Air filter mods:

[Koolvin]

I ordered a performance air filter from www.greenfilters.com  these are supposed to be

K&N beaters!!!

Cost? £40. The package arrived next day.

 

 

As usual I rapped the outer packaging to reveal this goodie inside!!

 

 

Yes it's Greeeeeeen! bogey coloured! the reason? so you can easily Identify when it is dirty!

 

 

Look at this shiney sticker you get!!

 

 

Instructions in german &nbsp; <img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/sad.gif" border="0" valign="absmiddle" alt=''> but go to their website and they have them (not like you need them)

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Yes they come pre-oiled and can be cleaned to use over and over..

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My Air box of my W202....

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Unplug the clips to see the filter....

See the Height difference? WOW!!

Bung the new one in! yes its a nice fit!

PUKE at old filter!

Conclusion? its like giving the car an Inhalr after having a asthma attack! after 2.5K revs it feels much 'Crispy' Highly reccomended! I give it the BiT-Tech Highly reccomended award!

 

[Malc]

Koolvin

Any idea how much increase in power you will get?

 

[Koolvin]

Im not sure in BHP as I have no Dyno machines, But you will notice the Accelerator more responsive and pickup and mid-range much much better

 

[Malc]

Thanks. I'll give it a go.

 

[Shude]

I fitted a green cotton air filter to mine too, it made a slight difference. &nbsp;The engine sounds a little better, 230k engines can sound a little &quot;strained&quot; when under a lot of load and this change sweetened the sound up nicely. &nbsp;I think it pulls a tiny bit harder too, some people claim it can add up to 10% more power on cars with forced induction, up to 5% on NA cars.

 

[Malc]

Didn't get round to it before, but thinking about it again now. Koolvin, are you still happy with your Green Cotton? Does anyone have experience of both these and K&amp;N?

 

[Dave B]

I've used both in the past and found there's little between them.  They both increase airflow over the original paper filters and will require cleaning and oiling after 50K miles...or something like that.  

Don't expect too much in the way of improved performance due to the constraints of the original air box and ducting - but it'll certainly help the engine to breathe more efficiently etc.

I recall Shude had some reservations about K&amp;Ns (something to do with the oil...yes?), but as they both require lubricant I'm not so sure it's an issue.

 

[djcheung]

I have tried a few suppliers but they don't do the filter for my 98' E240 petrol. Any ideas?
By the way, the link www.greenfilters.com does not work.

 

[Paul]

Tried link it worked for me <img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=''> .

But my E-Class is not on the fitment list either <img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/mad.gif" border="0" valign="absmiddle" alt=':angry:'>

Just out of interest I suppose the ECU would adjust the mixture accordingly to compensate for the extra air passing over the sensors, and increase fuel intake to keep correct mixture?

Pooped in to Halfords today and I noticed they sell these filters as well.

 

[Maverick]

hello,
what about the conic K&N filter, the one that u install instead of

the whole filter box, it's just a conic shaped filter, do u suggest

it ? they say it gives a great sound, but i don't think i would like

to get all the trash into my engine !! does it filter well or not ??

does it add good power as ppl say ??


thanx.

 

[Koolvin]

Originally posted by Maverick
hello,
what about the conic K&N filter, the one that u install instead of

the whole filter box, it's just a conic shaped filter, do u suggest

it ? they say it gives a great sound, but i don't think i would like

to get all the trash into my engine !! does it filter well or not ??

does it add good power as ppl say ??


thanx.

I'm not sure about the conical one, what I do know is that there is alot of heat under our hoods and that's not a good thing, you could end up loosing power unless it is mounted with a big heat shield and has some kind of air scoop from the front of the engine.. some people have been known to moubnt the filters behind their bumpers but what about all the debris and rain!! I say stick to your original airbox and maybee upgrade the filter element if you so wish.....


On my turbo kit I have a K&N filter but it has a housing purpose built....

 

[GaryC]

Yes. I agree, conic filter might not be prefect for all rpm range and temperature.

The efficiency of the engine, also rely on the inlet air temperature, the lower the inlet air temperature, the air could have more density, so, more oxygen.

If u want to install a conic filter, try to cover it up, just like the Piper cross one, with heat shield, and a duct, so, inlet air could directly suck from ouside, rather then the hot air under the bonnet.

It did improve the breathing of the engine, by remove the restriction of the air box and orginal filter.

But other factor which affect the preformance of the engine, is the TURBULENT.

More turbulent, enhance the air/fuel mixing, and the flame speed inside the combustion chamber (Cylinder). If the air flow with higher speed, more turbulent could be generated, so mjore efficient combustion, so, more power.

Inside the pipe/duct, if the size is smaller, the flow speed must be faster, (I can show the calculation, if you want...), so more turbulent.

For the conic filter, it did improve the top end breathing for the engine, because in high speed, it have enough turbulent already, so u could normally see the bhp has been improved.

BUT FOR LOW SPEED, if you remove the air box, to improve the breathing, turbulent generation might not be enough, hence the low end torque will be poorer.

So we have to decide whether we want more torque in low end, or bhp at the upped end.

Hope this could help...

 

[Sp!ke]

Originally posted by GaryC
So we have to decide whether we want more torque in low end, or bhp at the upped end.

.............unless you get a bit clever and go 'RAM AIR'

 

[GaryC]

Yes, It did have some improvement, but have to see whether the relatiionship between mass air flow rate in the low end and the pipe side of the inlet after the filter.

Because the Turbulent and Eddy current also generated in the pipe from the Grill to the orginal air box. Normally it must have some improvement, just see what engine is it.

The things I mention in my previous message, is exactly same as the principle of the Vtec system. It use a smaller cam shaft to open the Value will smaller opening at low speed, then bigger in the mid speed, and biggest in top end.

To generatee the flow velocity reach the certain level, in different engine speed, so as to generate enough turbulent, to improve all round efficiency.

Have anyone try to install a bigger and fatter cam shaft? and have you feel the poor engine torque in the low end? and that is the reason, of poor turbulent generation in low inlet air flow velocity.

 

[Mark300SL]

Sorry lads - just a short reply to this one - I have to do some work today !


Turbulence is only really desirable inside the combustion chamber, and is achieved by a combination of "squish" and the Venturi effect from the head inwards - this doesnt come into play until the inlet air charge is about to enter the cylinder head

The area just above the valve (including the exhaust) should be about 90% the size of the valve head, ie, if the valve is 30mm diameter, then about 3mm above the valve seat should be 27mm in size. This is the optimum for the venturi effect the inlet port needs. The port in this area should be as straight as possible for as long as possible, ie, you want at least 12mm or so (on the 'bottom' of the port) before the port turns into the direction of the inlet manifold. This is why engineers spend hundreds of thousands developing long injection trumpets to obtain the optimum inlet tract length.
Once finally in the combustion chamber, the air needs to be agitated to create the required turbulence, (but not by having to go over domed pistons).
The best shape chamber is one that has the inlet and exhaust valve at a shallow angle to each other. To aid combustion turbulence engine designers create a "squish area"

A 'squish area' is a part of the combustion shamber that is made to very nearly come into contact with the piston when the piston is at top dead centre. There's usually less than 0.020" (0.5mm) clearance in these areas in such cases. What they do is cause the combusting gasses to rapidly travel towards the centre of the combustion chamber (or where-ever the design engineer intended) and increase turbulence, thus increasing the combustion rate.

In regard to filters - I have an HKS filter fitted to my Rover turbo - this is on the end of as long and straight a picec of Samco that I could fit into the engine bay !

I currently have a cardboard template for a cold air box which I am designing , this will scoop cold air from beneath the car and the original cold air entry to feed air to the filter - and protect it from underbonnet temperatures as much as possible.


In Summary - Cold dense air is ideal for combustion - but it should be delivered in as smooth a stream as possible to the point where the head geometry takes over to create the required combustion turbulence, External turbulence is unnecessary and possibly undesireable- as it can reduce the mass of air that actually reaches the engine.

all IMHO of course

Mark

Back to work !!

 

[GrahamC230K]

I knew you would be posting in this thread any time soon!

 

[V12]

just about understood that.
All basic physics really, just a lot of logical thinking needed!!

I'd love to try out some real world testing one day...

 

[GaryC]

External turbulence is unnecessary and possibly undesireable- as it can reduce the mass of air that actually reaches the engine.

Laminar flow could reduce drag and friction in the flow within the boundary layer, in theory it will be better than the turbulent flow.

But, in fact, better air fuel mixing in the premixed charge has been proven in the turbulent flow.

You could not get away with the turbulent flow in the inlet manifold and the inlet pipe. the turbulent generation is depend on the air folw velocity, we could use the Reynolds number to determine, when will the turbulent generation be happen inside the pipe.

Re = density x velocity x diameter
------------------------------------
viscosity

where:
density = inlet air, suppose is constant
diameter = your inlet pipe diameter
velocity = your inlet air velocity
viscosity = your inlet air viscosity, suppose constant

ok, now the Re is depend on the variable of diameter of the pipe, and the velocity of the flow.

To determind when will the turbulent be generate inside the pipe, we have to see the manitude of the Re

normally, for Re < 2000, is Laminar flow,
for Re about 2000 to 4000, is the transition zone,
Re > 5000 is the Turbulent flow.

The flow velocity is depend on the pipe side

as the mass flow rate = density x pipr area x velocity


hence the rpm of your engine. So in high engine speed, the flow inside your inlet manifold and pipe was high enough to be turbulent flow, unless your inlet pipe and manifold is about 150mm in diameter!

We could do a very simple experiment at home, by using your water tap, suppose your water tap without any filter or any mesh on the nozzle, and the valve to outlet distance is long enough, so the valve will not interference the water flow, best way is to remove the shower head of the shower, and just use that pipe.

If we slowly turn on the tap, you could see the water pattern is straight, but as we increase the flow rate by adjust the tap, u could notice the flow become turbulent, the water patterns will swirl out from the pipe outlet and leave a swirl tonado like screw pattern in the water.

This is the optimum for the venturi effect the inlet port needs. The port in this area should be as straight as possible for as long as possible

Yes the port in that area should be as straight as possible, in theory, every part of the flow has to be as straight as possible, to reduce fictional losses, heat transfer, and pressure losses.

Also has to be without any contraction and diffusion section, in the diffusion nozzle, as the flow velosity suddently reduce (beacsue area increase), back pressure will be created, until the flow velocity reach a certain critical value, the nozzle will 'chock', and flwo will be restricted. That is rely on the topic about Compressible flow, in Fluid dynamic.

Anyway, whatever u want to keep your flow as straight as possible, there are one component which u can't ignore, which give the pumping loss to your engine, that is your throttle! that's the reason why the diesel engine has higher fuel economy, as the Basic Diesel engine run unthrottle, so the power control is by varying the quantity of fuel injected per cycle rather than by varying the density of the premixed charge; this reduce the pumping losses, and improve the fuel economy for it.

Once finally in the combustion chamber, the air needs to be agitated to create the required turbulence, (but not by having to go over domed pistons).

Yes that is ture, when the premixed charge reach the combustion chamber, it needs to create enough turbulent, but the charge turbulence in and entering the combustion chamber is create by the high flow velocity which depdnd on the valve opening area; the swirl around an axis normal to the cylinder axis is the most effective way, which known as the Barrel swirl. Not Squish.

When the compression strock start, the speed of the turbulent will be increase, and the temperature of the gases will increase as well, until the top dead centre, when the fuel ignite, the flame will transmit to the other area, which haven't ignite by the spark, by diffusion burning.

The faster the diffusion burning rate is, the higher the power and efficieny the engine will be, but how could we increase the flame speed? is by the help of turbulence inside the chamber; turbulence will multiplies the flame speed serval times, compare with the quiescent charge.

Small scale turbulence control the flame speed; the shape of the combustion chamber and the position of the spark plug determine the volume of charge consumed in sucessive increments of flame travel. Ideally, the constant rate of pressure rise with time is sought, and to achieve this, the area of the flame should diminish as it proceeds, to counteract the increase in unburnt charge density.

And you are ture, turbulence could generate in the addition of the squish zone, but most turbulence is generated by the inflow of the charge around the inlet valve.

I afraid the message is too long, if any information about thermo-fluid is require, please send message to the board,

Anyway, Mark 300SL, many many thanks for your reply , the discussion with you here is very very intresting, just bring the classroom back home with me from the uni!

You have great knowlege and experience in car mod, the only things I have about mod car is the bloody moded Cavaliver, and many theory and reserch in my head....

 

[Mark300SL]

T.B.C

On friday when I am sober


Mark

 

[amdxp]

I got my Green Filter yesterday !! :bannana:

Yeap, it help quite a bit in the mid range pull off, since the poor C180 is weak in low-end torgue.

I read the instruction that it requires to be washed every 5000-7000km ? AND we need to get the Green OIL and Green Cleaner, any other substitute ?