OKeeeeee...So I've been hit by the nasty overheating with the A/C on bug and have a question: Who here knows the actual math for figuring out the max amount of heat that can be sunk through the radiator? I'm curious what happened to me yesterday,

I have my air dam and all the plastic radiator shroud pieces. I can be cruising down the turnpike @ 100MPH for 15 minutes at a time and the temp is stuck right at 180*. If I'm in stop-and-go traffic with the fan running constantly, I stay right at 180*. With the A/C on, I normally run 180* on the highway & 200* in stop & go traffic. Yesterday, I was cruising around at about 40 MPH with the A/C on and noticed that I was hovering arounf 235*. Kinda freaked me out. My ride never gets that hot unless something is wrong (when I got it, the car had no air dam & this was common). I thought I was a bit low on coolant because I lose maybe 2 cups of fluid a month, but it was perfect when I checked. The ambient conditions were kinda hot: ~60% humidity & 95*, but the car has never acted this way since I fixed the cooling problems.

I'd like to know the math so I can figure out the max temp/humidity that my car is capable of running at and along the way this will prove/disprove if I really have a cooling problem.

Last week, I bought a 180* Stant (P/N 13358) thermostat which I plan on drilling four 1/8" holes through, but haven't installed it yet. This is merely to allow for more spark timing in the future, but if I'm running this hot now, I don't want to run more timing. My car already acts strange if I let it go above 200* (i.e.: stop-and-go traffic without my manual fan switch on). The car will out of nowhere pull a LOAD of timing and then throw a code 43 -- with the stock chip. I feel it lose maybe 50 HP and about 5-10 seconds later I get the SES light. If I don't let the car get over 200*, I'm fine.

 

Tell me the water velocity your pump puts out, the exact running presure of your cooling system, and the exact ratio of antifreeze to water, as well as the fins per inch, and the size of your radiator to get a rough estimate on it's surface area.

Oh yea, you're thinking too hard. In the time it takes for you to figure out the exact thermal dynamics of your cooling system, I can flip your question around and re-ask you:
If you're so concerned about going over 200°, why don't you go after the problems of such, rather than trying to use some complex math to find out that "hey, it's Thursday, too hot to drive my car."

K.I.S.S. (i.e. it's a SYSTEM, make sure it's working as such first.)

 

Well...I really just would like to do that math just to have done it. I understand the GM engineers went through all this years ago, I'm just curious. As for the hot engine temps: I can keep it between 180* & 200* all day long no matter where I am. I was just worried about the high temps I saw on one particular day. The next day was just as hot and the temps were normal (~180*).

The detonation circuit has been partly addressed; I just haven't had the chance to really work on it yet. I replaced the knock sensor and ran a secondary ground from the ESC module just as a test.