Write-Up: Custom CAI

Before any construction of the intake was done, I conducted lots of research. I looked at pictures of peoples intakes and I looked at the instruction on how to make a FWI. Once I got the research done, I was ready to start to build it. There were a couple of things that I wanted the intake to have. I wanted to use 4 inch pipe, to use a 9 inch filter, to keep the coolant reservoir in place, and to seal the filter from the engine bay.
Materials I used: Plexiglass (I used ¼ inch), 4 inch PVC pipe, 45 degree PVC bend, K&N 9 inch filter, a rubber reducer to attach the pipe to the throttle body, Reflectix, aluminum tape, and miscellaneous tools.

The first step I took was to remove the airbox and the tube. One thing that I noticed with the stock tube is that it is 4 inches where it connects to airbox, and then it tapers down to fit the throttle body. Another thing that I noticed is that the intake tube had some little box hanging off of the bottom. My guess is it is some sort of silencer.

I used cardboard to create a template. I used a compass to trace the outlines of the car to the cardboard. Once I was done with the template, it was time to trace it onto the Plexiglass. Once I got the pieces cut out, I noticed that I had to bend one of the pieces to make it fit with the other one. I put it into the oven and heated it up just enough so that I could bend it. I carefully drilled two holes to connect the two side pieces together. Because of the way the Riviera is designed, I had to assemble the airbox inside of the engine bay. I then created a top for the box and drilled a hole in the side for the AIT sensor. The box pulls air from the filter and behind the headlights.

For the intake tube, I had to use a 45 degree bend. I cut off the end of the bend so that it would fit into the reducer. This changed the bend a little bit so that it wasn’t as severe. Once I was done I wrapped everything in Reflectix. I wrapped the intake tube and the inside of the box.

There are a few things that I would have done differently. One thing that I would do differently is use a smaller filter. I wanted to use a 9 inch to see if it could fit in there. But truthfully I will probably never outflow the filter on my engine.

Creating this box was a lot of work. If you didn’t want to spend as much time on it, you could always create the box out of Reflectix. The performance difference between the stock airbox and this was a lot. With everything stock, 0-60 times was around 7.8. With a gutted airbox it was around 7.3-7.4. After the box in 30 degree weather it was 6.43. I would say it averages around 6.7 seconds in 70 degree weather. As you can see, it made a big difference.

Now onto some pictures...



This picture shows the tight clearances

Nice job!! Very clean engine, too.

AA wrote:

Nice job!! Very clean engine, too.

Thanks. It took a long time, but was definately worth it.

Nice work. Wish I could find the time to put together something like this.

REALLY??? 0-60 in 6.5 seconds JUST by doing this mod??

98riviera98 wrote:

REALLY??? 0-60 in 6.5 seconds JUST by doing this mod??

For my car, yes. Your car could be faster or slower. The day when I got that time was pretty much perfect conditions. My car felt very strong that day. In the summer it averages around 6.7 seconds. My car felt good gains when I switched from the gutted box to the CAI.

hmm must be my WARM AIR INTAKE LOL

first of all tight work mane, much respect. would u recomend this for sunny hot south florida weather too? because as you know there is no such thing as "cold air" out here, even when your driving 70-80 mph...
good work once again mane

dadeboy305 wrote:

first of all tight work mane, much respect. would u recomend this for sunny hot south florida weather too? because as you know there is no such thing as "cold air" out here, even when your driving 70-80 mph...
good work once again mane

Thanks for the compliments. I would recommend using a CAI like mine anywhere. Insulation would help even more down south where it will be much hotter. You probably won't see as much of a gain as we do up north, but it would still worth it in a hotter climate.

appreciate it man. as of right now i "gutted the air box". took out the red junk and the grey box, but i should probably get a cone huh?

dadeboy305 wrote:

appreciate it man. as of right now i "gutted the air box". took out the red junk and the grey box, but i should probably get a cone huh?

Build yourself a FWI.

I'm curious as to just how much is actually gained from gutting the airbox.

I started the job and then took a second look once it was apart, not being a rocket scientist it's hard to imagine the grey and red pieces of plastic doing anything other than directing flow into the tube.

Without these pieces I was concerned there may be turbulent air creating a chaotic flow and actually working against what we're trying to accomplish.

What I hav'nt seen are write-ups about removing the screen located up next to the throttle body but feel this would be more in line with increasing airflow, although I don't know if it's removeable or even a good idea to do it...I'll toss it out for discussion!

Quote :

I'm curious as to just how much is actually gained from gutting the airbox.

Probably around 5 HP with a high-flow filter installed.

Quote :

I started the job and then took a second look once it was apart, not being a rocket scientist it's hard to imagine the grey and red pieces of plastic doing anything other than directing flow into the tube.

They quiet the sound of the supercharger. lowering NVH levels. They also limit the amount of air coming in the intake. For 240 HP, it's fine. To make more, it's a restriction.

Quote :

Without these pieces I was concerned there may be turbulent air creating a chaotic flow and actually working against what we're trying to accomplish.

A supercharger doesn't care about turbulence or chaos, it just needs a constant supply of cool air, as much as you can throw at it. To think of if another way, any calming or alignment of intake air will be disrupted once it reaches the rotors.

Quote :

What I hav'nt seen are write-ups about removing the screen located up next to the throttle body but feel this would be more in line with increasing airflow, although I don't know if it's removeable or even a good idea to do it...I'll toss it out for discussion!

The screen is actually there to stabilize the air flow near the MAF sensor, so it can get an accurate read. If you take this out, air flow will increase, but you risk the PCM not prescribing the proper A/F ratio. Some have reported lumpy idle without the screen.

Its a car part now wrote:

Short rams are defiantly HOT air intakes. I wouldn't want to see the IAT if it was 90 outside. If it was 90 out the intake would be 150? That would probably make the pcm pull some timing, and then some more from the KR it would cause.

I took some measurements today of my IAT (CAI-4" -16 gauge steel, heat painted, header wrapped, painted again) I then put a single alum sheet blocking the radiant heat from the bay (with a little reflux, nothing major, and not completely boxed in...I'm fabbing the top now).

cruising 40mph, off gas....45-66 degrees
light throttle 30-40mph........up to 85 (blip at 90), off throttle back to 40-60 degrees
WOT 30-60mph...................solid 80 degrees

Outside temp is 85 degrees and humid. IAT never went over 90 at a lite throttle, WOT was much cooler. 0KR. IAT installed into the intake, just passed the filter.

How are you seeing IAT of 45º when the ambient temp was 85º? Or did I read that wrong?

I really like the construction of that CAI. It's clean and well planned!

AA wrote:

How are you seeing IAT of 45º when the ambient temp was 85º? Or did I read that wrong?

That was correct, I was seeing 45-65 degrees while moving at 40mph (according to the Aeroforce). I'm assuming the air flow was the cause.

RidzRiv wrote:

I really like the construction of that CAI. It's clean and well planned!

Thanks! I didn't want to go with the FWI only due to the rain. We get a lot of rain here and I don't want to hydrolock another vehicle...lol.

Imo, those readings are not accurate. I recently installed a precision IAT sensor in my FWI tube. It reads within +1º/-3º of ambient at all times: on start-up, during cruise, WOT. The only time it varies from ambient is when the vehicle stops moving, IAT will climb slowly as the air heats around the car. Getting IAT of less than -3º below ambient may indicate the sensor isn't functioning properly.

PS - I had an IAT sensor that performed similarly to yours. It read -10º ambient, then -20º ambient, then finally it failed. Examining the sensor showed the leads had oxidized over time, changing the resistance characteristics. This type of behavior isn't always a bad thing, as you'll get a timing boost as a result; just understand it's one of those 'happy accidents'. Keep an eye out for KR.

I did think those readings were strange also, but hey, Ill take the added timing .

I did like that it was constant during WOT. It was strange to me that while cruising 40mph off accell it was reading 45, then the second I touched the accell it was up to 85-90. Never over 90 and constant during WOT. I'm going to take more visual readings (Aeroforce always set to KR and IAT). If the sensor starts acting erratically, maybe Ill look into an Omega, but for now it looks good. What I DON'T want is KR or any high temp readings, and the fact that I'm not seeing KR leads me to believe that the readings might in fact be correct (or at least not way off).

EDIT: Maybe the stock IAT isn't that precise to begin with...kind of like a narrow band o2 vs. a wide band o2. With narrow your either lean or rich, with wide you can be anywhere in-between. Could be the same for a stock IAT vs and aftermarket (Omega). With the stock your either cold or hot, with the Omega you can be anywhere in-between.

The OEM is fairly accurate, but not as quick to respond. It surprises me that your sensor adjusted to WOT so quickly. Mine was delayed. Another surprise is the fact that your reading goes up during throttle application. Mine completely opposite, cooling under WOT, moved back to ambient as soon as I let off th gas. This would seem consistent with the wind chill theory.

For $20 shipped the omega is an easy way to confirm if what you're seeing is real. Could be you've discovered a new supercooled intake design!

This is one of those little things that can cause 'mystery KR'. I bet most don't think to check their IAT readings and consider the timing boost could be the cause of it.

Ill take some more readings to be sure. I may want to hook up the Genisys just to make sure the IAT is accurate, The aeroforce reads what the PCM reads, not the sensor itself (correct me if I'm wrong).

Yes, the Aeroforce reads through the PCM. Imo, one way to know if your IAT sensor is accurate: park the car overnight and check the IAT value when you turn on the key, before starting the engine. The IAT should match the ambient temp displayed on the climate control. If coolant and trans fluid temps are also near ambient (this takes 12 hours or more), you can be sure the engine bay isn't skewing the reading. Even so, the engine bay could only increase the IAT, not decrease it.

HAHA! I'm a fool! Going back and forth in this thread got me thinking. Went outside, and checked....I had it set to IAC, not IAT...lol. Gotta lay off the green.


Anyway, I'm showing 70 degrees on idle (67 degrees outside now). Let me take some measurements and Ill update my findings....ugh *smash head on dash*

If you can keep IAT near ambient while driving, you've built a VERY good CAI. If it reads high, that's normal. Most CAI designs just can't beat a FWI in that regard. Good luck!

LOL you were reading IAC counts