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descreen or not to descreen..

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Old 06-28-2005, 12:53 AM
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descreen or not to descreen..

I basically know what the MAF does but what's the purpose of that restrictive screen there. It has to do something so I'm wondering if that descreening mod will throw a code. I ready that this mod is worth another 180cfm thru the TB but at what cost? Thanks.
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Old 06-28-2005, 01:05 AM
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Re: descreen or not to descreen..

Y'know, when I first started coming to this site years ago - the word was to descreen it, and it seemed that everyone did.
Some even posted that as a "mod" in the their sigs.

It looks like the trend has reversed, people are saying to leave it in, that it does more harm than good - if it does any good at all.

It certinally doesn't give any seat of the pants feel when driving.

Although I decreened mine and have suffered no ill effects - I would say don't bother to your question.
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Old 06-28-2005, 08:37 AM
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Re: descreen or not to descreen..

You won't notice any benefit from descreening. Don't bother.
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Old 06-28-2005, 08:45 AM
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Re: descreen or not to descreen..

on a side not...

if i had left the screen intact on my 99z....i wouldn't have had a small hose clamp get sucked up into the engine and scar the heads and bend a valve.

i say leave it in
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Old 06-28-2005, 09:05 AM
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Re: descreen or not to descreen..

I would leave it in. If some day you put a huge cam and heads on your car,it makes it harder to tune at idle. The reason being that the screen straightens the air going over the sensor. Thus keeping a nice flow over it at idle. If its not there the air will pulsate back and forth over the sensor and make it harder to tune at idle. I ve tuned cars both ways and have not seen any horsepower gain by taking it out.
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Old 06-28-2005, 07:51 PM
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Re: descreen or not to descreen..

I had the screen out and have long since put it back in. I even put the stock MAF ends back on. I had the ported ones and never noticed any difference with or without. But as said in 1 of the past posts even a bug down there isnt a good thing.
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Old 06-28-2005, 09:10 PM
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Re: descreen or not to descreen..

leave the MAF untouched. If you ever look in the "parts wanted" section, you will often see people looking for untouched stock MAFs... there is a reason for that.
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Old 06-28-2005, 11:23 PM
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Re: descreen or not to descreen..

I took mine out in '89 an I've never had any problems,as for sucking things into the engine, isn't that what the air filter is for. It doesn't make a noticable differance,but I believe every little bit helps to a point. If you do it keep a good air filter in line and you should be ok.
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Old 06-29-2005, 12:33 AM
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Re: descreen or not to descreen..

Take your screen out and send it to me!

Really though, just leave it alone....
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Old 06-29-2005, 12:38 AM
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Re: descreen or not to descreen..

Originally Posted by teke184
on a side not...

if i had left the screen intact on my 99z....i wouldn't have had a small hose clamp get sucked up into the engine and scar the heads and bend a valve.

i say leave it in
how TF did a hose clamp get past the air filter?
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Old 06-29-2005, 06:13 AM
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Re: descreen or not to descreen..

all i can figure is while i had the lid/intake off one time when working on something, most likely doing the TBB, i set the clamp on top of the filter (makes a handy tool tray...NOT) and then forgot to pick it up.

put the lid back on and fired the car.....SUCK...right into the engine.
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Old 06-29-2005, 08:39 AM
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Re: descreen or not to descreen..

Originally Posted by IROC-T
I took mine out in '89 an I've never had any problems,as for sucking things into the engine, isn't that what the air filter is for. It doesn't make a noticable differance,but I believe every little bit helps to a point. If you do it keep a good air filter in line and you should be ok.
The 3rd GEN Bosch MAF sensors are dogs.... they have two metallic screens and all the internal cooling fins, and removing the screens and the fins can eliminate a bottleneck as HP increases. However the 4th Gen LT1 and LS1 cars use a GM MAF sensor, with a single formed paper/foil honeycomb in the MAF inlet side. That device is provided to smooth the airflow through the MAF sensor, making it more uniform across the full open face of the sensor. That way, the small amount of air that actually touches the sensing element is more representative of the true flow through the entire MAF. The factory assumed the screen was there when they set up the MAF calibration curve in the PCM. If you remove the screen, you alter the calibration.

Removing the screen isn't going to increase flow by 180cfm. It will eliminate a tiny pressure loss, increasing what's left of the barometric pressure by the time it gets done filling the cylinder volume. That's effectively a tiny increase in volumetric efficiency. IF you assume that removing the screen reduces the pressure loss through the MAF (it might actually increase the pressure drop if it screws up flow ) by about 0.1"Hg the resulting flow increase is 0.33%.... or on an engine consuming 400cfm, you would gain approx. 1.34cfm. Not worth it, if it screws up the meter calibration.

Last edited by Injuneer; 06-29-2005 at 08:41 AM.
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Old 06-29-2005, 09:11 AM
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Re: descreen or not to descreen..

he who many of us lovingly refer to as The Man....has spoken

if you need any more explaination than that...
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Old 06-29-2005, 04:24 PM
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Re: descreen or not to descreen..

Originally Posted by Injuneer
The 3rd GEN Bosch MAF sensors are dogs.... they have two metallic screens and all the internal cooling fins, and removing the screens and the fins can eliminate a bottleneck as HP increases. However the 4th Gen LT1 and LS1 cars use a GM MAF sensor, with a single formed paper/foil honeycomb in the MAF inlet side. That device is provided to smooth the airflow through the MAF sensor, making it more uniform across the full open face of the sensor. That way, the small amount of air that actually touches the sensing element is more representative of the true flow through the entire MAF. The factory assumed the screen was there when they set up the MAF calibration curve in the PCM. If you remove the screen, you alter the calibration.

Removing the screen isn't going to increase flow by 180cfm. It will eliminate a tiny pressure loss, increasing what's left of the barometric pressure by the time it gets done filling the cylinder volume. That's effectively a tiny increase in volumetric efficiency. IF you assume that removing the screen reduces the pressure loss through the MAF (it might actually increase the pressure drop if it screws up flow ) by about 0.1"Hg the resulting flow increase is 0.33%.... or on an engine consuming 400cfm, you would gain approx. 1.34cfm. Not worth it, if it screws up the meter calibration.

This is good to know info that I was unaware of will file it for future referance. How ever he didn't mention if it was a third or fourth gen. Is one to assume that General F-body Tech means fourth gen?
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Old 06-29-2005, 05:23 PM
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Re: descreen or not to descreen..

Originally Posted by IROC-T
This is good to know info that I was unaware of will file it for future referance. How ever he didn't mention if it was a third or fourth gen. Is one to assume that General F-body Tech means fourth gen?
You make a good point there.... I'm perpetually telling people to add a "signature" with basic info like the year of their car, to help us answer their questions. I honestly don't know what he has... I was just pointing out that the answer is different, depending on whether he has a 3rd Gen or 4th Gen. One size does not fit all.....
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