MAF Screen or No-Screen? Preliminary results inside...
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2004-2007 Cadillac CTS-V General Discussion Discussion, MAF Screen or No-Screen? Preliminary results inside... in Cadillac CTS-V Series Forum - 2004 - 2007; Tested the MAF screen removal today: Results of no screen: AFR leaned out an average of nearly four tenths at ...
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    StealthV's Avatar
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    MAF Screen or No-Screen? Preliminary results inside...

    Tested the MAF screen removal today:

    Results of no screen:
    AFR leaned out an average of nearly four tenths at WOT
    Lost an average of 1.1 hp from 2000 rpm to 6800.
    MAF measured air flow was 3.2% less (hence the leaning out of the AFR)
    Measured asphalt performance from 29 to 98 mph = 0.151 seconds slower

    Test Conditions:
    Screened IAT = 77.8*F
    Descreened IAT = 76.4*F
    Screened ECT = 192*F
    Descreened ECT = 192*F


    On a stock tune, leaning out the AFR @ WOT would be a good thing. Since my WOT AFR was already dialed in with the MAF screen in place, the more lean mixture without the screen hurt performance as noted above.

    Was collecting data to recalibrate the MAF for no screen and my laptop died midstream. Once the MAF is recalibrated for the measured reduced flow, the performance should be back to screened levels if not more.

    Headed out for calibration data now.....

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    So, you feel that you can increase perf. w/o the screen once you compensate the tune?

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Once the MAF is recalibrated, the performace should be at the minimum the same as it was screened. Whether it'll actually pick up anything - that remains to be validated.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Got round two of testing done today. The descreened MAF and its ability to measure the air flowing past it is off anywhere from 0 to 5% depending on the airflow required to feed the engine. Some interesting harmonics showed up in the data which will require a little more investigation. If the harmonics show up again, descreening a MAF without a corresponding tune adjustment would cause flat spots and hesitation in acceleration along with incorrect fuel trims.

    At low airflow rates, the decreened MAF has trouble measuring the air going by as one would expect; through the middle frequency range, there isn't much difference between screened and and without. Up top, the descreened MAF starts to have trouble measuring the airflow again.

    Performance gain or loss from a properly calibrated descreened MAF is next; stay "tuned."

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Yep, sounds exactly like the problems associated with descreening a MAF... slight surging... hesitation... It's going to be tough to compensate with a tune... HMO of course.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Compensation in the tune is easy *if you know what you are doing* as it is already done.

    There are zero flat spots or hesitations on my descreened and now recalibrated MAF. In fact, I can't tell it is descreened other than the 1 oz. of honeycomb laying on the workbench. Need to get the performance testing done next as this is definitely not a SOTP detectable mod.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    So the question is, is de-screening worth it? It sounds like a miniscule gain is possible, but probably not more than I'd gain if I watched my diet for a few weeks and lost 5 pounds...

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    True, but it may help HDMLNIUM get to 12.8

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    FWIW, on the LS1 Fbody's it wasn't worth it. Neither was the bigger MAF's Granatelli etc. at least not on a basically stock motor. Bore it and stroke it and the rules change of course. I ran an auto Fbody and it took three things to put on of those in the 11's 150 shot of N20, 3500 RPM stall converter and drag slicks. 150 shot of N2O ought to put HDMLNIUM in mid 12's at least.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    a 150 shot would put him in the high 11s with traction.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Quote Originally Posted by c5racr1
    a 150 shot would put him in the high 11s with traction.


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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Don't a lot of aftermarket CAI's omit the screen and count on the new high flow filter element to “stratify” the air? For my ’04 Cobra K&N claims 30.8 HP at 5,900rpm, which I thought was ridiculous until I installed it and ran it—really made a noticeable everywhere in rpm range. You can really hear the Eaton blower now too. The car even starts more “aggressively”.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    On my '03 Cobra, I ran the K&N filtercharger kit too. It was my third CAI and the best, as the dyno showed. But you have to keep in mind that that kit included a mini velocity stack built into the filter mount. That had a HUGE effect on the airflow, and was the reason why the K&N bumped my rwhp from 424 to 451 hp (and that was over an upgraded open CAI, NOT the stock filter). Unreal bump for a CAI, and it wasn't really, it was a big bump from a well designed velocity stack.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    On the dyno for my car, we tried three MAF meters, a stock modified LS1 meter with composite ends,no screen. it worked ok, then we tried an actual Z06 piece/LS6 piece with no screen from the factory,...ran ok,...then we tried your guys CTS-V/6.0 liter(truck) screened MAF meter, which is the same as the Z06 piece but with a screen, which is what we have choosen to run on my car.

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    Re: MAF Screen or No-Screen? Preliminary results inside...

    Quote Originally Posted by ntechnic
    On my '03 Cobra, I ran the K&N filtercharger kit too. It was my third CAI and the best, as the dyno showed. But you have to keep in mind that that kit included a mini velocity stack built into the filter mount. That had a HUGE effect on the airflow, and was the reason why the K&N bumped my rwhp from 424 to 451 hp (and that was over an upgraded open CAI, NOT the stock filter). Unreal bump for a CAI, and it wasn't really, it was a big bump from a well designed velocity stack.
    Thank you for validating that. I noticed the velocity stack too--of course my Supra buddy tells me the imports have been doing that for many years.

    YOU DID NOT INSTALL THE SCREEN, RIGHT??

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