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

[delusionz]

in the stock setup theres a temp sensor in the air box and a temp sensor in the manifold. most likely the stock ecu uses both

my powerfc plug-in ecu however only has correction table for the manifold temp sensor, the one in the air filter is just for datalogging

manifold is where it needs to be



and yes, everything on the st205 bonnet is functional and all from rally. the little nostril thing is the cambelt cooler, apparently the st165 rally car snapped cambelts from excess heat, hence it first appeared on the ST185RC

[match220]

in the stock setup theres a temp sensor in the air box and a temp sensor in the manifold. most likely the stock ecu uses both

my powerfc plug-in ecu however only has correction table for the manifold temp sensor, the one in the air filter is just for datalogging

manifold is where it needs to be

I don't think I have the expertise that would trump a team of technicians that have decided to put the air temp sensor in the manifold, that is my disclaimer before I say everything I am about to say. Maybe they can get away with one AIT on the mani since there is a second AIT elsewhere. They could perform a calculation similar to... [airbox AIT + mani AIT / 2 = x]..or instead of averaging the two sensors they may have a percentage of [x] that is used depending on the runtime, RPM, MAP, etc. The ST205 stock ecu may have a separate table specifically for the two sensors and how fuel mixtures are calculated with those two depending on the RPM, MAP, etc., during testing I would imaging that they placed other air temp sensors throughout the systems and deduced that (if airbox AIT is at this temp, mani AIT is at this temp, and RPM or turbospool is at _____, then they can fill out a range of average temps under those conditions. There are a whole range of calculations that can be done with a car that has two sensors under completely different temps and pressures, especially when calculating that info with other sensors. From what I've seen on the GenIII setup, it isn't in the airflow stream on the manifold, it sits off to the side of the airflow. I would think it is more susceptible to heat soak there. With that in mind I would say that the manifold alone (without the airbox AIT) is not the best place for the sensor unless you can add a second sensor and mimic whatever calculation they have that averages the two sensors. It is for that reason that I didn't put it in my manifold and instead chose to put it in the intake tubing. My Autronic doesn't accept two AIT sensors either, so I have selected the best possible place to mount the AIT. Which is not directly above the engine, but as close to the TB inlet that I can get it. I may move it closer to the fender about a foot away from the I/C as someone mentioned above, but that will come when I decide to pay an aluminum welder again and buy another bung to go in my tubing.