Interesting.......veeeerrrry interesting

[MCB]

S4TAN this was a really interesting post and the fact that you are not in a position to validate any results you have achieved I’m sure to the general audience does not matter at all (Also not implying that anyone here necessarily thinks you should either). For those that need more as you say they can check out AW.

You are a bit like me when it comes to VAGCOM will get there one day.

Keep up the good work, even a small improvement is moving in the right direction

[S4TAN]

Thanks MCB - i thought it was an interesting little mod too - so i thought i'd post it on the forum for all to consider

[neckarsulm]

Nice one S4TAN, I think seat of pants is OK if you know your car well.

My mechanic has prepared VR6 racing cars and removing screen from MAF is a widely accepted tweak which I think he said offers more torque.

I have VAG COM (dongled cable) and have seen many people with ebay purchased cables that dont work - I think Ross Tech are clever enough to restrict their use.

What's worse - paying a hard working software company which has reduced the stealers monopoly on diagnostics or paying a stealer £60 each time for them to spend 1 minute reading a fault code?!

Would do tweak myself and supply logs but only had car days and it needs EGT sensor.

[S4TAN]

I think seat of pants is OK if you know your car well.

Doing the mileage that i do i feel pretty 'connected' to my car and know it pretty well...(and can tell when something is different so I tend to trust my arse-dyno)

My mechanic has prepared VR6 racing cars and removing screen from MAF is a widely accepted tweak which I think he said offers more torque.

Cool - that's good affirmation

[MarkB]

FOD screen removal is now on my list of to do's...

[S4TAN]

FOD screen removal is now on my list of to do's...

FYI - I had to snip mine out with small cutters from the back as i couldn't pop my flow straightener out (for fear of damaging it) - fiddly but easily do-able.

My K&N panel filter has a wire mesh on both the clean and dirty side so i fully trust that to stop any foriegn object damage.

[h8cak]

I will be doing this tonight. I have had the Flow straightener out before so i will be going down this route

[UKS4APR1]

Just my 2p's worth following this subject, backing up S4woody and S4TAN...................
increase the pressure at the face of the turbos and they don't have to work as hard to make the requested boost, which means that the charge air is going to be cooler (More DENSE) because the turbo is working in a better efficiency island.

Comments Dr-Al ?

[S4TAN]

Comments Dr-Al ?

LMAO

[Dr-Al]

Just my 2p's worth following this subject, backing up S4woody and S4TAN...................
increase the pressure at the face of the turbos and they don't have to work as hard to make the requested boost, which means that the charge air is going to be cooler (More DENSE) because the turbo is working in a better efficiency island.

Comments Dr-Al ?

It may seem that way, but it's not as simple as that.

The process that results in a gas heating up when compressed is called adiabatic compression. The opposite of this is adiabatic expansion. Not surprisingly, if a gas is subjected to adiabatic expansion, it cools down.

If the turbos are sucking air against a slight restriction, there will be a pressure drop in the zone between the restriction and the turbo. As the air passes from the atmosphere (at atmospheric pressure) through the restriction, the turbo pumping out the air causes a pressure drop and the air cools down. Once it passes the turbos it is compressed, so it heats up again. The intercoolers are there to take away as much of this heat as possible before passing the charge air to the engine.

So, having a restriction does not necessarily increase the charge air temp, since the restriction will create a cooler intake to the turbo.

HOWEVER - the amount of heat energy the air absorbs from its surroundings is dependent on the difference in the temperature, so cooler, expanded pre-turbo air will pick up more heat energy from the pipework than air that has not been cooled by expansion.

I have to qualify all of this with the comment that, unless the restriction is severe (causing a significant vacuum pre turbo), both of these effects are TINY and you would need a very accurate thermometer to measure them.


That's not to say that there is no benefit from removing the restriction. The main benefit of any mod that removes airflow restriction is that the engine can get more air without having to expend energy to do so.

Think of going for a jog. OK, I know, it's not a pleasant thought, but bear with me. You might start out slow and you could get away with breathing through your nose only. You might be able to keep this up for a bit if you are taking it easy. This is equivalent to pootling along off boost.

However, if you step up the pace your muscle cells will require a higher flow of oxygen to function. Your autonomic nervous system (ECU) detects the increased oxygen consumption and calls for more air. This results in faster breathing. This is like the engine calling for more air/boost when you put your foot down.

Now, if you have anything that restricts the air coming into (and out of) your lungs (like gaffer tape over your mouth), then this will prevent them from extracting the oxygen needed to sustain the pace you have set, so you have to slow down. Similarly, if the engine cannot get the air it needs for a particular load, then it cannot put out as much power as it should.

For this reason, restrictions in the intake of a NA engine can spell death for the performance. However, turbocharged engines have the luxury of being force fed the air required. Kind of like running with pure oxygen being piped up your nose. This does not mean that they are immune to the effects of intake restriction, but they are less adversely affected by it.

If a turbocharged car has a restricted intake, then the turbos will have to work (expend energy) against the restriction to supply the air required. The energy used doing this work has to come from somewhere. It comes from the kinetic energy of the exhaust gases passing through the turbo. If you take more kinetic energy from the exhaust gas, then you slow it down more. This results in greater back pressure at the exhaust manifold, making it harder for the car to 'breathe out', thus reducing the car's power output

Hope this makes sense.

[UKS4APR1]

More fuel for the fire..... "conclusive proof"............. ??

http://forums.audiworld.com/s4/msgs/1029860.phtml

[S4TAN]

It may seem that way, but it's not as simple as that.

The process that results.........lots of physics........... power output

Hope this makes sense.

Doc - this is all well and good and even though i did my physics A-level 23 years ago i do understand the science in your post and it does make sense - but a judicious reading of your post reveals that, in essence, you are actually confirming that this is a beneficial mod to make! You could have saved yourself a lot of keyboard-tapping by just saying that in the first place! (however, I do enjoy your mini science-refreshers though)

[S4TAN]

More fuel for the fire..... "conclusive proof"............. ??

http://forums.audiworld.com/s4/msgs/1029860.phtml

quod erat demonstrandum...

[Dr-Al]

More fuel for the fire..... "conclusive proof"............. ??

http://forums.audiworld.com/s4/msgs/1029860.phtml

I'm sure this mod does have a benefit, but IMNSHO that graph does not add any evidence for or against.

1) The sample size for the 'with screen' data is much smaller than that for the 'without screen'. To validate a claim, both sample sets should be the same size

2) WTF is happening with the 'without MAF' data in the 3500-4500 range? It looks like the car is time-warping into the future the minute it hits 3500 rpm. When it rematerialises it is running at 4500 rpm.

It looks like dirty data to me.

[CliveH]

now I can understand the Latin, but not the science...