Stock Airbox + CAI

[dsp26]

OK.. firstly here is my intake setup and I want to implement a CAI/POD into the fender and remove the filter from the box.

http://img.photobucket.com/albums/v281/dsp26/DSC00020.jpg

Now thw dilemma is that for those with EGs, you know that the inlet to the box from the fender area is OVAL.. i need to calculate what size coupler can go over it...

generally the dimensions of the oval inlet is 10mm (~4in) x 80mm (~3.2in). Circumference is 320mm... I calculate this to require a 4in coupler... but how is it so when 2 sides are 80mm (3.2in)??? I was expecting like ~3.75in...

Thanks in advance!!

[chunky]

are you sure your measurements are right?

[dsp26]

are you sure your measurements are right?

I hope so... coz ignoring the OVAL dimensions i tried calculating the required spherical equivalent diameter using formula:

d = C÷3.14
d = 31 ÷ 3.14
d = ~9.87cm = ~3.95in

reason for the spherical calculation is coz being a rubber/silicon coupler i can force it over an oval.. just need it to be the right size.... reason i need it to be very close is coz you can only get silican couplers/reducers above 3.5" and their hard to force into an oval shape even with a clamp....

***EDIT***
also the above calculation is under the assumption 1in = 2.5cm??

[string]

An ellipse of major and minor diameters of 100mm and 80mm respectively, yields an approximate circumference of 11.1inches. A circle of diameter 3.55inches gives the same circumference. Assuming my numbers are correct, a 3.5" silicon hose should stretch over it with a little bit of persuasion.

All equations can be found on wikipedia (http://en.wikipedia.org/wiki/Ellipse) for your own verification.

How did you make the initial measurements of the inlet diameters and circumference -> they don't agree with each other!

[dsp26]

An ellipse of major and minor diameters of 100mm and 80mm respectively, yields an approximate circumference of 11.1inches. A circle of diameter 3.55inches gives the same circumference. Assuming my numbers are correct, a 3.5" silicon hose should stretch over it with a little bit of persuasion.

All equations can be found on wikipedia (http://en.wikipedia.org/wiki/Ellipse) for your own verification.

How did you make the initial measurements of the inlet diameters and circumference -> they don't agree with each other!

yeah i agree it doesn't make sense.. i'll take a pic.

straight end to end is 10mm and 80mm exactly.. circumference was measured with a string+ruler..

[bennjamin]

let me get this - you want to run the airbox as a baffle or run the pipe straight thru it ? ( IE hidden) Just run the exact same pipe dia. as your intake arm. Modify your "inlet" to the airbox aith a small amount of heat from a heatgun or even butane burner. This will let you reshape it slightly and make it a cylinder for the pipe you want to fit thru.

[dsp26]

let me get this - you want to run the airbox as a baffle or run the pipe straight thru it ? ( IE hidden) Just run the exact same pipe dia. as your intake arm. Modify your "inlet" to the airbox aith a small amount of heat from a heatgun or even butane burner. This will let you reshape it slightly and make it a cylinder for the pipe you want to fit thru.

hey benn.. nah can't do heat gun trick.. i'll take a pic of the box.. the inlet is gay.. goes into like 4 different shapes before going in the box hence why i couldn't run the cai thorugh like i did with the DC2/4 box...

but yeh, pretty much want the airbox to be empty and running a pod at the end in the fender... it's soooo restrictive even with a K&N panel... purpose is to retain stock look... I want my cai back but don't want the associated EPA troubles...

[rayb3na_]

cut out the stuff inside the box just l;eave the shell feed the pipe through there with some aircon piping to fit the size then hook that up with your pod/piping

[dsp26]

OK... halfway there...
ordered a 4in to 3in reducer coupler from the US @$40 delivered...

ended up being too big to go around the inlet despite how much i cut it...

i ended up cutting to a point where it wouldn't even fit so i thought of a better idea... put it inside and seal it instead!!! works even better as the silicone moulds to the oval shape... now i just need an exhaust shop to make me a 30° bend and the cai is sweet!!!

will write-up a DIY when its all complete and installed


http://img.photobucket.com/albums/v281/dsp26/DSC00046.jpg
http://img.photobucket.com/albums/v281/dsp26/DSC00047.jpg

[EKVTIR-T]

If I understand what your idea is.Having a pod connected to the bottom of the box with the box being empty and part of the intake path.
I have tried this and didn't yield good results.
To me,less torque right through to redline.
Gave a sort of empty feeling on acceleration.
Another down side but not important,it sounded horrible..
Look forward to your own feedback on it though.

[dsp26]

^^^yes thats the idea... but am.. damn... coulda told me the terrible news nearer to completion :p lol

depends on the filter though... i mite go back to a blitz style mesh one.. that thing sounded mean on my old cai.

i believe you though but it can't be worse than the stock airbox with K&N as it feels worse than having my old setup... i get this feeling that part of the poor results is the weird airflow/turbulance caused by an empty box....

everyone says stock airbox is good blah blah and K&N has good flow... but not in that square filter form.... given the same material a pod has far greater surface area of the same resistive material therefore less restriction as suction is spread over a wider area....

[EKVTIR-T]

Nah still try it.Better to get others experience and feedback too.
Did you ever try drilling more holes under the stock box?
Might free up the restriction a little?Just a thought.

[T-onedc2]

My reasoning for a drop in performance over a filter in box is the turbulence created when the air travels through the box upseting the smooth air flow to the throttle body, also the change in resonant frequency passing through the box may come into effect as well. Running a tube directly through the box may help.

[bennjamin]

Running a tube directly through the box may help.

i thought this was the plan ? IE use the box as simply a "cover" for the pipe underneath...that goes straight thru like a injen intake etc.

[dsp26]

Nah still try it.Better to get others experience and feedback too.
Did you ever try drilling more holes under the stock box?
Might free up the restriction a little?Just a thought.

still gonna finish it see how it goes.. overall budget including the piping is $60.. i've already got a pod.. quite a few unused ones actually lol

did that on my spare bottom.. worked a treat.. but still feels lacking


My reasoning for a drop in performance over a filter in box is the turbulence created when the air travels through the box upseting the smooth air flow to the throttle body, also the change in resonant frequency passing through the box may come into effect as well. Running a tube directly through the box may help.

yeah i think thats what EKVTIR-T is talking about... will still give it a try though...



i thought this was the plan ? IE use the box as simply a "cover" for the pipe underneath...that goes straight thru like a injen intake etc.
nah couldn't in the first place but wish i could... however the method you mentioned above works with the DC4/2 airbox which i've already done to the mrs car... it's coz the box hole is actually flat and round...
http://img.photobucket.com/albums/v281/dsp26/DSC00018.jpg

i'll take a pic of the inside of the EG box.. brb
http://img.photobucket.com/albums/v281/dsp26/DSC00048.jpg
excuse the light, had to use my torch coz of my crappy phone camera...

[dsp26]

OK.. also just did some measuring against stock reso box to get the bend right...

2 pieces of metal currently taped together until i get a mandrel bend made...

final setup should look something like:
http://img.photobucket.com/albums/v281/dsp26/maintenance/DSC00049.jpg

[rayb3na_]

das pretty gangster howd you attack the piping to the top of the box from the manifold?

[dsp26]

das pretty gangster howd you attack the piping to the top of the box from the manifold?

was a $50 black ebay SRI.. cut 2inches off it and lines up straight to the 3in airbox... don't let the coupler fool ya... theres actually no gap between the pipe and airbox inlet...

standard EG airbox is only 2.5in i think though... my EG2/6 bos is 3in so got the 3in SRi to suit...

[dsp26]

If I understand what your idea is.Having a pod connected to the bottom of the box with the box being empty and part of the intake path.
I have tried this and didn't yield good results.
To me,less torque right through to redline.
Gave a sort of empty feeling on acceleration.
Another down side but not important,it sounded horrible..
Look forward to your own feedback on it though.

OK... tested my dummy rig from the box to fender.... your report is exactly right...

- less torque right through to redline.
- Gave a sort of empty feeling on acceleration.

less torque part is understandable as per a normal cai.... felt happier above 4k-ish though and is noticable considering i filled up a full tank of mobil E10 93oct from bp 95oct...

and yeah empty feeling... feels a little more linear.... these results will definitely show up on dyno so i'll check it out in a bit... i'll try this for 2 weeks and update this thread...

[jdm_kid]

the air box is just a resonator then ? lol

[bennjamin]

its a baffle which slows down air speed even more ~ a completely stock airbox + resonator setup would make more power lol

[jdm_kid]

its a mutated whale penis lol
invest in a dc2 air box with custom intake arm

[T-onedc2]

its a mutated whale penis lol
invest in a dc2 air box with custom intake arm
uncomfortable for other whales I'm sure :eek:

Let us know how it goes.

[bennjamin]

i have a OEM whale penis (ITR intake + box) and that works fine. Do it and stop wasting ur time Ron lol

[dsp26]

i have a OEM whale penis (ITR intake + box) and that works fine. Do it and stop wasting ur time Ron lol

lol i'll test fit the mrs dc4 one again on the weekend and let you know.. pretty sure it doesn't fit in the delsol.

do you have a pic of yours from top down of engine bay.. or are you able to get me one... wanna do a comparo...

[bennjamin]

fits easy.

http://www.ozhonda.com/gallery/data/500/11072007803.jpg

[EKVTIR-T]

^ Isn't that drawing air from where the filter connects to the intake arm though?
Sort of defeating his purpose of a "cold"air intake setup?

[bennjamin]

the above ? it can be angled towards the hole seen ( and currently is)

Not that ive noticed a difference in its current location , compared to as above and sucking right behind the hot hot radiator.

[EKVTIR-T]

Ye just asking,thats all :)
Wasn't sure if it seals well where the hole is at the back of the box.

[bennjamin]

oh i gets - the back of the airbox is sealed via that small silver ring ~ its a spring loaded "clamp" of sorts and keeps the intake arm firm on the airbox.
Only issue is , due to age of this intake arm it flexes under load and makes the fabled annoying "whistle" under half / light throttle. Works fine tho.

Do it Ron.

[jdm_kid]

Do it and get unexpected kw gains on a dyno

[dsp26]

OK final report.

After much denial.. for my mrs to ask me "wtf does your car feel like it's choking" while in the passenger seat and while i'm redlining 1st/2nd to 100km/h on M7 onramp tells me enough.

switched back to my old setup after cleaning my very dirty K&N and it feels and sounds so much better...

for compromise of stock look and performance and sound the below mod works great.. going to try it with a foam panel... i still think the K&N panel is shit....
http://img.photobucket.com/albums/v281/dsp26/DSC00056.jpg

[vinnY]

just cut out the whole bottom i reckon, leave a bit of skeleton so it has some sort of structure left

i mean drilling random holes are fun but come on :p

oh if you want to experiment with a dc airbox i got one lying around ;)

[90LAN]

after u cut the bottom out
i reackon u should graft on a stainless steel fine mesh under neath so it still blocks crap getting thru but still lets it flow ?
just a idea

[dsp26]

mmk.. member EG30 posted this article in another thread which i found interesting:
http://www.autospeed.com/cms/A_110683/article.html

After cutting out the bottom of my box entirely i'm going to confirm that the powerloss and response is noticable after getting heatsoaked unless i make a blockage plate around the airbox too from the rad overflow to the strut tower.


so ladies and gentlemen.. I FOUND A SOLUTION using the original concept!!! here me out and use your imagination....

now the flaw with the original idea (which i've already tried) is that there is possibly A LOT of turbulance in the empty box which slows airflow.. the power loss is noticable as its also not rev happy

so using this picture as reference:
http://img.photobucket.com/albums/v281/dsp26/Intake/DSC00048.jpg (http://img.photobucket.com/albums/v281/dsp26/Intake/DSC00048.jpg)
http://img.photobucket.com/albums/v281/dsp26/Intake/DSC00049.jpg

What IF i used the spray foam (used for audio sound deadening doors etc) and sprayed the inside of the airbox then shaped a 2.5in intake tract??

This 'imaginary' intake pipe carved/moulded into the foam will be done identically to both top and bottom half of the airbox...

Now does anyone see any reason why this would act like a true CAI pipe from TB to fender?

[bennjamin]

erm.....didnt myself and others suggest to do this ages ago ? From what i understand you want the airbox look to avoid defects right ? Why not just go all out , get a plasmaman or injen intake and plop a airbox on and around it for th "sleeper" look ?

there is too much going wrong with your car ron stop touching it lol

[dsp26]

^^^nah it's coz i touch myself at night :p

gotta touch it.. i'm cut that youtube shows vtec del sols doing 15.1 bog stock :(


but how can i put an airbox around the plazmaman/injen? the eg airbox still has that inlet shape issue as can be seen from the first pic i posted above... even if i cut that enough to hide a pipe into there and into fender.. i have the problem of having to get a smaller primary pipe that actually goes inside the inlet at the top of the box...

sigh... back to some innovating in the corner of my room

[bennjamin]

all it takes is a steady hand , a scalpel , a small hand saw and maybe a file. You can make it fit snug if you take the time.
A typical injen or plasma etc intake is 3 inches i believe - Im sure you could even cut the outlet of the airbox off and run the pipe direct ....