Mark P

A while ago, I bought a cone filter and connected it to a 3" piece of mandral bent tubing. I mated that to the inside of my RS4 airbox.

I logged MAF and found that the cone filter was flowing more air. Great!

Or so I thought...

Later I became suspicious that the connection of the cone filter to the airbox was somehow altering the flow of the air and causing the MAF to read incorrectly (or at least different from the normal box to which the tuning was designed for). When I had done my comparison logs back in the day, I didn't log A/F, so I didn't have data which would point out a possible discrepancy in the reported values.

Whenever I have done any beta testing of code, I have always put a stock RS4 box with OEM filter back in the car, just to be on the safe/cautious side.

I still had that stock RS4 box in last week (3/1) when I took some stockmode logs of my car. This past weekend, I put my conefilter back in, and today (3/9) I took another set of stockmode logs. I wished I would have done all of this on the same day, as the temp was 20 degrees different, but I think the results are much more extreme that what would be caused by the temp difference.

Hopefully this weekend I will get some back to back logs done with both airboxes (in both stockmode and stg3 mode). Until then, I wanted to share the data I have gathered thus far....

Below you will notice that all runs have the same amount of boost. The conefilter runs, however, report higher MAF readings. I suspect these are incorrectly high. The code is trying to achieve about the same A/F, so it then adds more fuel with the conefilter runs in order to match the additional air that it believes it is getting (which it's not if the MAF is incorrectly high). This added fuel then results in a richer A/F mix which can be easily observed in the O2 Voltages.

The richer mix seems to slow down the acceleration/FATS as well.

I believe that the temp difference is causing the difference in timing, which is not directly related to the different MAF readings. This is one of the reasons why I want to log on the same day in the same temp to remove this variable.

I imagine that if the connection between my tubing and the MAF was smoother/flush, this wouldn't be such an issue. Nonetheless, I just wanted others to be aware of what I am observing...



<font color="red">Reds: apr stg3 tbox stockmode, cone filter, 37F, 3/9/06</font>
<font color="blue">Blues: apr stg3 tbox stockmode, rs4 airbox, 17F, 3/1/06</font>


<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image001 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image002 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image003 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image004 .gif">

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<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image006 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image007 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image008 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image009 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image010 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image011 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image012 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image013 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image014 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image015 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image016 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image017 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image018 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image019 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image020 .gif">

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<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image023 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image024 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image025 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image026 .gif">

<img src="http://ctny.audiworld.com/mark/s4/misc_data/logs/apr_stg3_tbox_mark_stockmode_stockfilter_vs_cone/index_files/Typical-3-9-2006_8-13-53_AM_stockmode_stockfilter_vs_cone_20814_image027 .gif">


<img src="http://ctny.audiworld.com/mark/s4/airboxmods/dsc05817.jpg">

Mark P

There was a nice red NSX that I had to be on guard for, so I changed modes. Nothing ever came of the NSX, but I had some fun on the way home. I put it back to stock mode until I confirm the exhaust rubbing this weekend. WOW, just WOW!

Imolavirus@BuehnEngineering

when using a larger MAF on a smaller airbox without a smooth transition between the two? I saw inflated MAF numbers when using the 83mm MAF without modifying the stock airbox enough so there was a step from the box to the MAF. After switching to the RS4 box MAF numbers went down slightly but performance went up. I'm guessing vortices causing an abnormally high MAF reading due to the step.

I'm wondering what would happen if we moved the MAF sensor further down stream.

Christian (Stage Ow)

Interesting findings, Mark. How would you "smooth" the connection? Logs look smooth, btw.

spt@lubzu

what if you put a screen to straighten the flow after the step?

Imolavirus@BuehnEngineering

i just removed the step and don't have the restriction of a screen

spt@lubzu

thats why u get the big bucks

Captain Matt, I be

i know a couple WRX/STI setups that do it that way, not sure if its possible with our setups.

Imolavirus@BuehnEngineering

so after the turbo somewhere?

Captain Matt, I be

yup.