My question is: If the air box end of the PD 160 pipe is the same cross section as the std 130, which I assume it must be, how is it that the volume of air available to the engine increases. Go on, patronise me, I don't mind.

Without getting into a discussion about Venturi effects and volumetric flowrates, the ultimate amount of air that can enter the engine is dictated by the minimum cross-sectional area of the pipe. As you can see in this thread, the PD130 intake actually flares out at the filter end, whereas the the PD160 intake tapers gradually from inlet end to filter end. AIUI, this acts a bit like the power limiter on a 125cc motorbike, inasmuch as the amount of air entering the engine restricts how high the engine can rev. I assume the cross-sectional area of the PD130 pipe matches the requirements on the PD engine in 130bhp tune (you should see the size of the pipe on SWMBO's MPi - it's about the size of a garden hose! ) so a more powerful engine would need more air (hence the PD160 pipe).

Having said this, I also believe (as do others on here) that my car +PD160 but -Dragon Box is better able to rev above 3750rpm. This would tie in with the analogy about the power limiter, but I don't think anyone's proved or disproved any of the claims about the PD160 on its own.

Personally, I got mine to help reduce my exhaust being so smoky when the Dragon Box is on. Whether it was that, the injector cleaner, or the new air filter, I don't know - but at £75 a pop, I'm doing my best to convince myself it was worth it!

Theirs an old post somewhere were someone fitted a cupra intake pipe then went to jabba for a custom remap. I beleive Jabba were impressed with the results.

As for a std car. I cant see it making much difference. Well not to make it worth while for the cost.

Have you got a standard filter or an aftermarket one?

Thats one hell of an increase. Suddenly £70 seems not so expensive - even if it is just a piece if plastic pipe.

BTW did u know the figures before you added the pd160 intake?

standard filter,but don't go buying one thinking you will get that sort of increase,i noticed no real difference after fitting,wonder if i put on the pipercross filter i have in the boot i may get a little more;)that was the first time tess had been on the rollers,but i would suspect the figures would have been the same,it does feel like it breaths better top end tho

I'm running a standard filter and a revo, and the car used to smoke like a bitch. fitted the 160 intake and it smokes loads (and I mean loads) less. Power wise maybe there's a negligable difference, but it's certainly cleaner to drive around now.

Does fitting a PD160 intake invalidate your warranty?

All modifications invalidate your warranty technically.

The 160 intake looks stock though, because i suppose 'technically' it is! It is a VAG manufactured part afterall. The 160 probably comes out of the same factory as the 130.

You would probably find that the dealer wouldn't even notice. If it worried you then just put the original back on before having any work done.

You would probably find that the dealer wouldn't even notice. If it worried you then just put the original back on before having any work done.

Not sure about the dealer not noticing, as the PD160 intake is so broad it fouls the battery cover clips. Having said this, some dealers are mod-friendly, and after all you could indeed just pop the PD130 intake back on for service if you were worried about anything. Unlike a remap, etc. there shouldn't be anything recorded on the ECU to give it away, and as the gains in terms of power output are at best very small, it's hardly going to mash your clutch or anything. Seeing how they're £75 these days, though, I'd only consider one if you'd had something done to the engine (i.e a tuning box) that made it dead smoky (they seem to make quite a difference on that front) in which case the intake would be the least of your worries!

Can i use this analogy >

Debbie does Dallas could suck a golf ball through a straw....Perhaps, but a hose pipe definitely.

Can i use this analogy >

Debbie does Dallas could suck a golf ball through a straw....Perhaps, but a hose pipe definitely.

The way I see the question would mean 'Could she suck it through a straw attached to the end of the hosepipe?' As regardless of whether it's a larger diameter at the start it's the same size hole at the end.

Good point above. We need a scientist on here not a porn watcher.

Damn. Wrong career. again.

As regardless of whether it's a larger diameter at the start it's the same size hole at the end.

Whilst correct, the maximum air flow is limited by the narrowest cross section of the entire air filtering system. In the case of PD130 intake its the pipe, whereas with the PD160 its the connection into the air box. Therefore quite clearly the PD160 pipe has a higher mass air flow rate.

The question is, does the standard PD130 intake reach its maximum air flow during operation?

As the compression ratio remains the same, and the maximum revs remain the same, surely it won't make any difference. Unless of course the PD130 is restrictive to begin with. And as many people have mentioned fitting the PD160 reduces smoke and frees up the top end, proving that the standard PD130 is restrictive...

*I think* its not the actual surface area, but the material used in the filter...Its less dense than standard, so the air moves through it more freely. Imagine breathing through a piece of thickmaterial - it makes it harder. Now try it with a thin piece - much easier.

*sits and waits to be shot down in flames*

*I think* its not the actual surface area, but the material used in the filter...Its less dense than standard, so the air moves through it more freely. Imagine breathing through a piece of thickmaterial - it makes it harder. Now try it with a thin piece - much easier.

*sits and waits to be shot down in flames*

Correct! But we weren't talking about filters just the pipe

But remember a 'better' air flow through a filter will reduce its ability to filter the air, make the mesh too large and particles of dirt will get through, equally too small and the engine will suffocate.

The filter thing's part of it for sure. And it's not just what it's like to begin with, it's how it behaves once it starts getting dirty. My experience with cotton filters in industry is that they're actually pretty rubbish in the first few hours of use, as they need to get a bit cacked-up before they filter correctly. From the airflow point of view, therefore, fresh cotton filters are great! But from the filtration point of view, not so.

Now according to my copy of Perry's, a 1 sq.ft. drill cotton filter has a permeability of 300 cu.ft./min., whereas a 1 sq.ft. HEPA filter (the closest thing to a paper filter used in industry) has permeability of 125 cu.ft./min. This would suggest a cotton filter is considerably better in terms of letting more air across it, but then that's only really an issue if the airflow into the engine is anything like that amount. I imagine the size of the filter won't be much larger than necessary as anything too big would just be a waste of precious space (and under the bonnet of the Fabia vRS, space is very precious indeed!) IME, the filters are the same for all versions of the Fabia (for example), in which case the higher-output engines may well be pushing the filter's permeability to the limit. Then again, I can't imagine they'd design a car with a filter that wasn't able to supply enough air to the engine. OTOH, the thing with the intake sizes is that the PD130 has a definite 'neck' before the air reaches the filter box, whereas the PD160 funnels down to its narrowest point where it meets the filter box. There are various clever nozzle effects that could be used to improve airflow, but AIUI, the smoother (more laminar) the airflow through the filter, the better. The same volume of air travelling through a wider tube will have a slower velocity, and thus be less turbulent / more laminar.

So maybe both the filter and the intake make a difference, or maybe they don't. I've no idea where this post is going, so you can, er, draw your own conclusions...

I imagine the air flow will be pretty turbulent with either pipe, what with the engine sucking air in, air being forced in (from movement of the vehicle), ridges in air pipe, the intake being behind a grill etcetc. One less so than the other, probably, does makes a difference...

However I have read that cotton filters produce a less turbulent air flow than paper filters, admittedly this was on a 'performance' filter website

Whilst correct, the maximum air flow is limited by the narrowest cross section of the entire air filtering system. In the case of PD130 intake its the pipe, whereas with the PD160 its the connection into the air box. Therefore quite clearly the PD160 pipe has a higher mass air flow rate.

There doesn't really look that much in it between the diameter of the pipe and the air box end? And if the diameter idea was 100% true, then there would be absolutely no point in making a pipe larger than the airbox connection in diameter, which they obviously have done with the PD160?

Trouble with that pic is that it only shows the pipes in two dimensions. For example, it doesn't show that the filter box end of the intake isn't circular - it's squared-off, and a bit deeper vertically than horizontally. The ribbed section of the PD130 pipe is more-or-less circular, and is definitely narrower overall than the filter box end. The PD160 pipe is much broader horizontally, but not much deeper than the PD130 pipe. Overall, I imagine the cross-sectional area only reduces slightly from one end to the other (except for the trumpet of course!)

As regards having anything wider than the filter box inlet, a degree of tapering is useful to counter the pressure drop due to friction with the sides of the pipe (the narrowing of the pipe causes a degree of compression, which helps maintain air velocity). In fact, AIUI, the wider the intake, the better up to a point. But speaking from experience, the PD160 pipe really does take up all of the available room between the engine and the battery, so short of fitting a cone filter or induction kit of some sort, I don't think there's any way to increase it!

There doesn't really look that much in it between the diameter of the pipe and the air box end? And if the diameter idea was 100% true, then there would be absolutely no point in making a pipe larger than the airbox connection in diameter, which they obviously have done with the PD160?

Cross-sectional area not diameter. I also agree with ap0gee regarding the tapering effect. Although I'm not entirely sure in this example, as the engine is sucking air into the airbox, rather than it being forced into the airbox.

And as to there being no point, of course theres a point, Seat are selling a £2 pipe for £75. That genius!

It's along time since I studied fluid mechanics at uni, but AFAIR flow not merely a direct function of the smallest area of the pipe. It is also a function of the drag per unit length - which will also be a function of area (per unit length).

I need to lie down now - the words "Bernuli equation" just flashed across my conciousness! Of course it was a long, long time ago now and I was frequently very, very drunk so I may be talking bullsh1t!

has the price gone up due to us lot buying them?

has the price gone up due to us lot buying them?

Pretty much, yep!

so carbon re-makes then?

Just read this info and I have to say, I'm very interested. I thought the mighty vrs was adequate enough but of late, I'm now used to it! My mate got the increased air intake and it put his BHP and torque up. My question is this - being stupid, lazy and in no way technically minded, where can I lay my hands on one of these lovelies??? What is the part number???