Although we were not able to track down the actual appropriate type of pushpin from Cadillac, I was able to buy a variety of pushpins from various auto supply stores and find a set that have the offending radiator deflector pinned once again against the bottom of the radiator and intercooler heat exchanger. So now all air flow through the front grills is directed to cooling.
Next I ran up and down the highway to see what impact this had on my IAT2 temps. It is a warmer day, and the STS-V is heat soaked. Here is a representative snap for today:
Ambient is around 82F, Intake air IAT1 86F, which is good, and IAT2 is hovering at 120F steady state. This is the expected +30F or so from IAT1 to IAT2 that I would like to reduce.
Today’s trial of ensuring the ducting gaps around the front mounted heat exchanger (FMHE) for the intercooler are closed showed little impact on IAT2. I am glad that I have this fixed but I didn’t see a major change in IAT2.
During the drive I did try running the STS-V in 4th or 3rd to raise the revs, which caused an increase in IAT2 as more air flowed through the supercharger. When I went back to 6th the IAT2 returned to status quo.
For the next trial, after 23 minutes into the test drive, I stopped and let the car idle while I sprayed cool water over the front mounted heat exchanger.
I then drove at 20-45 mph and monitored the impact on IAT2. This had no or limited effect on IAT2.
After 35 minutes into the test drive I stopped again and used a leaf blower to direct air into the front mounted heat exchanger to simulate a fan on the heat exchanger. IAT1 rose to 147F at idle, due to the lack of cooling air flow into the system, and IAT2 stayed at 135F. I conclude that this had limited effect on IAT2.
Intuitively, both a water spray on the heat exchanger and a fan on the heat exchanger should have led to more efficient cooling, and thus lower IAT2s. There appear to be factors I am not accounting for in my experiment. I am not measuring the water temperature in the FMHE itself, but rather the resulting IAT2 which is the temperature in the manifold downstream of the supercharger and intercooler. If the heat load from the intercooler is beyond the capacity of the FMHE, even with help such as the spray or fanned air, it would continue to overwhelm the FMHE and maintain high IAT2 regardless of adders or not? Thus the conclusion that most modders reach is to supplement the FMHE with a 2nd FMHE and / or replacement for the OEM FMHE.