Factory intake/air box design

[TurboJ]

R.O.R, thanks for your input.

I'm still not going to fit a cone filter though..
I believe in proven designs, and I have seen a lot of scientific research concerning factory air boxes.
They work amazingly well, which is no big surprise really, given the resources the car makers have, and their attention
to detail, governed not least by emission laws and selling a competitive product...

A cone filter can be of benefit on some engines, but in those cases a good cold air feed and heat shielding is a must, not just a nice plus.

Without those features, I have never, ever seen a cone filter making more power / torque throughout the rev range compared to a stock setup.

On VAG systems, a cone filter will usually reduce power slightly, and in some cases, limit torque quite substantially.
If you have a small turbocharger, you can boost away these drawbacks, but why would you?

Also, If you use a cone filter, you have to make sure the cone's outlet or the connection to the intake tube is bell-shaped and smooth, otherways
there's a 100% certainty it will hurt power levels.

I like to always look for the best designs and best features. A regular cone would work fine for sure, but since I know there are much better designs
readily available, that's what I want to use and pursue.

Aki uses stock air boxes, by the way. He's done a lot of testing and it's quite surprising how well these work even on highly tuned engines.

On most people's VAG IDI engines the stock intake will always be the best choice, or at least very close to that; here's some science on that
(the mk3 ABF engine has the same air box as the mk3 1.9 TD IDI and shares the key features with the mk2 air box)

http://www.clubgti.com/showthread.php?199237-Toyotec-s-how-to-make-your-MK3-16v-breathe-on-a-budget-Part-2-added-14-12-09

The only doubt I have is the actual limit of the stock box. It flows excellently, but up to how far?
The intake trumpet is the key limiting factor, since I know that a mk4 air box with an OE filter achieves 350 hp on gas engines. The mk4 filter's flow area is within 5 per cent of that of the mk2 EcoTD.

[RabbitJockey]

I was thinking instead of making one maybe find one from another bag car that makes your power goal stock like an Audi v6 or v8 car.  That or maybe make a trumpet dimensionally 3 times the size of the stock piece

I have thought about this many times, but this isn't an option for me as the mk2 EcoTD airbox is the biggest one that will fit the space I have available.
However, I'm looking into fitting a trumpet from a ~200 hp diesel car - that would be kind of easy and safe.

Currently I'm thinking making a plastic system out of a funnel of sorts, and some bass reflex tube ends. An a cold air feed to that. Lots of work still..

Yeah I meant take the trumpet from another vag car

[gldgti]

The mk4 filter's flow area is within 5 per cent of that of the mk2 EcoTD.

For another option - I have an '07 PD TDI (skoda) but the airbox is the same as all of the current generation TDI's (1.9 and 2l).... interestingly, you  can swap the filter element directly with the element from a Mk1 airbox!

It is not supposed to fit - the new TDI filter is about 3mm larger in length and width but because of the foam rubber outer you can still do it. However, the current gen filter is almost TWICE as deep/thick... so the filter area is also alomst twice as much.

Also - the current tdi's airbox is a much nice overall shape for fitting into mk1 engine bays than the mk3 type :-)

[RabbitJockey]

When you get a mki Mann filter those suckers are thick.  When I buy the filter at napa which is wix brand I buy it for a jeep wrangler since it is almost as thick as the Mann filter and a similar size.  I used to work there and napa has very good systems for finding things by dimension

[TurboJ]

Could you guys share a pic of the mk1 air box that you're referring to, please?

Even so, I'm using the mk2 EcoTD air box, and there isn't a possibility really to increase the filter size;



.. the space is limited by those plastic supports you see in the picture, and if you cut them off, there wouldn't be a level surface to hold
the filter straight.

But, I believe the standard filter should be quite enough; it's mainly the lower part of the air box that is limiting power.
(The OE snorkel system is removed in the picture, but that leaves the opening a bad shape for air flow; there won't be positive pressure effect in there at least!
I'll build some sort of snorkel system of my own with bell-shaped ends in there; that should do the trick..

[RabbitJockey]

I'm talking about the non turbo mki air box,  you can just get a much thicker filter nothing really to show.

[R.O.R-2.0]

I'm talking about the non turbo mki air box,  you can just get a much thicker filter nothing really to show.

CIS gasser took the same element..