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pilchardthecat's MAF screen mod

After the initial datalogging of the Honeycomb MAF screen, I wanted to see what the ECU does to adjust to the increase in airflow which the Honeycomb screen allows, so I did some more datalogging looking at Ignition Timing and Equivalence Ratios. The Equivalence Ratio is equal to 1 when the Air Fuel Ratio is at the stoichiometric mix of 14.7:1, so when the AFR is at, say, 13:1, the Equivalenace Ratio is 0.88.

I've produced the graph below by first running the car with the Honeycomb MAF screen and then swapping back to the OEM MAF screen and then repeating the same runs.


ComaprisonOEMvHoneycombMAFscreen_zps2651e48f.jpg


As the graph shows, the engine acceleration is more linear at the upper RPMs and the airflow is higher at all stages of acceleration with the Honeycomb screen. The Equivalence ratios are very similar but with the Honeycomb screen the AFR might be at, say, 13.2:1, whereas in OEM it might be at 13:1 at the same RPM. Likewise, the timing is similar, except at the highest RPM with the Honeycomb screen, the timing advances as the redline is approached: this seems to smooth out the "stuttering" that normally appears at around 7300rpm. I have previously suggested that the dip in performance at around 7300rpm might be caused by resonant effects, specific to the Z4M's air-intake, but it would now appear that the problem is more likely to be caused by turbulent effects caused by the OEM MAF screen. I shall now look in more detail at individual parameters at 7000rpm and above to see if the MAF screen is the problem.
 
Very interesting, and entirely in keeping with my arse-dyno & theorising - it definitely feels like it breathes better at the upper part of the range.

I appreciate the time spent testing.
 
Is this a mod that works for the Z4M or could it be done on other models.


That graph is quite impressive for a mod that's straight forward and cheap to do.
 
pilchardthecat said:
Very interesting, and entirely in keeping with my arse-dyno & theorising - it definitely feels like it breathes better at the upper part of the range.

I appreciate the time spent testing.
Click to expand...

Same here at first seemed flat at low revs but now feels better across the rev range.
3.0 se .not 'M' but still fookin fast :grin:
Moz
Sent from my GT-I9300 using Tapatalk 2
 
Mark-Z4 said:
Is this a mod that works for the Z4M or could it be done on other models.


That graph is quite impressive for a mod that's straight forward and cheap to do.
Click to expand...
Try it and see :)

I haven't looked at the intake system for the other models, but i think some parts are common between the M and the 3.0
 
Mark-Z4 said:
Is this a mod that works for the Z4M or could it be done on other models.


That graph is quite impressive for a mod that's straight forward and cheap to do.
Click to expand...

If your air intake has a screen in front of the MAF like the Z4M (which I expect it does) then this mod will work for you. :thumbsup:

Below is a photo showing the OEM MAF screen of the Z4M on the left and on the right is a photo of the Honeycomb screen fitted in the air-filter box lid.

HoneycombMAFscreenphoto_zps67e95f93.jpg


The OEM Screen has both a plastic mesh and a wire mesh, where the thickness of the wire is 0.23mm and the plastic mesh is 0.43mm. There are 42 wires across the 87.1mm aperture of the MAF screen so the total thickness of wire across the screen is 9.66mm and there are 17 plastic wires, with a total width of 7.31mm: That's a total reduction in aperture width of (9.66mm + 7.31mm =) 16.97mm or 19.4%.

In comparison the honeycomb walls are 0.08mm thick and there are 28 cells across the maximum aperture of the MAF, this represents a total thickness of cell wall of (28 x 0.08 )+25% = 2.8mm or 3.2%. Clearly, the Honeycomb MAF screen impedes the flow of air less than the OEM MAF screen with the added advantage that it "straightens" the air as it flows past the MAF, giving more consistent readings from the MAF.
 
I fancy giving this a go for some cheap induction noise :)

Do you guys think a 0.5mm sheet will be about right?

http://www.ebay.co.uk/itm/3K-Carbon-Fibre-Rigid-Sheet-0-5mm-x-200mm-250mm-16-75-/151160534401?pt=UK_ToysGames_RadioControlled_JN&hash=item2331deb581
 
This kit also looks very interesting:

http://www.ebay.co.uk/itm/Carbon-Fibre-Fiber-Cloth-Skinning-Wrapping-Covering-Sheet-Kit-Real-NOT-Vinyl-/251373325126
 
Don't forget that the honeycomb will change the flow characteristics across the width of the intake. The MAF only measures airflow where its in the airflow, ie the centre of the intake, so don't assume that just because you're seeing an increase in airflow over the MAF you are necessarily getting more air into the engine.
 
Lower said:
Don't forget that the honeycomb will change the flow characteristics across the width of the intake. The MAF only measures airflow where its in the airflow, ie the centre of the intake, so don't assume that just because you're seeing an increase in airflow over the MAF you are necessarily getting more air into the engine.
Click to expand...
I agree with that point but my datalogging of other parameters shows that there is a performance increase which, to my mind, shows that the recorded increased flow through the MAF is genuine.
 
Guys,

Finally getting round to this, apologies if I've missed the answer in the above discussion, but do I need to trim the new MAF screen in terms of depth\thickness?

Where does it sit? In the con-caved section, or where I cut the mesh from? Should I fix\bond it somehow?





G
 
It's hard to explain how you should fit this, but the OEM plastic rim in your photo has to fit in exactly the same way with the honeycomb screen as does the OEM MAF screen. So you need to cut a rebate around the edge of the honeycomb screen. To do this, I stuck a few pieces of masking tape onto one face of the honeycomb and then traced around the plastic rim. I then used a Dremel with a diamond cutting disc to cut the circle marked on the masking tape to fit within the plastic rim, BUT I ONLY CUT about 5mm into the honeycomb I then cut from the side of the honeycomb just enough to remove the honeycomb to produce the rebate. Does this make sense?
 
Yeah I think so :-) I tried cutting it with thin tin cutters, but at the mercy of the honeycomb structure, so stopped, really hard to do it neatly. I wonder where my dremel is!!
 
gwatson said:
Yeah I think so :-) I tried cutting it with thin tin cutters, but at the mercy of the honeycomb structure, so stopped, really hard to do it neatly. I wonder where my dremel is!!
Click to expand...

The honeycomb is thin enough to cut with a pair of nail-scissors. Just don't tell your wife you've used them. :wink:
 
exdos said:
If your air intake has a screen in front of the MAF like the Z4M (which I expect it does) then this mod will work for you.
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Just a bit of a thread revival but would the honeycomb mod be worth doing on a 3.0 si that does not have a MAF screen or is the air flow across the sensor acceptable in this case ?

All comments welcome I won`t be offended :poke:
 
1536Z4 said:
Just a bit of a thread revival but would the honeycomb mod be worth doing on a 3.0 si that does not have a MAF screen or is the air flow across the sensor acceptable in this case ?

All comments welcome I won`t be offended :poke:
Click to expand...

If the OEM MAF of the 3.0si doesn't have a screen then don't place anything in front of it.
 
couchflyer said:
What do you use to secure the honeycomb to the OEM plastic ring with?
Thanks
Click to expand...

I presumed it would hold itself in place once you had cut the slot as on page 5 but otherwise I would think superglue or silicone sealant would be fine .
 
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