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.



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 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 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

[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 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.