I have done some mods on my Insight, I started with placing six thermocouples in several places in engine, the first one is for outside air temp, second is for air intake temp, third is for coolant return to the engine, the fourth is for coolant coming out of engine, the fifth is for oil temp, the sixth is for exaust temp.
This is what I found so far, DO NOT block the radiator directly with cardboard, as temperature will rise to about 235 F with the outside temperature being around 60 F, the coolant return was about 217 F
air intake temp was about 75, the fan turned on but the temp will take a long time to go down. I immediately stopped the car, removed the cardboard and took off, in less than 1/4 of a mile the temp was back down to normal, Even at 235 F
, I didn't see the stock temp gauge climb significantly, it only moved about 2 bars.
What I found it works best to leave some space between the radiator and the cardboard, so here is what I did. I bought a bra for my car, I decided to modify it as well as make it more aerodynamic, I covered the lower air intake, and the results are as follows:
Outside temp 60 F. Incoming air temp 75 F, Coolant returning to the engine 140 F, Coolant from the engine to radiator, 190 F.
I have not done the Hot air intake mod yet, I will keep you posted what the temperature reading is, but I noticed that when you run the AC the intake temp. goes up about 20 - 25 F.
I took some pictures with the bra cover, I will try to post them soon.