what are your air intake temps? Options

[match220]

Hey guys,
Since I have a Gen III in my st204 w/o a GTFour body kit I've been watching my intake temps carefully. (Autronic brand IAT is mounted as close to the engine as I can get it without it being directly above the engine). When I first finished building the engine for the car I still had the insulation on the hood and had a semi covered enclosure for the air filter. The hottest my air intake would get was 80C (crazy!) and that was sitting in traffic with no airflow over my I/C (front mount). Then driving it was around 65C. At night driving it would go down to 60C.

After pondering what to do and talking with some drifting friends, I ended up raising up the rear of my hood 4mm, which isn't even noticeable, removing the weather stripping. And also removing the insulation from the hood and making a full enclosure around the airfilter out of plastic and Plexiglas . NOW my air temps are 60C on a hot day sitting in traffic with no air flow over the I/C, and 45C moving on the freeway on a hot day. At night on the freeway it is 40C.

relevant intake info(shortened from above): big fmic (air/air), and Autronic brand IAT mounted two feet from TB inlet, not directly above engine. Numbers below are before and after a full air filter enclosure and raised rear of hood 4mm.

-------------------------Before-------After
hot day in traffic------80C---------60C
hot day on hwy-------65C---------45C
night on hwy----------60C---------40C

(80c is 176f, 65c is 149f, 60c is 140f, 45c is 113f, 40c is 104f)

So now that I've mentioned my numbers, I would like to know what your numbers are. I'm expecting it to be cooler once I get the hood vents. I would like to know what the norm is for this engine. Also please mention if you have the fmic or tmic

This post has been edited by match220: Aug 3, 2013 - 5:13 PM

[lagos]

Some people also recommend to actually mount the IAT in the fender, away from the engine bay.
The theory behind this is that inside of the engine bay the sensor is going to get heat soaked and actually read higher than the air flowing through it.

I actually had to fudge my MAT correction table to get mine to display correct a/f ratios in hot weather, due to the temp sensor getting hotter than the air flowing through it.

yeah, I've been trying to avoid heatsoak the best I can while still mounting it close to the inlet. It would definitely throw off calculations and a/f ratio a bit. I would have to have another bung welded on just to experiment. Or I could wrap that section in heatwrap for an ugly solution

You can also fudge the idea gas law curve in your mat temp corrections table. Thats kind of how I did it.
The best way to know if you need to do that is to shut the car off after you were driving, let it sit for 5min so that the mat temp goes up as high as possible, and the restart the car. If your a/f ratio goes really lean right after the restart, then the sensor is heatsoaked and not sending the correct air flow temperature. If thats the case, you'll have to fudge your temp curve.