What does this bit inside the airbox do?

[07 vRS Taxi]

It would seem that in the process of removing said cover and replacing it this morning, my engine has lost some of its zing, my on-board organic gyro would indicate something in the region of 20 of Shark's finest horses, so *hopefully a dislodged pipe somewhere....

*hopefully as in this would be the least expensive diagnosis.

check that all four rubber bushes are seated in the back of the box otherwise its just gonna be sucking in warm air from the engine bay.

[vRS Carl]

Jonno - I took mine out when I put my ITG filter in. I did logs before and after on the Air Mass and there was no difference (or I should say negligible as no two runs are ever the same) so I wouldn't worry about it. My car has been like that for about 5k miles now with no issue.

With the OEM filter the depth of the filter holds that in place. If you have K&N/ITG/Piper etc it rattles about which is why I removed mine.

Either way it won't cause any issues.

[vRS Carl]

To remove TFSi covers the correct method is stand at the front of the car, looking at the engine start from the top right (nearest passenger) and work anti-clockwise so:

Top Right

Top Left (remember to disconnect MAF and clips to turbo)

Bottom Left

Bottom Right

A drop of oil on each bung afterwards will aid removal in future.

[stever750]

check that all four rubber bushes are seated in the back of the box otherwise its just gonna be sucking in warm air from the engine bay.

I know this sounds stupid, but how do I do that exactly? I didn't take it off, so am not at all familiar with how it is fitted.

[Chrispy]

faster flowing air is cooler therefore has a higher oxygen content, the process of increasing the oxygen content carrys on right up to the piston crown where it has another kind of swirl chamber.

Surely the oxygen content/ percentage is fixed based on the quality of the air you take in? Unless the car can change nitrogen/ CO2 whatever other gases come in into oxygen by the clever use of an airbox! Fast flowing cooler air is denser though and denser air is good - higher volumetric efficiency and cooler for the turbo which inevitably warms it up, hence intercoolers are fitted.

This is where water injection comes in too. Cools the charge and can make huge differences to power levels especially if combined with methanol.

[07 vRS Taxi]

Surely the oxygen content/ percentage is fixed based on the quality of the air you take in? Unless the car can change nitrogen/ CO2 whatever other gases come in into oxygen by the clever use of an airbox! Fast flowing cooler air is denser though and denser air is good - higher volumetric efficiency and cooler for the turbo which inevitably warms it up, hence intercoolers are fitted.

This is where water injection comes in too. Cools the charge and can make huge differences to power levels especially if combined with methanol.

Things can always get better with engineering the air intake has all kinds of angles,mesh,chamber to get the air 'fizzing' before it enters the combustion chamber. Your right about turbos they create high pressure and with that comes heat which reduces oxygen content thats why intercoolers are a must!

[Chrispy]

Things can always get better with engineering the air intake has all kinds of angles,mesh,chamber to get the air 'fizzing' before it enters the combustion chamber. Your right about turbos they create high pressure and with that comes heat which reduces oxygen content thats why intercoolers are a must!

I think you're confusing oxygen with general air which is a pre-determined mix based on what the car sucks in from the outside world. What comes out of the exhaust is a different matter altogether as that has undergone a reaction through combustion, hence we have EGR and catalysts etc so the stuff that finally comes out of the tailpipe is low in things like NOx and CO. Oxygen is used through combustion along with hydrocarbons (petrol/ diesel) to produce water, CO2, NOx, CO and a few other bits and bobs.

Normal air is around 21% oxygen and this % does not change regardless of how warm or cool it is. However, how dense the 'air' is (as in all of it, all the gases in the mix) does change - the cooler, the more dense. This is why cars, especially turbo'd ones run better in cold damp weather as the charge is cooler on the way in, thus more dense and therefore more of it is going in. It also helps reduce turbo lag.

So a swirl chamber can improve torque by increasing air turbulance as it goes through the intake. This means there's actually less air going through but it's moving faster thus can be a smidgen cooler and help fuel atomisation.

Not sure if anyone remembers things like TVIS on old Toyota's (my MR2 had it) and even Twin Port on Vauxhalls. That was the idea here especially on 16v cars that were slightly less torquey in the lower rev bands than their 8v counterparts. Remember the old 8v 1.9 Pug engine? That was a torquey old thing but at the top end was a bit pants, thus the 2.0 16v came along for things like the ZX Volcane 16v, 405 MI16 blah blah blah. Manufacturers would try to vary the intake port size/ length to cater for low rev torque and high rev breathing. So at low revs some of the intake runners were closed to increase turbulence, air intake velocity and fuel atomisation. Then at higher revs (think it was about 5500 on the MR2) the intake runners (controlled by vacuum) would open fully and allow all the air in so the 16v head could breathe fully and rev it's nuts off.

[07 vRS Taxi]

All my posts are what I know to be fact, turbulant air does have a higher oxygen content. I have studied service and repair up to level 3.

Edited 9 May, 2012 by 07 vRS Taxi

[Chrispy]

All my posts are what I know to be fact, turbulant air does have a higher oxygen content. I have studied service and repair up to level 3.

I think I see what you're getting at and it's purely a wording thing hence I thought you were saying something else. Faster flowing air is denser thus will have more oxygen in it as there is more air overall.

The percentage of O2 in the mix related to the percentages of other gases will be the same, but as it's denser (cooler) there's more air overall thus more oxygen. Does that tally with your thinking?

[marcevo1]

Density and flow getting confused

Forced induction give high 'forced' flow and higher density of oxygen. Unfortunately the compressing causes heat... Which reduces the density....

Cooler the charge the more oxygen - more pressure = more heat and less oxygen

Any 'supercharging' above 5psi and the need of an intercooler is needed to make the pushing worthwhile (rule of thumb)

Hope that makes sense....

[marcevo1]

Not sure if anyone remembers things like TVIS on old Toyota's (my MR2 had it) and even Twin Port on Vauxhalls. That was the idea here especially on 16v cars that were slightly less torquey in the lower rev bands than their 8v counterparts. Remember the old 8v 1.9 Pug engine? That was a torquey old thing but at the top end was a bit pants, thus the 2.0 16v came along for things like the ZX Volcane 16v, 405 MI16 blah blah blah. Manufacturers would try to vary the intake port size/ length to cater for low rev torque and high rev breathing. So at low revs some of the intake runners were closed to increase turbulence, air intake velocity and fuel atomisation. Then at higher revs (think it was about 5500 on the MR2) the intake runners (controlled by vacuum) would open fully and allow all the air in so the 16v head could breathe fully and rev it's nuts off.

Variable inlet tract tuning

No so much turbulence really but volume and ram charging. Really complex and abnormalities on certain engines. Variable was an attempt to get added flexibility but a compromise (and sometimes a jerky transition).

8v v 16v debate.... Many an hour spent discussing the merits on this one... Be it mk2 golfs or Chevette rally cars nearly as long winded arguements on here about tdi tsi which is best!

Plenum flow and volume comes into play too...

[07 vRS Taxi]

I think I see what you're getting at and it's purely a wording thing hence I thought you were saying something else. Faster flowing air is denser thus will have more oxygen in it as there is more air overall.

The percentage of O2 in the mix related to the percentages of other gases will be the same, but as it's denser (cooler) there's more air overall thus more oxygen. Does that tally with your thinking?

you got it ;-) thats what I was saying air is bounced allover the place in order to 'shake it up'

[Chrispy]

you got it ;-) thats what I was saying air is bounced allover the place in order to 'shake it up'

[Chrispy]

Variable inlet tract tuning

No so much turbulence really but volume and ram charging. Really complex and abnormalities on certain engines. Variable was an attempt to get added flexibility but a compromise (and sometimes a jerky transition).

8v v 16v debate.... Many an hour spent discussing the merits on this one... Be it mk2 golfs or Chevette rally cars nearly as long winded arguements on here about tdi tsi which is best!

Plenum flow and volume comes into play too...

Agreed. TVIS transition on the MR2 was a sudden "shove" as it opened up the extra intake runners. And the 8v vs 16v discussion.....spend any time on a Golf MKII /MKIII GTi forum and that one is discussed to death.

[k.young]

Try getting at the air filter in a Beamer 320d and you might think the Octy is easy.

Sent from my HTC Sensation XE with Beats Audio Z715e using Tapatalk 2