clean rad with 50/50 in it.
Also, the higher RPM aides in cooling, because it flows a lot more coolant than 1700-1800rpm at cruise. Hell, with the A/C on, on like an 80 degree day, I run 205F in OD on the interstate and 195 in 3rd (That's with having driven through a lot of hood-deep muddy water since I've sprayed out my rad, which I need to do). It's all about the amount of heat/load that's put into the coolant in the time it goes through the engine, especially on a non-working thermostat.
Mike