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 Technical Thoughts:
I'M NOT A SCIENTIST. I'M JUST A GUY WITH A MULITMETER AND AN IMAGINATION.


This experiment was set up to test whether or not insulating the walls of an enclosed cold air intake (CAI) would produce any benfits as opposed to leaving it uninsulated. This applies to cold air intakes such as the Helix, Alta, etc. where the open filter is protected from the engine compartment by sheet metal.

Setup

I used a Craftsman multimeter with a K-type thermoconductor. Updates roughly every .5 seconds. It was a partly cloudy night, 71F degrees outside and low-moderate humidity.



I wanted to test two areas of the filter and record the tempuratures while driving on the same path each time with the same conditions. The first location I wanted to test was on the wall of the CAI nearest to the engine. The second location was on the filter, nearest to the driver side cowel.

Location 1


Location 2


... and since the wire of the thermoconductor wasn't long enough, things got a little ghetto...

Test Day 1

I took a series of simliar road conditions and driving styles over set periods of time. Obviously they weren't exactly the same... but I wasn't planning on writing an entire scientific paper on this. These are just some numbers to think about.

I used my digital camera attached to the dash to record video of the numbers on the MM as I called out speeds. So that is how I got these numbers. Means and Stdevs were calculated from the End Temp. Statistical calculations do NOT include the idle start temp, that is just for reference. All temps are in F. Recorded times in relation to actual time, for the most part, are sequential.
Here are the raw numbers from the two runs.



The difference between a few inches of space in the CAI makes almost a 33degree difference in mean. However, the numbers are more all over the place with the on wall readings... more then double the stdev of the filter readings. I concluded that alone is proof that there would be a benefit of insulating the wall of the CAI.

The Insulating of the CAI

Using Duct insulation, I covered both the inside and outsite walls of my Helix CAI.
  

  

Test Day 2

Difference from day 1 was in the outside climate. Outside temperature was 80F and mid-high humidity. That means this test session was almost 9-11F degrees hotter. To counter for this change in the testing conditions, all of my numbers in the charts are based on the difference of the temperature inside the housing, and the temperature outside.

Here is the raw data.

Now this I found amazing!
More then HALF the standard deviation AND mean in the differences of internal to external temperature on the wall!

This should help understand visually.

From looking at this chart it is easy to see how the insulation prevents the side of the chamber from heating up as fast and as much when the car is at rest. But, as I expected, the difference in the two didn't matter as much at freeway speeds.

As expected, you don't really see a whole TON of change on the end of the filter, but that isn't really effected much by the wall of the CAI. Still nice to see a few degrees difference between the two tests.


Nice to know that insulating the walls makes a nice difference. Almost a 20 degree difference in the temp of air that the SC is getting when the air is drawn in from the side of the filter near the wall.

Take this all with a grain of salt. I think it would be a beneficial if you did this easy mod should you have a CAI. If you have any feedback of your own, don't hesitate to let me know about it: ben@shankrabbit.com



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