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ive been thinking bout making a custom aairbox for my td42 turbo and i want to make like a barrel with 4 inch in and 4 inch out with a big long pod filter inside, will this filter well enough if kept clean and will it flow extremely good? i wanna have 4 inch all the way from my snorkel through the filter to the turbo...
 

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Pod filter LOL do a search on K&N filters or the like on here..... you are best off with something donaldson like or original filters.... Pod or oiled filters DO NOT suit a 4wd.
 

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maybe go the 4 inch on the snorkel side because its so long. three inches is plenty between the turbo and the filter if you use long smooth bends.
I use the 2nd biggest k&N cylinder shaped filter they make. I worked the size out for 30 psi (three atmospheres of air used by the engine) at 4000 rpm assuming 100% turbo efficiency then doubled it for dusty conditions.
Look in the bowels of the K&N american website there are some good airflow formulas buried in there somewhere. calculate the air you will use. then look at the flow rates of the various filters that will fit under your bonnet on the donandson site. Then forget about a donaldson because they just don't flow enough. Lots of people use them but if you actually engineer it instead of just follow others you will see that they are wrong.
How much boost are you running and how many revs do you give it normally?

The only reason I'm using a K&N on that particular engine is because it will be lucky to survive to 20,000km. Use a paper filter. Adapt a factory airbox off a late model XR6 turbo or a v8 commodore and use the standard ryco paper element in it.
If you want to you can fit a piece of bird cage mesh across the inside of the engine side of the airbox just in case the paper element gets damp and collapses, but these days they have a lot of long fibres in them and hold together even if wet.

Believe me, with the amount of air a TD42 uses you will soon be sick of servicing your filter.
 

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hey mate you can get good filtering pod filters from the states called AEM air filtersi bought a dry flow 1 cost $80 del. I have done what you are talking about i made a 8 " barrel and got the ends laser cut out i will post some pics tonight.
 

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have a custom alloy airbox with a pod filter in my bus (100% off road) and am fitting a pod filter to my street patrol in the eng bay but will airbox it down the track to get the cold air in them. get a pre filter for the pods that fit over them and they are good for offroad use. a lot of the fast track buggies run them. agreed they are not as good in standard form but with the prefilter they are better.
 

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i painted it the same colour as the car turned out not to bad i think. since only running a 3" snorkel i have left a 4" hole in the front of the box that also has a 5" cap that i can bolt on.
 

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if you research aem air filters you will find alot of people in the usa use them in there desert racing vehicles very high quality product and washable.
 

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my pod is 9" long with 4" inlet, i think they have cfm ratings on the aem web site. i run 30 psi through mine and with the 3 " snorkel can't notice any difference, makes the same boost at the same rpm but havent had it on the dyno to prove it makes simliar power figures.
 

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hahah funny you should ask its aluminised exhaust tube left overs off a tug boats exhaust hahah. and all the ends are stainless.
 

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Sweet looking air box I think I may borrow the idea aswell
 

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I designed mine around the GU filter and stick with using the genuine Nissan filters. It bolts in place of the GQ pre-filter housing. It has 4 inch inlet from a stainless snorkel. 3 inch outlet. It probably is a bit small but I didn't want to move the overflow bottle and second battery.


 

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Thanks guys.
I can't claim credit for the fabrication. I only measured and drafted it. A stainless steel fabricator owed me a favour. I dare say these would be cost prohibitive to mass produce. I have no idea which has the higher cfm rating. I do like the donaldson products but just don't like how much space they consume.
 

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Thanks guys.
I can't claim credit for the fabrication. I only measured and drafted it. A stainless steel fabricator owed me a favour. I dare say these would be cost prohibitive to mass produce. I have no idea which has the higher cfm rating. I do like the donaldson products but just don't like how much space they consume.

Yes that certainly is a down side, especially with those (like myself) who want to keep the OE coolant bottle and an aux battery.
The reason I went with the DTS cast version of the GU box. For extra filtration, in the scrub, going a Donaldson pre-cleaner:

http://www.donaldson.com/en/engine/support/datalibrary/000207.pdf

Should pay for itself with main filter replacements.

Not seeking high PSI though as set up for touring.
 
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