I like to get my Vrs (petrol) to breath a bit better. I thought about changing the airfilter with a Performance one but is this worth doing? Or would it be better for me to safe the money and buy a full induction kit? The only reason why I'd buy the airfilter is of cost. The Induction kits are very expensive and i'm worried it might mess up the airflow sensor. Can anyone please give me an idea what is worth buying and what is not? I want a bit more power & sound.

I like to get my Vrs (petrol) to breath a bit better. I thought about changing the airfilter with a Performance one but is this worth doing? Or would it be better for me to safe the money and buy a full induction kit? The only reason why I'd buy the airfilter is of cost. The Induction kits are very expensive and i'm worried it might mess up the airflow sensor. Can anyone please give me an idea what is worth buying and what is not? I want a bit more power & sound.

Hi

Yes , I had a Pipercross one on my Fabia and gave a tad more acceleration , and a tad more fuel economy

Is your vRS a MK2 or MK1?

Dont expect alot from it , but will last alot longer than a standard one

http://www.awesome-gti.co.uk/section.php?xSec=991

These are so cheap , I just ran it for 60k miles then threw it

Alot of people will come on now and say its rubbish , but hey each to their own opinion

Mine it , it works , and at them prices , rather than listen to the doubters , try it for yourself

Ni it will not damage the MAF , they can kill themselves LOL

Sarah

Hi

Yes , I had a Pipercross one on my Fabia and gave a tad more acceleration , and a tad more fuel economy

Is your vRS a MK2 or MK1?

Dont expect alot from it , but will last alot longer than a standard one

http://www.awesome-gti.co.uk/section.php?xSec=991

These are so cheap , I just ran it for 60k miles then threw it

Alot of people will come on now and say its rubbish , but hey each to their own opinion

Mine it , it works , and at them prices , rather than listen to the doubters , try it for yourself

Ni it will not damage the MAF , they can kill themselves LOL

Sarah

Thanks Sarah!

My Octi VRS is a MK:2. I think I will buy the performance induction air filter as it will save me money in the long run when the normal one needs replacing. I used to have a K&N Induction pannel filter for my old Ford Escort and it claimed it would last 100k miles!!!! the filter that is, not the car! lol Cheers again!

I like to get my Vrs (petrol) to breath a bit better. I thought about changing the airfilter with a Performance one but is this worth doing? Or would it be better for me to safe the money and buy a full induction kit? The only reason why I'd buy the airfilter is of cost. The Induction kits are very expensive and i'm worried it might mess up the airflow sensor. Can anyone please give me an idea what is worth buying and what is not? I want a bit more power & sound.

Getting as colder air as possible to the engine via the air filter will improve performance and help it breathe better too. Have a looksie around for cold air mod.

and see here:

http://briskoda.net/forums/topic/181301-airbox-mod-and-3-pipping/

Getting as colder air as possible to the engine via the air filter will improve performance and help it breathe better too. Have a looksie around for cold air mod.

and see here:

http://briskoda.net/forums/topic/181301-airbox-mod-and-3-pipping/

Which isn't that true of turbo engines, because the air is heated significantly by the compression, and then cooled again by the intercooler, which actually works better on hotter air!!

What I'd do, to establish the best baseline, is a Pipercross (as Sarah suggests, run it for a bit and then toss for a new one), which will give as much as a CAI will (and that's mostly better pickup rather than more power), and one of the various RH arch vent mods (swiss cheese, galvanised hut vent or proper Audi TT vent) to keep the intercooler in the coolest air possible.

The air entering the engine will contain more oxygen if cooler, even if this has passed through a turbo then the intercooler. Cooler air to the turbo will mean cooler air out of the turbo before it passes through the intercooler which will further cool the air down prior to entering the engine.

Better gains could be had with an uprated aftermarket intercooler, this is an expensive option though.

Have a looksie at this page:

http://www.dieselbob.co.uk/tuningmethods_plus.shtml

The air entering the engine will contain more oxygen if cooler

Ok, exactly how does temperature affect the chemical composiiton of the air? When answering, you might want to bear in mind that I have studied chemistry and fluid dynamics, even if I don't use them at work.

cold air is more dense so i would have thought the % of oxygen per same volume from warm to cold air would be different

Yeah cold air is more dense. So a larger quantity of cold air can occupy the same space as a lesser amount of hot air occupies. Therefore more oxygen molecules.

Colder dense air contains more oxygen molecules than hotter air.

If it's a MK2 Octavia a CAI is better than stock, especially if it is remapped as the standard airbox does not seem to flow the required air flow and boost does seem to drop @ top end. On the 1.8t I would say don't bother as there would be very little gain.

The proven intakes seem to be Evoms,ITG,BSH and Forge.

... the intercooler, which actually works better on hotter air!!

Sorry Ken, I'm going to have to pull you up on that one as well (It's quite a common misconception, though)

The rate of cooling depends on the difference between the object temperature and ambient temperature, so (I'm making these numbers up for simplicity) if air entering at 80^oC loses 40^oC in my theoretical intercooler, then air entering at 40^oC would only lose 20^oC in the same time. Because the hotter air is cooled by twice as much, a lot of people think it must be working better. However what comes out is air at 40^oC vs. air at 20^oC, so it's still a case of hotter in = hotter out. That's physics for ya!

Ok, exactly how does temperature affect the chemical composiiton of the air? When answering, you might want to bear in mind that I have studied chemistry and fluid dynamics, even if I don't use them at work.

??? am i going wrong somewhere?

Edited 24 February, 201115 yr by kenny

i take it i wasnt wrong then :wonder:

Nah, not wrong.

Was wondering if ken would reply

sorry guys, ken is right, the chemical composition of air doesn't magically change according to temperature. it still contains the same constituent parts, it's just that if the air is cooler it's more dense which in theory means a higher mass of air can be contained in a smaller space... but to be fair the effects from this are so maginal anyway

on the subject of 'performance' replacement filters i will remain a hardened cynic i'm afraid, a 1bhp 'gain' is not worth a hill of beans in real terms. i suppose the only real terms gain you get from them is the fact that if they are carefully cleaned and re-oiled they can be re-used time and again, but you have to weigh up the cost of the part compared to a big stack of standard oe filters

im not saying the composition changes but there will be more oxygen per cubic metre in dense cold air rather than warm air

That may be what you meant Kenny, but you did actually phrase it as saying that the proportion of oxygen in air changes with temperature, rather than the the density of air changes with temperature.

On the more general point of CAIs with turbo engines; has anyone ever actually proven that a CAI on a road car has an effect on the temperature of the air in the turbo to intercooler pipe?

on the subject of 'performance' replacement filters i will remain a hardened cynic i'm afraid, a 1bhp 'gain' is not worth a hill of beans in real terms. i suppose the only real terms gain you get from them is the fact that if they are carefully cleaned and re-oiled they can be re-used time and again, but you have to weigh up the cost of the part compared to a big stack of standard oe filters

You forgot the cost of your insurance premium as well

cold air is more dense so i would have thought the % of oxygen per same volume from warm to cold air would be different

hmmm not sure i did, others may have but im not going to be akward as i know what is and isnt right

Let's face it all this marketing performance filters is a load of bull lol

Runs and hides.

hmmm not sure i did, others may have but im not going to be akward as i know what is and isnt right

I had a re-read and you didn't say the chemical composition changes.

the resident chemistry and fluid guru must be seeing things.

as for CAI increasing BHP, cooling air into the turbo etc:

Post #3 http://dodgeforum.com/forum/neon-srt-4/10252-why-cai-on-a-turbo-car.html

http://www.jbsautodesigns.co.uk/product/905/cold-air-induction-kit

I had a re-read and you didn't say the chemical composition changes.

i must have read it wrong too then

another note on air density; the molecule of air changes shape with density, it arranges itself into the most energetically favourable position/shape hence why you can fit more air into the same space if it's colder, wether this affects the speed at which combustion can occur with a liquid fuel i don't know? i'd have to do some reading up on it again

another note on air density; the molecule of air changes shape with density, it arranges itself into the most energetically favourable position/shape hence why you can fit more air into the same space if it's colder, wether this affects the speed at which combustion can occur with a liquid fuel i don't know? i'd have to do some reading up on it again

And what exactly is a molecule of air? :p

Since I'm in a pedantic mood again, a few points: I don't believe diatomic oxygen (the ~21% of air that matters here) has much choice of what shape it is. Also gas density depends on the energy the molecules have and thus how fast they are moving - individual molecules are so far apart most of the time that their shape is pretty much immaterial. The only situation I can think of offhand where molecular shape affects density is the anomalous expansion of water (due to Van Der Waals forces on the water molecules which are slightly polarised because of their shape, IIRC), but then A-level chemistry was quite some time ago. The quality of combustion depends almost entirely on the distribution and mixing of the fuel in the cylinder - it's safe to assume the oxygen is just there.

Oh, and to get back on topic, as far as I'm aware the main benefit of oiled gauze filters is that they don't clog up the way paper/foam ones do, so in practice it's really more of an case of maintaining performance rather than adding it, despite what the manufacturers claim.