Stock Airbox + CAI

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/v2...6/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!!

are you sure your measurements are right?

Quote:

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Originally Posted by chunky

are you sure your measurements are right?

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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??

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!

Quote:

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Originally Posted by 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!

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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..

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.

Quote:

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Originally Posted by 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.

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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...

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

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/v2...6/DSC00046.jpg
http://img.photobucket.com/albums/v2...6/DSC00047.jpg

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.

^^^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....

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.