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DIY attempt at homemade CAI

16K views 25 replies 12 participants last post by  csmaan12 
#1 ·
So I was rather bored the last few weeks, and was looking for a way to "improve" the current intake of the car for as cheap as possible. Preferably with things I already have in my garage. So I came up with an idea that I'll be trying next week when I have some free time.

Basically what I'll be doing is using the stock air box, with a K&N drop in filter (I know, I know, but I love the sound!), removing the resonator, and using some of the stock parts, to send a pipe from the air box to the inside of the wheel well for cool air, so as not to suck up the hot air it currently is.

So far what I've done is.

1. K&N Drop-in filter
2. Removed the little rubber elbow that connects air box to resonator
3. Started forming the contraption that will go into the wheel well, using the rubber elbow I removed.

Here's a picture of the monstrosity I've created so far.



Its very crude right now. I did sand and plasti dip the pipe because it looks ugly, and it will be black and not really noticeable when you open the hood.

Unfortunately it feels really bulky, and I'm afraid that those clamps aren't enough, so I might cut down the pipe a little. Only thing I need to figure out is how to make a "velocity stack" to put on the inlet. I MIGHT dremel out the ribs inside the airbox, but I'll do more searching if they actually make a difference in sound/performance first.

So far the only costs have been the $50 for the filter which I already had, but its not needed so I'm not counting it for the actual cost of all this. The pipe I also had lying around from an ebay intake I had a very long time ago, which was like $30, but they can be had much cheaper if you look around.

I'll try and get things rolling before tues/weds, but I have to go to work so I probably won't get to it until those days.

Thoughts, comments, is it a waste of time haha?
 
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#2 ·
not really a waste of time , you can defenitely make this into a moce project there are other diy dais out there for the tsx you just have to search a bit... as for a velocity stack jist buy one from ebay they have them for like 30$ shipped either way GL with your project keep up posted trust me your not the only one looking for CAI on a budget .
 
#4 ·
I'm gonna take a look around for the velocity stacks, I saw some on Amazon for like $15. I'm pretty sure they're rubber which is perfect because I can find an easy way to get it on the end of the tube.

I have to see how it fits first though because it may not look it, but its pretty heavy to be just dangling from the air box by just a clamp. Might have to cut it a bit shorter to shed some weight off it.

Tuesday's gonna be a busy day. Retrofitting projectors on a 9th gen SI, AND trying to figure this thing out, gonna be fun.
 
#6 ·
Velocity stacks are made out of metal or plastic, depends which one you want, they definitely make some gains over not using one. There are some companies that make a velocity stack and filter combo as well, which work great!

I don't see the need in dropping $200 on an intake, I had an extra filter laying around from the turbo on my other car, perfect fit!

 
#8 ·
This is probably the set up that will give the most power gains. A short intake works best, better when a velocity stack is incorporated.

The only problem is heat soak, which will rob you of the gains.
Some sort of cool air ducting to the filter, from either the grille area, under fender or a hood scoop would be the go.
 
#9 ·
3 inch

This is probably the set up that will give the most power gains. A short intake works best, better when a velocity stack is incorporated.

The only problem is heat soak, which will rob you of the gains.
Some sort of cool air ducting to the filter, from either the grille area, under fender or a hood scoop would be the go.

Yea, I'm not too worried about that as more air is hitting the filter vs using a closed box. Still has air coming up through the factory inlet too.
 
#10 ·
Okay here's the finished result. The picture is what the intake looks like now (almost can't even tell). However more ideas sprung up while I was doing this yesterday!

Anyway, do I feel anything different? I want to say its more responsive, and the car doesn't feel like I'm "pushing" the car to actually accelerate, but its probably placebo, and its what my mind wants me to think.

First (pic of intake).

Pardon my dust. See can't even tell I did anything to it. Forgot the pictures inside the wheel well, but its just a pipe connected to that rubber elbow, not much to see. Probably more fun to see all the blood in there, from when I was fighting with the resonator.

Now for my idea, and this is where I'll need opinions from you guys, because unlike what I just did, this may actually be of some benefit.


Here's a professional draft of what I'm thinking of doing.

In other words, I'm thinking of making the airbox a "Chamber" and putting a cone filter on the pipe that is now in my wheel well. Obviously I would remove the drop in filter, I'm not gonna double up on filters here, and maybe I'll grind out the ribs inside the airbox. I think this will be of actual benefit as opposed to the placebo benefit I think I have after that. Best of all, it will still look stock.
 
#13 ·
It's an interesting idea to use the airbox as a chamber. I guess what you are doing is isolating the filter (which is always a bit restrictive) and hoping that the air is still enough in the box that the intake virtually starts where the intake tube enters the airbox. Kind of like a short ram air intake with pre ducting.
What I'd be tempted to do is add a ram tube at this point, hopefully smoothing the airflow from the airbox to the TB and try to alleviate swirling at that point.

I've had a lot of experience dyno tuning motorcycles, and one thing that always stuck out was that using a large a volume of airbox (they are actually 'still air boxes'- to create a pool of air as free of swirling) as possible is always beneficial to driveability as far as power characteristcs are concerned. Take the airbox out and low to midrange always suffers at the expense of top end power, (which rarely gets used outside of drag racing).

So your idea may just work.

I'd be interested to hear the results for sure.

On another note I've decided to go the SRI route, as pictured here.




I like the stock rubber intake because of the increasing diameter, and also because it's rubber, which is a much worse conductor of heat than metal. I'll use a filter as pictured with a built in ram tube such as a Blox filter.
I'm inclined to leave the stock resonator and piping in place in the hope that it provides some cool air and perhaps play with some heat shielding.

A question.

I haven't pulled the intake tube off yet to measure it to get a filter set up , but the diameter where it fits onto the airbox looks to be at least 3 1/2 inches.

I notice Matt said he fitted a filter with a 3 inch inlet, but this looks too small for my inlet. I'd be inclined to go for a 3 1/2 inch filter ram tube combo.

Has anyone done this?
 
#12 ·
Well it would still have the filter, it would just be at the "end" of the chamber. Kind of like a home made version of those carbon fiber chamber intakes I've seen that cost an arm and a leg.

So when idling, the chamber would have cooler air "ready" for when the throttle opens.

Or are those chamber intakes different than what I am thinking they are?
 
#14 ·
1.hollow out the inside of the box.
2. Add K&N drop in Filter
3. Get a velocity Stack at the end of the pipe, could be any piping aluminum or pvc pipes from Home Depot (while your there get garage door liner for the DIY front lip)
total spent 80$ vs 150$ for a Comptech
 
#16 ·
Not to discourage you, but I have played with the lid and tube lately and honestly I think getting a CT-E icebox is the best way to go (if you are not looking for outright high rpm power). My comparisons were between CT-E lid and stock lid with bar removed + 06 air tube in 1500-3500 rpm range. The CT-E lid did improve the drivability and the effect could not be 100% replicated by removing the ribs/bar in the stock lid. The difference was in throttle and engine response, CT-E lid just pulls faster and more immediately. I haven't installed the horn yet so don't know what improvement it will bring, but I suppose the difference will be less noticeable compared with the open-end tube setup you have now.
 
#17 ·
No discouragement here, as the idea is to experiment so, if it ends up being a bust, then hey such is life. Plus the idea is to attain similarity, but for cheap/free.

I'm ordering a velocity stack off ebay today or tomorrow, if I find the right size, and will see how it changes with that. I just cant seem to find one with a 2.75" ID, so I may order a 3" one and improvise somehow.


As for the velocity stack for your icebox, I'd put that on ASAP, as it does seem to make pretty good improvements as opposed to a bare tube. Likewise from the testing they did at Heeltoe in their intake shootout. If I remember correctly they had a short ram intake, that they attached a tube to the filter with a velocity stack, and it made quite a difference as opposed to just the intake itself.
 
#18 ·
I first tried using small section of 3.5' piping and a K&N filter I had laying around as described here Do It Yourself DIY Acura TSX Short Ram Intake Cold Air Induction but I lost that low end "off the line" torque that was really important to me when I jump out into traffic and need to pick up speed quickly. (I have an automatic and this just ruined the driveability of the car.)


Then I saw a post (here) on creating a DIY Comptech intake with some cheap parts from pep boys. With the resonator removed and the pep boys pipe and velocity stack, I did not loose any of the low end power and gained some mid to high rpm output. It also sounds really nice too without being obnoxious. I cut 2 mall vents in the bumper to feed it cold air as shown below. This is the best compromise IMHO and I am really happy with the results.

CT intake lower section


Homemade Lower section (Pep Boys)




 
#20 ·
I actually saw your write up on this a while back^^^... My car is going in for paint on the 9th and when they have the front bumper off I will be doing this setup with a shaved oem box and k&n filter with velocity stack behind cut fog grill. Going for best bang for less buck!! Lol
 
#22 ·
I did the DIY short ram with 3.5 inlet cone filter attached to 3" PVC (previous setup was CT icebox) and I felt better response under 3k RPM and some loss in mid range.

But I'm a big believer in placebo also so whatever lol gonna expand on the shorter intake length though, I think the lack of air restriction is really helping despite the obvious heat soak
 
#23 ·
After reading these posts I said "why the heck not?" and went to advance and got a Spectre cone filter for $27 today. It has rings to put inside to allow it to fit different sizes. If you remove both rings it fits perfectly over the stock tube coming from the throttle body, and clamps right up, no piping needed.

All of this took about 5 minutes to remove the box and add this.

I took it around the block and was surprised that there is no noticeable sound increase except at WOT. I thought it would sound like crap but the little I heard I liked.

I'm gonna drive it around tomorrow and report back with pics. Previous setup was a homemade icebox.
 
#24 ·
Lol I had the PVC pipe on mine, and for some reason the the part of the pipe that was attached to the filter had a yellow ring around it when I took it off, not sure what that's from but keep it in mind.

And that stuff is hard, I tried scraping it off and it wouldn't come off, very strange, inside the pipe was clean though.


EDIT: Btw, how do you guys that go the home made SRI route, how do you support the filter/rubber pipe? I had to do it with 4 zip ties and a metal wire which looked ghetto as hell.
 
#25 ·
Sorry for the thread-jack. I'm gonna take some sound clips and post elsewhere next week. Just wanted to continue the DYI SRI talk while we're talking about DIY CAIs.

OK here's a few pics of mine. This cost $27, it fits perfectly around the stock air tube and clamps on nicely, then lays nicely on the bottom half of the air box without any rattling or noises. In my case, it was previously de-snorkeled (baffles) and I had the homemade icebox already. So I am still getting some cooler air from underneath being fed right onto my new homemade SRI.

For $27 this piece is actually very well made, I was surprised. I drove around all day in the 90 degree heat, interstate and plenty of vtec, afterward I parked and popped the hood, the filter is not burning hot as others have described. I think my homemade icebox, or what's left of it, is feeding enough cool air into this thing to keep it from being too hot.

Of course with shorter piping and more filter there is a HP gain, but heat soak probably eliminates this. Still, the sound is another pleasant surprise, you only hear it when you punch it, and it's nice and boomy rather than raspy. I can't believe I didn't try this earlier, it's excellent. There may be a bit of a gain in the butt dyno but it may be placebo. At this point, the TSX is just slow anyhow without a ton of money put into it; I am happy with the sound and am gonna keep this setup.



 
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