Need Help with Air Filter differences? (Stock Vs CAI)

[pantha]

According to my Math:

For a 2.0 TFSI (BWA) engine with the filter element in the engine cover.

The stock air filter is:
Surf. Area of a panel: L * H
408 x 174 mm (38mm thick)

Panel Area: 70,992 sq.mm

A pod (Cone) filter (K&N part no: RU-3580) is:
Lateral Surf. Area of a Frustum Cone: Pi * (R + r) * H
3.142 * (76 + 51) * 127
Pod Area = 20,426 sq.mm

Now, I understand that the filter element is pleated, but, if we assume both are pleated (Which they are) then we can assume it a constant (For comparative reasons) and even if the pod pleats are twice the size as the panel pleats... it's still a LARGE difference...?

So...

Is the stock filter element WAYYYY too big for what the engine requires???

I also understand that the Stock paper element filters are more restrictive than an aftermarket "Hi-Flow" Panel OR pod filter. But there's a difference there of 3.5 times the area.

Can anyone explain or give input into this? Has someone tested static pressure in the intake with different filters? I dunno...

 

[S3Alex]

A lot of comparitive testing has gone into CAI Vs stock filters over the early stages of TFSi tuning,and whilst there's a lot of BS involved,most will agree that for a Stg1 remap,it doesn't really make much difference if you use a good CAI,the stock filter,or an aftermarket one,but as you increase the power,and airflow requirements,the better CAI's do begin to show a considerable advantage.

 

[pantha]

Totally Agree S3Alex. I get the fact that, the stock filter also gets ****** hot sitting on top of the engine. and moving it to infront of the battery with a pod, fixes the "Heat soak" issue. But, lets assume a higher stage tune. According to my maths above, the pod filter is less than half the size of the stock filter... would this not start choking the engine? or... like i said... is the stock filter is WAYYY oversized?

 

[S3Alex]

Totally Agree S3Alex. I get the fact that, the stock filter also gets ****** hot sitting on top of the engine. and moving it to infront of the battery with a pod, fixes the "Heat soak" issue. But, lets assume a higher stage tune. According to my maths above, the pod filter is less than half the size of the stock filter... would this not start choking the engine? or... like i said... is the stock filter is WAYYY oversized?

I think a lot of people focus on heat soak,forgetting that once the car is moving,and drawing decent airflow through the system,the biggest area for that issue shifts from the piping,to the intercooler,at higher stages of tune.

Yes,a cone filter may have apparently smaller area,than a pleated panel filter,but don't forget that it's also either pleated,or a high area foam filter,such as on most of the good CAIs,like ITG,revo etc etc.

I can't quote figures,and there are plenty out there,but I can speak from experience where we tried on my car to use a panel filter and to retain the stock induction system.
This sort of worked at Stg2,but failed horribly at Stg2+,where it simply ran out of flow,in part due to the filter,and part due to the restrictive stock induction system.

Turn it around again and look at this...





That untidy looking pile of pipework plus foam filter will flow more than enough air for 600bhp.

 

[pantha]

I'm looking at something like a 42 Draft Designs Alloy MAF, coupled (Via a 2.75" - 3" silicone Coupler) to 3" ducting, around the top of the engine to some sort of enclosure in front of the battery, that draws in Air from where the factory setup draws it.

This would retain stock fuel trims, and flow would be dramatically improved, due to the air not requiring to go all over the place, but instead, follow ONE pipe directly to the MAF.

I'm just curious that, if I were to do that setup, would a 6" cone filter be restrictive, or totally fine?

or... to throw a curve ball... if i can source some kind of other car manufacturer's airbox that fits in that space, and looks standard. it would obviously have a smaller "Panel" filter... based on the area it would need to fit in, something around 250 x 150mm (HALF the size of the stock filter) would a "Hi-Flow" filter of that size be restrictive?

 

[S3Alex]

I'm looking at something like a 42 Draft Designs Alloy MAF, coupled (Via a 2.75" - 3" silicone Coupler) to 3" ducting, around the top of the engine to some sort of enclosure in front of the battery, that draws in Air from where the factory setup draws it.

This would retain stock fuel trims, and flow would be dramatically improved, due to the air not requiring to go all over the place, but instead, follow ONE pipe directly to the MAF.

I'm just curious that, if I were to do that setup, would a 6" cone filter be restrictive, or totally fine?

or... to throw a curve ball... if i can source some kind of other car manufacturer's airbox that fits in that space, and looks standard. it would obviously have a smaller "Panel" filter... based on the area it would need to fit in, something around 250 x 150mm (HALF the size of the stock filter) would a "Hi-Flow" filter of that size be restrictive?

I don't know the size of the MAF on the 2.0TFSi,but if the one you're looking at is any larger,then you would need your mapping to be corrected for that.

It's perfectly possible to make up your own CAI,and a few here have done that,but it may be simpler to pay a bit more,and take the benefit of someone else's work in putting together a working system.
The current best are ITG,Revo and AMD.

 

[Jembo]

Experience of these on a standard car (MK2 16v golf GTi, MR2, Z4,... and a 2.0 TDi A3 which was remapped) was I didn't really notice any difference, whereas cooling the air to make it more dense as mentioned above reaps better rewards.

I've also heard that the filter must be dried properly, after cleaning otherwise the fluids can damage the combustion system - good luck

 

[Charlie23]

 

[Flexiblemouse]

I found the stock BWA setup to be a little restrictive at remapped power levels. I reduced intake temps by modifying my air box, and a panel filter freed up about 5hp.

 

[TDI140]

My remappingguy said my revo intake was the best one hes ever had on a tfsi engine on the dyno and my car made really good stage2+ power said most carsaverage between 340-350bhp i made 360bhp on all 5 dyno runs with low intake temps too he was impressed i say if you want a cai go for revo one really good quality too