I've been curious for a long time whether a real CAI actually makes a difference in air temperature delivered to the intake manifold. So last night I rigged up my indoor/outdoor electronic thermometer to find out.

First off, I have a stock airbox, stock air filter with resonator assembly removed.

I put the thermometer sensor in the rubber connecting tube (flex tube) at a location about 1 inch prior to entering the metal intake manifold. Rubber is a good insulator, so it is resistant to heat conduction from the metal manifold into the rubber flex tube. I assumed that this would allow me to make the assumption that the temperature given by the sensor would be the actual, or close to actual temperature of the air passing through the flex tubing.

When I hooked this up last night, my car had been sitting for abotu 30 minutes after my drive home from work. Within 2 minutes or so of placing the sensor, it read ~ 110 degrees, outdoor temp was 76.

This morning, intake temp (I'll abbreviate to IT - intake temp, and OT - outdoor temp) was 76, OT was 71. Within 1 minute of leaving my place, the IT read 72 and OT was 73. The IT for my entire drive down backroads and the highway to work stayed within 0.5 to 1 degree of the OT. At a stoplight, the difference climbed to ~ 5 degrees (76 OT, 80.5 IT). However, immediately upon moving away from the light, the difference went back down to 2 degrees.

So based on my morning experiment, I see absolutely no need for extra hose connecting the intake manifold to a "cold air source" as the engine is delivered air at outside temperature already, at least with the resonator assembly removed.

Not sure if anyone had done this experiment before, but if not, I thought you all might be interested. I'll post again after driving this afternoon when it gets more like 90 OT, I'm expecting similar results though.

 

Hmm. interesting. I'm looking foward to your results and will check back later on this evening.

 

Report #2

It was 91 leaving work this afternoon. When I started the car, intake temperature was 99. It warmed up to 101 while waiting at stoplights, then went down to 93 on the highway and stayed there till I got off

Seems like on all highway driving, regardless of the temp, the air at the intake manifold is within 1 degree of outside air. This is good, and makes a CAI un-necessary

However, in doing some slower speed driving around town, under 40 mph, I found that my intake temp fluctuates between 8-15 above that of the temp outside. So a CAI may make a bit of a difference driving around town. Although, this only goes for cruising. When I was accelerating, the temp dropped rapidly down to within 3 degrees of outside.

So my conclusions from my little test are that a CAI won't make any difference in air temperature as it goes into the intake manifold while accelerating (which is where we all want the colder, "more powerful" air)

Hope some of you find this interesting

Now on a side note, whether or not a CAI makes more power due to better airflow, that makes sense. But any power gains seen are NOT from colder air reaching the engine!

 

In my experience, its the resonator that restricts the power. Remove the resonator chamber and you gain more power and a bit more noise. Personally I like the engine noise during acceleration, its at an acceptable level.

 

I think that your "test" proves that the CAI will provide even better results, because of it's location in respect to the "hot" air in the engine bay. It might not be making the air cooler, but it's taking in air flowing under the vehicle (in most cai applications) and feeding that denser air in to the IM.

So while the outside tempeture might be the temperture recorded during your test, an aftermarket CAI such as comptech, AEM, etc should show lower numbers in regards to temperture entering the IM.

I think the concept applies to the human body, where the actual temperture is x degrees, while your body (dePending on wind factor) might feel higher or lower than it really is.

I believe a similar principal applies with a CAI obtaining "colder" air flowing under the vehicle vs. the stock air box obtaining air predomently around the hot engine bay.

My

 

I think there is some mis-understanding... The temperatures I recorded at the intake manifold, i.e. where the rubber flex tube meets the metal manifold, were nearly the same as the outside air. If the air there is the same temperature as the outside air, then how could a CAI get colder air? It doesn't cool off air, it just pulls it from outside, so the absolute 'coldest' air it can get is that of the outside temperature. And any air that is heated up in the engine bay that might get pulled into the intake will be exhausted within a few seconds, as a high amount of air flows through the engine.

 

Though the experiment was well done, your measurement location is incorrect. You need to measure IAT at the IM location... Measuring the temp at the Pre-TB will ALWAYS yield a temperature similar to OT, of course. The purpose of a CAI is to draw the air directly from the outside and prevent IAT from the IM to heat the air before fuel mixture. Because this air will always be more dense than IM temp, this air will yield more efficient when introduced to the combustion phase, hence more power.

If your results were true, dynos and racecar technology have all been lies. You can further reduce IAT by placing non-heat conducting materials between the block, IM, and TB... Such as thermobloks.

 

Temperature is only part of the equation. There is also resistance to flow, resonance, etc. After all, how could explain the HP and torque difference between an Ice Box and an Injen CAI.

Get a dyno and post it. That is the only way to truly compare. But then again, people who dont spend money an a CAI certainly wont find logic in spending money on a dyno. Otherwise, this experiment is useless.

Catch 22...

 

wheres that at. can u show me. u m ean like the exaust or wahtever.

 

Do you ever do a search before asking a question?