I've always wondered about this. Once the intake manifold and TB heat up after running the car for a about 10 minutes, wouldn't the CAI be pretty much useless? By useless I mean the heat of the intake manifold (about 200 degrees) and TB is going to saturate the incoming air in heat. Am I right here? I don't think it matters how good the CAI works because once the motor is heat soaked, there's no way the incoming air can over come the heat generated by the block, heads, and intake manifold. I think the only thing that's gonna keep the engine cool from there on is the coolant and thermostat.

Dave

 

I think you are right, that's why some CAI for some cars come with a heat shield.

 

Your forgeting that the MAF and AAT reads. According to the Z32 FSM I have the ECU lowers the amount of fuel from the injectors as the AAT and MAF read hotter temps. Since you have less fuel you can't make as much power. These results can be confirmed on a techtom mdm-100 on a max with the same mods except on has a CAI and the other a pop or Stillen intake.

 

Wrap the intake tube in thermal tape.
It ain't pretty, but it works.

 

No, the CAI is still effective.

The air going through the intake tract moves so quickly that there's really not much heat transferred to it from even hot intake path surfaces. Even if the intake manifold is at, say 160 degF, that doesn't mean the air will be at that temperature. Rather, the air temp is a function of flow rate also...the higher the flow rate, the lower the air temp.

If the entering air is 120 degF (example for underhood filter), it can only heat up more by the time it reaches the ports. My guess is the air only gains maybe 20 degF or so for even hot 160 degF intake surfaces. So if the incoming air is only 90 degF (example for CAI), it will heat up a little more because of the larger temp differential, but still you're only talking maybe a 25 degF or so gain...in the end, the intake air will still be cooler with the CAI.

But this is all just theoretical...

 

The CAI gives alot more HP even if the car is hot than a JWT. It's not pulling in hot engine heat. That is the reason why.

 

What you have to remember is that an engine gulps ALOT of air as compared to the amount of fuel(ie.. 14:1) Since it's rushing in fairly fast, it's not being heated that much by the manifold etc...So if it's sucking in from a colder source, it won't heat up that much. Also the cai has the benefit of a longer tubing before the maf sensor. This is supposed to give good low end grunt vs a softer low end often experienced by cone users.

There was a big debate of cone vs cai on yahoo. Peak maf readings were actually higher w/ the cone. This seems to confirm the above theory about longer tube length and low end grunt(basic header theory here) as the expense of high end total airflow.

So you could run a tube for the cone but you would not get the tube length benefits of a true cai but you still get the high end air flow.

 

I think on a hot day (80 degrees) it ain't gonna matter what you've got. Your car isn't gonna be quick because even the air the CAI is pulling in is hot (120 degrees on the pavement). I did wrap my intake pipe from the MAF on up to the filter. It does keep the intake much cooler until the intake manifold and TB are super hot and start heat soaking everything.

Tonight it was in lower 70s and I took my car out for a 30 minute cruise with lots of stoplights and I did a few quick WOT runs. When I got home I popped the hood and the intake was cool and the intake manifold was barely warm. I had no idea how much 80+ degree weather really heats up the motor.
BTW, I've got a vacumn hose running from the underside of the bumper straight to the intake now. It seems to get some cooler air to the filter.

Dave

 

...I live in AZ. Had the Stillen HFI...trashed it. Car was slower. Put in a CAI from Max-Rev...much better...pictures if you want. Show&Go...gotta have both.

 

i would like to see pics

 

I bought mine for the tough looks and the bad *** sound!
CAI is always better. My only gripe about the place racing is what material is that thing? If it is metal than Ain't no way that is going under my hood! if it's ABS formed plastic then I'll buy one.
Metal = HEAT absorption (but it can cool faster)
Plastic = less heat absorption (but does not cool as fast.

choices choices, I like my growl! hot or not!

 

My car seems to do just fine with a "standard" intake. I mean I'm running high 14s with 94mph trap speeds all the while I'm spinning hard thru 1st (2.4X 60'). Plus I haven't run my car in weather any cooler than 80 degrees and humidity in the 70% range. I have no doubt, with traction, my Max is a mid 14 second car. I just don't really believe a CAI is gonna make the car much faster. Much of what makes any intake effective is the lack of restriction over the stock system, not necessarily the air temp going in. The Supra, RX7, GTP, and Grand National guys don't seem to complain much about not using CAIs and they've got super hot underhood temps due to power adders.

Dave