Okay, there has been a lot of typing going on about Cold Air Intakes (CIA), our poor stock intakes, how cold air is so much better for our trucks, etc. I have done some testing to measure outside air temperature vs. air temp at the inlet to the intake and the temperature inside the filter box. So I started this thread to discuss air temperature.

I was motivated by this statement
and decided to do some testing.

My truck is a 1999 Ram 1500 with 5.9L motor and a stock intake.

I used two indoor/outdoor thermometers, one with a wireless remote, the other with a sensor attached to the wire. I removed the tube from the fender to the air filter box and secured the wireless sensor to the inside of fender, in front of where the tube picks up the air. I fastened the receiver to my driver's side mirror. This thermometer displays both the outside air and inside air temperature on the screen. So this thermometer is giving me the outside air temp and the temp of the air leading to the air filter. I placed the sensor for the other thermometer inside of the air box, on the intake side of the filter. I taped it so that the sensor is sticking up in the air and is not touching the filter or the air filter box. It is in the center of the box. The receiver is placed inside the cab on the dash.

I drove to work this morning which is a 14 mile trip over back roads, mostly 40 mph with one 3 mile stretch at 55 mpg. The last two miles is in town with speed averaging 20 mph. The outside air temperature at home was 25 F. As I drove to work it crept up to 31 F.

So, I pose the following questions. When traveling down the road, how much higher is the air temp at the intake? Inside the filter box? What if I moved the location of the intake, would the air temp go down? What affect does being stopped at a red light have on the temperatures? How high does the temperature go after shutting off the truck?

I know and I will post my results later today. They are interesting but not surprising if you actually think about it.

Over the next several days, I will move the positions of the sensors to various locations, such as to the right front corner where the K&N and other CIAs pick up the air, to the right rear of the engine compartment, and immediately above the air filter box for those of you running open round air filters. I also want to take off the tube from the fender and measure the air temp inside the air box. Let me know if you are interested in the results.

 

yes, interested in the results, you should also add in the data from the IAT sensor if you can collect it. A friend of mine has a Car Chip that collects whatever parameter you program it to. I looked at the IAT sensor and what I found was after about 5 minutes of driving, everything looses it's heat soak and the intake temps stabalize. I dont remember at what temp it was... :-( I still have the data at home (I think...[&:] )

one thing you dont have in your comments is how your going to simulate the heat shield for the K&N setup... any idea? One could be to go to Wally mart and get some poster board and make a shield that's close to the K&N's. I did this with a BMW 325 I had a couple of years back and it worked great until I was able to get my real shield delivered. One interesting note regarding the 325 stuff was that when the shield was gone, I lost power... low end & top end from the heat I was sucking in. JUST by adding a $1.00 piece of cardbord between the motor & the filter was night and day in the power.

Looking forward to your data...

 

Here is the data, it took me a little while to get it into a table format. Some notes, the mountain that I talk about is a 440 ft. climb over a distance of 0.8 mile, which is about 9% grade. I drove up it at 45 mph with O/D locked out. I don't get over 2500 rpm when I drive, so no quick starts or hammering the throttle. The thermometer has a max/min function, so I was able to check how high the temp got after the truck was shut off, but I don't know when it occurred.

Time/Dist……Outside(F)…...Intake(F)……..Filter Box(F)………….…Notes
Start…………………25……………..…25 …………..…….27.1
1 min………………. 25………………...25………………..26.4
4.7 mile…………….30………………..27.5…⠀¦â€¦â€¦....31
6.4 mile…………….28…………………28…†¦â€¦â€¦â€¦â€¦..33.6……..Top of mountain
…………………………………………†¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦.........39………Highest temp after mountain, coasting down other side
8.5 mile.............29................29............. ...37.6
10 mile..............29................28............ ....38.7
.................................................. ...........42.........Highest temp @ 55mph
14 mi.................31...............31............ ....47..........In town, 20 mph
After this point, stopped in parking lot and let truck idle
30 sec............................................... ......59.5
1 min............................................... ........62.6
1.5 min............................................... .....66.6
2 min...............31.2..............35.5.......... ....70.2
2.5 min............31.2..............37.8............. .74.8
4 min...............31.2..............40.3.......... ....82.9
At 4 min. I revved truck to 1500 – 2000 rpm for about a minute, filter box temp continued to climb.
Shut truck off and checked data later.
25 min...................................46.......... ......112
?................................................. .............115............Max temp recorded
2.5 hrs..............43.................45............ .....49

 

you can see the filter getting heat soaked when it's idling... dropping power of course. It would be interesting to see the same data compared against the k&N kit...

 

I thought about this, but I don't have my own equipment to do the testing. I have a friend who has a Snap-On scan tool that could probably check the IAT, but I would have to get together with him to run the test. It would be interesting to see how much warmer the air gets as it is entering the intake.

I currently have the factory fiber shield between the radiator and the frame. I am debating whether I want to remove it for the test or just put the sending unit right in front of this shield. If I remove the factory shield, I can do two tests, one with a mocked-up piece of cardboard or styrofoam, and another test without the shield in place to see how much heat is in that area from the engine.

I first ran this test on my Spirit. It has a single port throttle body with a heated air intake. A temperature sensor in the air filter box is supposed to control a valve on the intake that allows either heated air, a mix, or cold air only to enter the box. The cold air was pulled in from behind the headlight. That was an interesting test because I discovered that the temperature sensor was bad and I was only getting heated air into the air filter box. When the outside air was 35 F the temp inside the air filter box reached 135 F. I bypassed the temp sensor so only cold air was being pulled in and had similiar results to what I showed above with my truck. The filter air temp ran about 10 F - 20 F higher than the outside air. When I stopped or was moving slowly, the filter air temp would go up about 40 F higher than the outside air, but as soon as I started again, it dropped quickly.

One difference with my car is that it has a metal air filter box, sitting over the top of the engine. I recorded temperatures of 150 F after the engine was shut off. So I believe the metal conducts much more heat into the box.

 

If someone is willing to send me one I'll run the test report the data back to you. I'm looking for sponsorships to keep this going. Maybe even some coated headers to see if they help reduce heat, Hypertech tuner, a good looking blond to record the temperatures while I'm driving down the road.

Seriously though, the nice thing about the stock setup is that I can put the sensor right in front of the air filter and I don't have to worry about anything getting sucked into the motor. I would want to make sure the sensor is well secured if it is put inside the tube of your K&N tube, after the filter.

 

order one, do your test, then send it back

 

I drove home from work yesterday going a differnet route since I had to stop at the store. Here is the data:

Time/Dist……Outside(F)…...Intake(F)……..Filter Box(F)………….…Notes
Start…………………44……………..…37 .7…………..…….39.6.....Outside temp higher due to thermometer being in sun
1 min………………. 44………………...37.1………………..38. 7....Idling
1.5 mile…………….37.8……………….37.6… ………......37.2
2 mile...…………….36.2………………36.5â €¦â€¦â€¦â€¦â€¦â€¦â€¦36.2
7.7 mile………………36…………………35.5â €¦â€¦â€¦â€¦â€¦â€¦..43……Stopped at store, < 10 min.
Start................37................35.5....... .......69.4
1 minute............?....................?.......... ......65.3.....Driving thru town, 20 mph, from Start to 3.5 minutes
1.5 minute..........?....................?............ ....60.....? - Couldn't write temp while driving
2.5 minute..........?....................?............ ....53.8
3.5 minute, also 8.8 mile.............?................50
19 mile...............33..................35.6....... .....44

After leaving the store, I stomped on it a few times for a short distance, (you can't get up much speed on these back roads,) and the temperature started decreasing. So you can see, with the temperature in the mid 30's, the stock air setup is going to run about 10 degrees higher than outside air due to heat generated from the engine. The air entering the stock intake is the same temperature at the outside air. Insulation around the air filter box may help reduce the temperatures.

 

Varied the experiment this morning. I pulled the tube off connecting the air filter box to the fender. Moved the sensor that was inside the fender well and hooked it up to the transmission dipstick so it was sitting right in front of the inlet to the air filter box. Took a trip into town for parts, about 4 miles. Truck sat for 10 - 15 minutes, then drove home taking an extended drive. Total distance from home to town and back again was 13 miles. Outside air temperature was 35 degrees. Highest recorded temperature of air at intake inlet was 65 F. BUT, air temperature inside filter box ranged from 70 F to 80 F, and stayed near 80 F after the truck was fully warmed up, near the end of the trip. Stomped it a few times but never got the temp to go below 75 F. I was suprised how much warmer the air was when pulling it from this location. I want to try making a modified inlet so I am pulling the air from different locations, as noted in the first post.

 

I ran the test again without the tube from the air filter box to the fender and drove to work, so you can see how temps compare to the first test.

Time/Dist……Outside(F)…...Intake(F)……..Filter Box(F)………….…Notes
Start…………………17……………..…13 …………..…….15.8.......2 min. warmup, no change
0.5 mile…………...18.2…………...15.5……†¦â€¦â€¦â€¦..19.2
2.4 mile…………….15.8………………15.1…⠀¦â€¦â€¦....17.8
4.7 mile…………….17.8……………….17.7… ………....22.1
6.4 mile…………….17.8…………………25… ……………..69……..Top of mountain
8.5 mile.............16................33.3........... ...57.2
10 mile..............17................38............ ....60
.................................................. ............65.........Highest temp @ 45mph
14 mi.................18...............44............ ....77..........In town, 20 mph
30 Min.……………...19………………..76…⠀¦â€¦â€¦.....117.......30 Minutes after shutdown

Note that although outside air was about 10 F cooler, temp in the filter box was about 20 degrees warmer when traveling down the highway with this test. I feel this is the best I can do to simulate a circular, open air filter. I did get some tubing and hope to simulate the K&N style inake within the next couple of days. I'm just using corrugated plastic tubing to attach to my air filter box, but hopefully it will be a good comparison. Added a photo gallery showing how I set up the thermometers and sensors. Click on the icon of the camera to the right.