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"TKG 26" PM'd me to ask what my thought were on insulating this tube to protect it from engine bay heat. This got me thinking and I just had to go out and do it.
I've had my AEM for a few months now and it has proven really effective by the "butt-o-meter". Now I will start to take some temp readings to see if there is a correlation. I used the word "measurements" rather than "recordings" as I did in my last experiment because most people really didn't much care about actual numbers, just what the results and observations were.
The first bunch of runs will be with the tube insulated with the same stuff the "radmat" is made of. "Bare naked" AEM tube runs will follow once I'm satisfied that my observations are consistent. Here are some pics: This is the device I used. This shows the stick the probe was taped to so it would not touch the sides of the tube and where the probe was inserted into the same opening that the air pump hose attached to. The probe pretty much sat in mid-airstream. The fugly tube wrap.
Observations from my first run:
Sunny day, winds light, ambient temp at "traffic level" 22-26*C. I say "traffic level" because this is usually hotter than what the weatherman tells you due to heat from traffic and reflected heat off the pavement. Speeds varied from 50-80 kph (30-50 mph).
From a cold start and until a few minutes after 3 bars on the temp gauge, the intake temp ("IT" from now on) was 1-2*C BELOW ambient. How's that possible you may ask? We know that in FI, the intake air gets heated from compression (that's why an intercooler helps). The opposite is true. Air flowing at speed through a tube produces a lowered pressure (Bournoulli's Principle) and thus a drop in temp.
Obviously during this time, the engine bay has not gotten hot yet.
At my first red light, IT rose to about 1-2* ABOVE ambient. Once under way, IT dropped back down to about ambient within 15 sec. Another 1/2 minute and it was back to 1-2* below.
After some driving later, I went into a store for about 5 minutes. Upon return the probe read almost 50*C. Once under way, the temp dropped back to 1-2* above ambient within about 30 sec. Another 30 sec, IT was at ambient.
Then came a series of red lights one after the other. After each light, IT rose to about 5-6* above ambient but again, once under way, dropped back to 1-2* above ambient by the next light. If I sat at the red light and kept the revs up to 2000-2500 rpm, IT never rose to more than 1-2* above ambient.
On one occasion after a red light, I VTEC'd away (not WOT) and the temp was back to about ambient by the time I shifted to second.
I make no conclusions at this time (you can if you wish). More insulated runs to follow.
You may have seen this on some other threads pertaining to the AEM, but I figured I would post them again. This insulation tubing is made specifically for insulating intakes. It may look like an every day clothes dryer tube, but it has a thin fibrous insulation layer under the reflective surface. One advantage that I think this has is that it is slightly larger than the pipe, so there is very little contact between the inner and outer tubes. The air space between the two tubes acts as additional insulation. If I can get ahold of a decent thermometer like yours, I will take some measurements too.
*praying to his/her holiness* "please let vipe's IT's be higher during the un-insulated runs" *ok, back on my feet*
if the IT's are higher when un-insualted, obviously there is a benefit to wrapping the CAI - right??
or would the "value" of the variance be the factor??
i.e. 2 degrees higher = big deal, 20 degrees higher = someone call MIT, we may be on to something ........
or, there may be no difference as any given "block" of air travels through the system too fast for it to be affected by heat?? i.e. the amount of time for the air to travel from beginning of CAI to end of CAI is very tiny or negligible (1 sec, 5, sec, ?)
gernby, your insulation looks one heck of a lot nicer than mine. As for insulation characteristics, the stuff I use also has air space in between in the form of "bubble wrap" material. You can get a thermometer at any autoparts store. These are the ones that are the indoor/outdoor types and some may even have a clock in them. They are not scientific but I have calibrated mine with a laboratory mercury thermometer to ensure accuracy through the temp range that I'm dealing with. The only setback is that they may not measure "change" temp fast enough to show what's really is happening. The fast change thermisters simply are too expensive (hundreds of $$) for the "hobbyist" use.
I definitely think that your insulation is going to do its job better than mine, but I am interested in seeing how much of a difference there would be. It may be the difference of 1 degree F. I think the benefit of mine is that it does look better, and it was a snap to install.
I do have a couple of thermometers that have indoor sensors, and an outdoor sensor on a long wire. I guess I will use one of them, but I have always doubted their accuracy and response time.
[QUOTE]Originally posted by gernby
[B]I definitely think that your insulation is going to do its job better than mine, but I am interested in seeing how much of a difference there would be.
Do you have your fake brake duct cut out where your AEM filter is located? I have mine completely open, without a screen. I'm wondering if I am getting enough of a "ram air" effect to pressurize the pipe, causing the temperature to be a little higher.
Anybody have any ideas on measuring the pressure / vaccuum in front of the throttle body at speed?
08-07-2002, 01:19 PM
AEM CAI temp measurements.
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