NOTE: This is all with the factory temp gauge. I did not have logs to have actual temps.
This weekend I decided to seal off the heat exchangers to the mouth on my car. Hustler, while not being the only guy saying this, is by far the most vocal advocate. I already had the BEGI scooper on the bottom, their panel on top and an ABS shroud for the twin fans but that wasn't enough. I was running hot even on cooler track days. I did the BEGI rear exit reroute and that helped but didn't eliminate the problem.
I had a track day coming up on Monday with only two run groups, 1/2 hour sessions and temps expected in the high 90's. I went to work doing a cheap and fast job sealing up the heat exchangers better. I bought a little sheet of galvanized steel and another of fairly thin and flexible plastic. About $20 total. I already had a roll of heat shield padding laying around. This has a shiny surface over what looks like wool carpet pad.
I cut some of the heat pad to fit under the aluminum BEGI shield. This I expect seals the air off better than metal on metal and also keeps that shield from rattling.
I then cut some strips of that padding, rolled it up and crammed it down beside the radiator to seal off the sides of it.
I took the tin and cut it the width of the opening of the BEGI scooper and cut the front the roundness of the stock spoiler. Using a 2x4 and the floor I bent it into a curve. I took the leading rounded edge and tweaked the front lip up slightly so it curled up into the spoiler. Drilled a couple holes in it and the scooper and zip tied it into place. This gives a nice curved surface for air to cling to from the bottom of the spoiler into the scooper.
Also with the BEGI scooper the tabs on the stock portion of the opening are left loose. I zip tied these down to the scooper also. This opened up the mouth about 1/2" and gave a more rounded surface.
I cut the flexible plastic sheet to seal the sides from the scooper to the mouth of the car. I cut slots and holes to get around the IC pipes. These I zip tied and used home depot outdoor foil tape to seal off and hold in place. That flexible plastic lets you pull it tight to odd shaped parts and cram it into places you can't with tin. Makes for a quick easy seal vs. doing the job of removing the front and building a proper air box.
Used the outdoor foil tape to seal the scooper to the radiator better and also the plastic sheets.
cut slots in the plastic and zip tied to pull snug around the IC pipes.
Not all that pretty but everything is out of sight unless you get under the car to look. Proof was in the pudding. 98 degrees, 7 30 minute run sessions. The factory temp gauge never even wiggled. There were even times coming in from the cool down lap it read slightly low. This is all without any kind of undertray so pressure differentials aren't ideal. I've now been driving in 104 degree weather in stop and go freeway traffic with my AC on. Still no issues.
Thank you Hustler! Your advocating sealing the exchangers is the right advice for temp issues. It's the first thing I would do rather than the last if I had it all to do over again. A couple hours work and maybe $50 spent on materials.