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Old October 11th, 2018, 16:03   #1
eddieleephd
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Default !!! Vw oem cold air intake !!!

Welcome to the
!!! OEM COLD AIR INTAKE !!!
Below is the best possible routing and design for a cold air intake on a VW MK4 unless modified to some ungodly HP!
Reality is that having a vacuum within the air box for air to expand into cools it down. This is accomplished by utilizing a sealed box that you control the dynamics and operation. Aftermarket CAI's generally have poor design and very few have a sealed plenum making them Warm and Hot air intakes, not Cold Air Intakes.
Below is the tube that wraps around the battery, it's sized larger than the lower boost pancake tube. (which is a far better place to consider an upgrade to the OEM system with an OEM designed part using the upgrade metal lower boost pancake tube.)
The tube below is designed with specific flow rates being considered and on a stock to fairly heavily modified engine it is more than adequate. It's actually designed to create a low pressure, to vacuum within the plenum to cool the incoming air.
The added tube on the upgraded 1.8T plenum box (in one of the last pictures below) that points towards the engine is the OEM upgrade for vehicles with greater modifications that might occasionally need to draw a bit more air than the tube around the battery can provide. This is the only modification to the stock air box that is affordable and will actually make any improvement, luckily it can be found in the junkyard on an old car for a much better price than an aftermarket CAI.

Cold air duct around battery:


Where it comes out in front of the battery and behind the headlight


This is the area beside the battery and to the right is the opening for air to enter.


The same picture as above with the rear cover below installed creating the completed cold air intake. Notice there is no opening between the battery as the rear cover is specifically designed for this vehicle.


The inside of the rear cover


This is the bottom of the 1.8T air box to the left you have the added volume air valve tube that points towards the engine above trans.


This is the CAI installed
The picture below show's the bottom of the original ALH CAI filter plenum which only has one inlet for air.
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Last edited by eddieleephd; October 12th, 2018 at 04:18.
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Old October 11th, 2018, 18:29   #2
scooperhsd
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Do some reading.



The stock airbox is MORE than you will ever need, no matter how much you modify your car. And K&N oil type air filters are BAD for your MAF (certainly if left with too much oil, and maybe period).
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Old October 11th, 2018, 20:54   #3
ketchupshirt88
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Quote:
Originally Posted by scooperhsd View Post
Do some reading.



The stock airbox is MORE than you will ever need, no matter how much you modify your car.
And K&N oil type air filters are BAD for your MAF (certainly if left with too much oil, and maybe period).
Yea I’m pretty sure someone tested the stock airbox and determined it was adequate to
beyond where you would be maxing out the MAF sensor anyway.
Been a while since I read up on it... 200+hp comes to mind but i could be wrong.
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Last edited by ketchupshirt88; October 11th, 2018 at 20:56. Reason: Fix typo
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Old October 12th, 2018, 04:04   #4
eddieleephd
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Quote:
Originally Posted by ketchupshirt88 View Post
Been a while since I read up on it... 200+hp comes to mind but i could be wrong.
The 1.9T base I posted above was VW's solution, as stated in the original post, to higher needs for incoming air.
It will draw warm air through the added draw tube, however, if there's that much need for air a little warm air isn't going to hurt.

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Old October 12th, 2018, 04:51   #5
oilhammer
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BEWs have them too. But I doubt any of the diesels really are capable of moving so much air that the normal intake tract isn't sufficient. The turbocharger's inlet is the restricting factor, and it is barely bigger than a silver dollar.... seriously, it is less than 1.5" across. It is TINY. Even a bigger turbo mounted to an ALH is STILL relatively tiny and this is only a 1.9L engine that in stock or even mildly modded form makes very little usable power over about 4k RPM anyway.

I have seen a 212hp dyno plot from an ALH with the completely stock air intake intact, right down to the snowscreen and the OEM Mann air filter. If you want to go faster, the air inlet system is NOT the first place to start. It is probably #12.
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Old October 12th, 2018, 15:30   #6
eddieleephd
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Quote:
Originally Posted by oilhammer View Post
BEWs have them too. But I doubt any of the diesels really are capable of moving so much air that the normal intake tract isn't sufficient. The turbocharger's inlet is the restricting factor, and it is barely bigger than a silver dollar.... seriously, it is less than 1.5" across. It is TINY. Even a bigger turbo mounted to an ALH is STILL relatively tiny and this is only a 1.9L engine that in stock or even mildly modded form makes very little usable power over about 4k RPM anyway.
I have seen a 212hp dyno plot from an ALH with the completely stock air intake intact, right down to the snowscreen and the OEM Mann air filter. If you want to go faster, the air inlet system is NOT the first place to start. It is probably #12.
Seems like you're trying to tell me something that this post is absolutely all about. There's no better intake for the MK4!
You're right though, a TDI would likely never open the other tube to draw air. One more reason there is no CAI that would viably replace the OEM CAI.
Guess where I got the 1.8T airbox, the recipient 1.8T for the swap. Figured WTH, it's sitting there, may as well...
http://forums.tdiclub.com/showthread.php?t=491470
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Old October 13th, 2018, 09:22   #7
Franko6
 
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I hate big pictures and scrolling to read the post...

My Cummins, which is a stock 190 hp has a smaller air cleaner than my MK4. That must tell you something. I've never felt the need to
increase my Cummins air cleaner... (note: no scrolling necessary)

I thought they had a section for "Unnecessary Upgrades". If not, I suggest they make a special category for such things.

While your at it, you could install a 4" exhaust to eliminate back pressure.
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