For years people have talked about how the WAI is at a disadvantage because it sucks in warm are from under the hood. However, I have never seen actual temp. readings. So, I decided to run a test.

Bought a car thermometer from Radio Shack, and installed the outside probe under the hood next to my Berk Intake. The cars outside temp. sensor is low to the ground in the front grill. Comparing the two readings, this is what I found driving around for 1 hr running errands: (List is in order form start to finish of my trip, and AC was on only in the middle of the trip)

....... .... Intake Temp.(F)......Outside Temp.(F)

In garage over night ... 79 ...75
Driving 50 MPH... ... ... 75 ...72
Stop at Light ... ... ... 78 ...72
Driving in Parking Lot... 83 ...73
Car off- sitting in lot 15min. 125 ..73
Driving again 45 MPH ... .. 85 ..75
At stop light ... ... ... ... 98 ..74
Car off in lot 10 min ... . 126 ...75
Driving 50 MPH ... ... ... 88 ...75
Driving 40 MPH ... ... ... 86 ..77
Sitting back in garage 30 min . 135...78


So, what I noticed is that when you are moving the temp is ok, running 3-10 above the outside. At a light it may go up 20 after driving for awhile, but comes down within 1-2 min once you get moving again.

Temps really go up quickly when car is off after driving, but come down within 3-5 min of driving again.

So what do you think? Are these temps what you would have expected under the hood?

 

What surprised me is the driving 40mph and up tempature. Going 45mph its still 85 degrees. When everyone swore that once your moving(driving) the intake temp should be close to outside temp......Well maybe not nevermind I guess 10 degrees difference is normal . But I wonder how much the difference is with the Cattman/PlaceRacing CAI....hmmmm.

 

I think it was showing 85 degrees at 45 mph since it was shortly after I had stopped at the mall and the underhood temp went up to 125

 

The problem with hot air intakes is that you'll get inconsistent performance at the track and boggy performance in around town driving because the hot engine air can't clear out quick enough therefore the motor is sucking in hot air. At the track can be especially bad because a 1/4 mile race only last 15 seconds or less therefore the intake temps won't drop in that short of a time frame.

As for CAI temps, my OBDII scanner indicates 1-2 temp difference from ambient during all driving, stop or go. Only when the car has been sitting for a few minutes does the intake warm up slightly (10-15 degrees). Once rolling the temp drops back to ambient. Driving around for an hour on a 85 degree day, the CAI intake pipe is still cool to the touch. It's pretty amazing.


Dave

 

You have too much time on your hands

Pretty cool experiment though

 

Thanks for doin an experiment I've wanted to do for years but never actually bought a thermometer. I'm still curious as to the temps of the air inside the intake piping close to the intake manifold tho with a CAI verses WAI or regular GAB. Maybe i'll eventually buy one of those thermometers and try runnin GAB and then my OSCAI setup

 

wow thats awsome that u did this! good info!

i never knew that it gets so warm after u shut the car off, but i guess it all makes sense

 

what i want to know is, would hood vents and those vented fenders that custom maxima offers the "Z3" ones or whatever, if that helps with engine temp and Cone/foam filter intakes etc.

 

It's always nice to see people taking some initiative...

 

I have mine set up with the stock airbox but no front scoop, and this past winter I was driving in ~40F weather with an Intake Air Temperature reading of ~70-80F consistently...

Typically after sitting around for a while the IAT does read ~130F. It is definitely hot in there.

 

nice lab work watson. But this whole WAI vs. CAI is really blown out of proportion. A ten (or 20 for that matter) degree difference in air temp. is not going to matter for the everyday, run-around-town, scope for boon Maxima driver. It might make a difference for a fully modded car built for 1/4 mile times, but humidity plays a significant part that often gets forgotten. For instance if I am out here in dry a$$ Northern Cali and you are down in humid a$$ Texas, my WAI will do just about what you PR CAI will do hp-wise. Check this out: assume for a moment that the outside air temp is 70F and the underhood air temp is 170F. Air density is related by the formula:

doa = square root[(460 + tuh)/(460 + toa)] x duha

where

doa = density outside air
duha = density underhood air
toa = temperature outside air
tua = temperature underhood air

therefore: doa = square root[(460 + 170)/(460 + 70)] x duha

doa = square root[ 1.19 ] x duha

doa = 1.09duha (well duh...sorry, couldn't resist)

( Note: the 460 in the equation allows the use of degrees F instead of having to convert everything to degrees Kelvin, absolute. )

So, outside air density is 109% of underhood air density, or 9% greater. Because mass air flow increases in direct proportion with density, HP produced with the cooler outside air will increase 9%. Therefore, an engine that produces 200HP with 170F air will produce 218HP with 70F air.

Useful rule-of-thumb: HP changes 1% for every 11 degrees F change in intake air temperature.

So we are talkin less than 2% hp difference, not a whole lot....

 

Wow, we have some smart people around here.

I found a nice article on intakes that is interesting to read (sorry, but its about the RSX)

http://www.ivtecdaily.com/rsx/modArticles.html

One interesting part is that they did real world underhood temp readings and found that during normal driving the air around the WAI stayed hot (110) even when the car was in motion.(see pg 3)

I have found with my I30 that the air around the intake is at most 10 degrees about outside air when in motion, and often only 3-4 degrees more. Today coming from work outside temp was 73 and I was running 76 at the intake.I guess we get better air flow under our hoods compared to the RSX.

As it gets hotter this summer I'll post some follow up temps. And I'll post some temps after a few interstate trips I have coming up. Just for fun.

 

Damn, he bust out an old school math book on ya. Hey whats the equation to find out the amount of mass in a box....I need it for a system set up.

 

I think Liqui has an excellent question there. I wonder is the scoops/vents would do anything significant to help lower the engine bay temp while driving.

Tony, correct me if I am wrong but you are looking for the amount of "volume" within a box not it's mass.

Now, volume = LxWxH however to calculate volume for various types of shapes go to : http://grapevine.abe.msstate.edu/~fto/tools/vol/

Mr.P