i know there are screens on the maf's on the lt1 and ls1 engines that you can remove and get free power and i would like to know how similar the maf sensors on our cars are and if i can take these screens off of our sensors. thanks

 

Yes there are screens that can easily be removed that has been stated will increase airflow. I removed mine about a year ago and no problems. But remember GM put them there for a reason(keep stuff from going inside the MAF and killing the TINY hotwire). I didn't notice any difference and this part cost like $300.00+ so think hard before you do it!

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See my Ride:
https://www.thirdgen.org/rides/index...ew&rideid=1324

 

Do a search her on the forum and you will find alot of information about gutting your MAF. Read Vaders topic and you will come to the conclusion- Not to do it...

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GTA -89:383, 4-bolt,Free flow muffler,dual 3" HF cats, Edelbrock headers, Canfield heads, 1.52 RR 7/16, ZZ-9 cam, Big Mouth, AS&M LTR, !plenum, 52 TB, MSD 6AL, TPIS level V prom, Superior shift-kit and all the minor mods,looking for a SR ...
http://www.itv.se/tacs/members_cars/m279/m279.html (Swedish Trans Am Club)

 

I question the reasoning behind the screens being there (to block particles from destoying the wire). If something is small enough to manage to get past the air filter, those screens aren't going to do crap. I've also heard the are there to straighten the air flow. Does any know for sure what the reason behind them are?

 

Yes, the screens are there to straighten the airflow also while keeping stuff away from the wire.

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89 RS

STILL Looking For:
An 87 IROC-Z28 350 TPI

 

Here we go again! This is another FAQ.

The MAF screens do not straighten airflow. I will try to define as clearly and concisely the intended purpose of the screens (which I do not for a second buy into, its only theoretical). You may have to read it a few times though.

The purpose of the screens is to create more turbulence in the air. The idea behind adding turbulence is to attempt to create air velocities across the entire cross section of the MAF that are as close to equal with each other and as close to the average velocity across the entire cross section of the MAF as possible. This is supposed to create a more accurate reading of the airflow going into the engine.

Get it?
Maybe I should draw pictures.

Regardless of what you might interpret the purpose as, they slow down the airflow into the engine, as they are a restriction in the tract. The significance of the restriction is whats important here... is it important enough for you to remove the screens or not? Mine just so happen to be gone. If you go the route of removing them, treat the MAF like its the most fragile thing you have ever put your hands on and you will be fine... just dont treat it like its a superball or something.

[This message has been edited by madmax (edited August 27, 2001).]

 

I believe the term used to describe what the screens do is "cavitation". (EXACTLY what madMax described above)

John

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87 Formula Yellow/Black

5.1 TPI Automatic
Baer 12" brakes 4 wheels, KYB AGX Adjustable Shocks & struts, Custom Leather interior, WAAAY TOO MANY MODS TO LIST

87 Formula TPI (5 Speed) Yellow/Gray STOCK

1967 Buick Riviera 430hp Turns high 14's (Not bad for 4300 lbs)

83 Camaro (Parts)
83 T/A (parts)

http://www.3rdgenformula.com

 

Thanks for the info. Sorry, didn't check the FAQ. I just knew it didn't make sense for it to stop particles.

 

Its all good...

It can stop particles... large ones... like if theres a hole in your air filter or your air filter is missing entirely.

 

If you are reaching the flow limits of a stock MAF, you might want to consider a different MAF or converting to a speed-density scheme and custom PROM.

If you are running a 305 at 6,500+ RPM, or a 350 at 5,500 RPM consistently, the MAF will start to be a restriction. If you are running at those RPMs and producing ANY torque at all, you're already not using a stock TPI, so it won't be an issue. Below those engine speeds on their respective engines, the MAF restiction is not significant.

Just my 2¢

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Later,
Vader
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"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

 

That brings up a question I've been thinking about. Will a 4th gen or any other MAF work in our cars? Just wondering.

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See my Ride:
https://www.thirdgen.org/rides/index...ew&rideid=1324

 

LOL, I get why they don't straighten air, and don't really keep stuff from the wire because the air filters are good enough, (don't know what I was thinking!!) but I don't exactly get how they make airflow measurements more accurate yet.

If you'd like to, go ahead.

[This message has been edited by IROCZTWENTYGR8 (edited August 29, 2001).]

 

Airflow across the cross-section of a tube(a MAF in this case) is not uniform. The air at the center is considerably denser and moves faster than the air near, or at, the walls. because the MAF only measures air at the center of the main tube(the sensing wire is inside a smaller tube), you actually get a distorted sense of air quality throughout the tube. By putting a restriction(the screens) at the inlet and outlet of the tube you create tumble inside the tube, which slows the air down and lowers it's density, so that you can get a better average reading. Of course the downside to using a restriction is that,.... it's a restriction(Gawd I have a gift for stating the obvious )

 

Removing the screens in my car (87GN with LS1 MAF). Actually slowed the car down.

Removing the foil inside was an aid thou.

I hate to spoil so many opinions, but the facts are:
The screens are there to min turbulence as the air flows over the sensing element. removing the screens allows for more turbulence and skews the calibration. In some cars it can help, some hurt, but in anycase is just a poor way to do things, the corect answer is having a prom with the right calibration in it.

In the new vettes they removed the screens, BUT ALSO, they straightened out the air tract pre MAF sensor to do so.

Depending on what brand calibration MAF you run there might be a cone shaped piece in the center of the unit, that is to minimise false air flow reporting due to reversion.

 

Here we go again, another expert.

Ill deal with the explanation later or refer you to another post (by me as well) but adding screens adds about 1000 vortices behind the screen wires, which causes a low pressure spot, which is a turbulent condition. Period.

 

Vortex?

vor·tex (vôrtks)
n. pl. vor·tex·es or vor·ti·ces (-t-sz)
A spiral motion of fluid within a limited area, especially a whirling mass of water or air that sucks everything near it toward its center.

Votex, by example are due to the spanwise flow of air off of a tip of a wing.

The screens cause no spiral motion.

 

O.K. Before this gets away from us, let's cover the facts. Besides, it's a lot more fun to save the punishment for the Mousetank and ***** drivers.

The stock Bosch MAF has screens in both ends for a couple of reasons. Accurate air mass measurement is one of them, regardless of whether you call it induced turbulence, vorticies, delamination, etc. We know what you mean. the air needs to flow through the body relatively evenly so the sampling tube gets the most accurate sample.

Sonic shockwave protection of the hot wire is another function of the screens, whether from lean backfire or intake valve pulses (you know, the waves that make the TPI theory work in the first place!).

Suffice it to say that some people have removed them with some success, and some people have removed them with some detrimental results.

If you do the homework, you might discover that the stock unit flows enough for most applications (especially 305s), and doesn't need any modifications to improve overall performance. Some engines can benefit from the increased flow, as long as the sample rate is correct (or at least close).

I'll also agree with Grumpy that altering a digital MAF on an LT1 (and probably the Buicks) is usually a bad idea. For the reason he stated, altering the MAF (or even altering fuel pressure more than a few PSI on an LT1) will actually cost you some power unless you do some control modifications. The dyno sheets posted at the SS sites show a loss of power with fuel pressure above 44PSI and with an altered MAF.

Programming seems to be the correct way to tune for power on these engines, whereas the older control of the MAF ThirdGens is a bit more forgiving and less sophisticated, allowing some more adjsutment on stock programming.

In a nutshell, alter at your own risk - but don't be surprised if you get no gain (or even a loss) of performance.

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Later,
Vader
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"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

 

??.
Why on the latest versions did they delete them if the above is true?.
It would be intersting to see if there is any sonic flow that far out from an intake valve, but with all the bends and twists, I would find it hard to imagine that a sonic wave could exist.

 

Yes they do. Go to a bridge sometime that has round columns for supports. The water acts the same as the air does. They actually design bridge supports now that mimic airplane wings, they are round on the leading edge and tapered on the trailing edge to prevent erosion of the concrete from the turbulent water on the trailing side of the support. I have seen this in the lab too many times to count, not only with water in a flume but with air in a supersonic wind tunnel.

Someone was nice enough to give me a good idea mentioning an aerator for a sink. Its just a screen (like the MAF screen) in the path of the water. The purpose is, to add air to the water. The air is brought in through the water from the edges towards the center because the water is broken up as it passes through the screen enough that the low pressure areas if you could even say water does that are filled with the air immediately surrounding the column of water from the faucet. It is a turbulent condition that causes this. Since air is compressible, and there is no extra air filling the voids caused by the screens, the air pressure changes behind each wire of the screen. Its possible, like most others, you are using the wrong term to describe what is going on, it would be more like a steady state condition after it passes through the screens than before.

I myself have heard of more than a few people who went slower with their LS1's after messing with the MAF. There are too many conditions to pick out why some are working and the rest are not. If I use my TA when it was stock as an example, its probably the worst setup to remove the screens from because there is a 45 degree bend in a round tube with a sharp edge on the narrow side. I'm 99% sure most of the air is coming past that bend all forced over to the side opposite the cooling fins and above the sensing element of the MAF. This probably does wonders for airflow into the engine because its in the least restrictive part of the MAF sensor as it passes through. If this was the case (which I never attempted to verify) the reading would be in error since most of the air is not passing the heated wire. Such is life.

Im a stickler for terminology, and the screens definitely do not reduce turbulence. They may create an airflow that could be measured at any point in the MAF sensor that would be the same (what I said in my post above) but its certainly not less turbulent.

 

Hmmmmmm........ never thought about that. Yet another reason to get a forced induction setup..... lol........

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23* Heads, LT4 Hot Cam, Ported plenum and intake base, SLP Siam Runners, BBK 52mm TB, Edelbrock TES, gutted Cat, Flowmaster, CAI w/K+N cone, AFPR, TB bypass, !AIR, !A/C, !EVAP, ARAP, 2400 stall, Alum. Driveshaft, Fourth Gen 3.42 Rear, Spohn LCAs and Panhard, Hotchkis STB, '99 Camaro seats.

G-tech time:
(w/ lotsa wheelspin)
13.45@109.3mph

 

i have an idea...however,dont rip me apart if its stupid..its 8:23am,and ive been awake for 88 of the past 96 hours and i cant think,but i beleive this will give an idea...
if you smoke...go light up a cigarette...
if you have old style mesh screens in your windows of your house,you can do this,otherwise,just enjoy the smoke,lol...
open the window,with the screen closed....
inhale the cigarette,and blow into the screen,however the smoke comes out the other side of the screen,is basically how the air will be going through your MAF screens....am i off base on this???
then just inhale,and blow into open air,and thats what the air will do in a screenless MAF......

main thing i wanna say it,like stated earlier in this thread,if you decide to de-screen your MAF treat it very carefully,cuz that tiny *** little wire doesnt take much to break...
what i did was i took two bottle caps from 1 liter pepsi bottles(wide mouth) cut slot in the ridge about 1/4" widex 1/4" deep on each one and slide them over the cylinder thing with the wire inside....that way,if anything would have fallen into the wire tube thingy,you dont have to worry....i didnt notice any drawbacks on performance or anything by gutting mine,and i wasnt worried about my wire snapping,cuz i have a spare MAF
either way,i just figured id add my $0.02


Andy

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The "House" has spoken...
check out my my 88 WS6 Trans Am

We are the seeds of legends,our true origins are unknown...WE SIMPLY ARE...

 

Well, not quite.

My GN runs better with the screen in the MAF then with it removed. Thou it does run better with the divider removed (Late style MAF)

 

Grumpy,

All the "latest version" MAFs I have don't use the fragile hot wire, but incorporate a thick-film sensing element to dissipate heat energy to the surrounding air instead. This design has been in use since 1993, and this is the same design as the retorfit Wells MAF sensor, and the reason there is no screen on the exit end of the sensor.

------------------
Later,
Vader
------------------
"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

 

GM took the screens out of the MAF for the '02 'Vette to squeeze out some horsepower. No doubt to realize gains, not make them. Nevertheless, they did it. Check out this month's CHP and Hot Rod.

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-Greg

'85 Trans Am - WS6,TPI:
Original owner, original paint/engine/interior, plus the usual bolt-ons

[This message has been edited by Greg '85 T/A (edited September 04, 2001).]