Re: Open Element Air Cleaners: Some temperature measurements

From: Mike Catlin (
Date: Mon Jun 22 1998 - 11:39:25 EDT

>Scott Wrote:
> This weekend I picked-up a very cool gadget from a local Radio
> Shack. The Shack sells an "Auto/RV Thermometer" for $15. It
> is about the size of a pack of gum and comes with a 6-foot
> lead and termperature sensor.
> The temp is displayed on an LCD display down to the tenth
> of a degree. I mounted the thermometer on my driver side mirror
> with the included adhesive (put her right on the glass, next to the
> top of the mirror housing). I then snaked the temperature lead
> under the hood and into my Mopar Performance open element
> air cleaner.
> Here is what I found:
> Driving down the Interstate tonight, I found that when I was
> cruising at 65 mph, the temperature of the air going into
> the throttle body is 35 to 40 degrees HOTTER than the
> ambient air measured at the mirror. Yes, cruising down the highway
> gives a difference of 35 to 40 degress. The temp outside tonight
> varied from 72 to 75 degrees as I cruised along the Interstate.
> The temps in the air cleaner were around 110 to 115 F. <==< =:^0
> When I got into town and went from stoplight to stoplight, it
> got even worse. I was seeing air cleaner temps around 120F. <==<
> YIKES!!!!!
> These open element air cleaners are sucking tons of hot air from
> under the hood.
> I did notice once neat thing: I started the truck after it sat for a
> while and drove off at a reasonable pace. The temp in the air
> cleaner wasn't that much higher than outside air. I then
> watched the coolant temp guage on the dash climb to
> operating temp. Boom!!! The air cleaner temp started to climb
> rapidly. It's not the engine block giving off all that heat, it's
> the hot air coming from the radiator. We're sucking
> in air that has been heated by the radiator. Ugh!
> I even tested cruising as fast as 80mph on the Interstate. This
> doesn't help the air temps in the air cleaner. In fact, it hurts.
> At higher speeds, the temp is guaranteed to hang around 120F
> when the outside temp is in the low 70s.
> I challenge all Dak owners with to purchase the same "Auto/RV"
> thermometer from a local Radio Shack and report their results.
> Mount that baby on your mirror and guide the "measuring part"
> under your hood. Post the results.
> My next test will be to local the "measuring part" near where the
> factory air box got its fresh air supply (near the front,
> passenger-side corner of the engine compartment) before I removed it.
> I am very suprised at these numbers. Especially at high speeds. I
> think we're going to have to scrap the open element air cleaners.
> Raising the air temp by 40 degrees *can't* be helping our
> performance.
> - -Scott
> p.s. If you kick on the A/C, that's good for another 8 degrees of
> heat going into your open element A/C. Sigh... :^(

        I found the same thing when I did that. My reading was
110 degrees for the open element and 89 degrees for my ram air.
Don't scrap your open air. This weekend I hooked up my ram air
to my open air element. Runs great but no track measurements yet.
All I did was bought a 8' pc of aluminum dryer vent hose the kind
that you can expand to 8' even though when you buy it it's only
4' long. It's aluminum not vinyl. Anyway stretched it out to
8' then cut a 2.5" slot in about 5-6' of it. I then took it
and wrapped the slotted portion around the air cleaner making a
complete circle with the non slotted end ducting down to my old
ram air connection to the left of the radiator right through
the rubber splash boot. So far works great sucking cold air.
The aluminum dryer vent is stiff so you can bend it pretty tight
around the air filter (I have the MP performance air cleaner, lid
measures 13.25") although if you have a true 14" air filter it
probably won't work due to fire wall clearance. I'll try to post
some pics in the next couple of days.

Mike Catlin

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