MyBlackRocZ

i was at the track to day and ran 14.4@93 and then decided it was time to take the screens out of the maf. Next run......14.0@96
i picked up 4 tenths and 3 mph just from the descreening the maf

so anyone that hasnt done this mod just

DO IT!!!

i couldnt get over it

IROCKER

I did it and two months later and $250 less I had a new rescreen MAF back in the car. I don't know what happen because the car worked fine for weeks and then toasted MAF. It's way too expensive to attempt again.

IROCKER

Apparently Wells sells a aftermarket MAF for our cars that uses a different system than the hot wire system of the Bosch MAF and flows better as well (750CFM). I can't remember the Wells part number...does anyone else know it?

u r sofa king we tah did

30hp from descreening the MAF, not bad. now removing the spare should net you a half a second or so.

smokin87iroc

I have to agree the 3 mph from descreening the MAF is you really won't feel a difference. what were your 60ft times? what were your ETs?
you can do totally different things on 2 runs so you can't say something from only one run.
Andrew

Iroc n roll

De-screening the MAF is a risky thing. Probably not worth it. I guess I'm not one to talk since I've done it though. My MAF is still good and I've had no problems, but then again I haven't really had gains either. I had heard the horror stories like Irocker's and so have many others. I believe that the general consesus is that maybe taking the screens off will give you a bit more flow, but even if it does, it's not enough to justify the chance of a wrecked MAF.

Z28DJP1987

IROCKER
The p/n for the Well's MAF is SU145.

anesthes

iTrader: (12)

Removing the screens is important. I found a 3-4 tenth gain as well, among other things, the air cleaner, where it sucks in air, etc..

Eventually, I ended up replacing runners, boring out my TB to 52MM, airfoil, and finally a vortech supercharger. Hoping for high 11s this April.

But I'm an advocate for ripping the screens out.. Even if you do break it, its like $100.00 for a new one at Autozone, which is pennies compared to other things..

-- Joe

Iroc n roll

I gotta throw the flag on this one guys, those gains are just too much. I'm not doubting your track times, or even that the de-screening the MAF gives some kind of improvement. But it certainly does not give 3-4 tenths alone. The must be other variables at play. Traction, human error, temperature, winds and the car's running condition all play a factor in track times. Variations in these can cause a 3-4 tenth difference between two track runs. Smokin87iroc pointed this out earlier. If you ran a consisnet average of 14.4 for 3 or 5 runs and then the same day in the same conditions de-screened your MAF and ran a consistent average of 14.0 for 3 or 5 runs, that would be some significant evidence

tpi_roc

Screw cams and heads, I'm pulling out my fuel filter for .5 and 6mph!!!

poncho9789

LOL@tpi_roc Will that really result in a gain!

I very seriously doubt those kind of gains too. I would probably just put the explanition to driving ability. I have heard people say the stock will flow fine for a 350 up to like 5k. Removing the screen will definatly result in a gain but more like 3-4 hp not tenths in the 1/4. You would have to gain like 30hp to get a gain in the 1/4 like that.

85transamtpi

If you had dyno pulls then you would have PROOF. What you have is one run that is better than others. I would guess it is because you let your car cool off (as you removed the screens). Personaly I wouldnt touch this mod with a 10 foot pole. I know too many people who found themselves $300 poorer, and just as slow in the long run.

-peace

monte-ss

you guys must have not done something correctly when descreening the MAF my buddy was attempting to help me take mine ou when he slippedand tossed the MAF across the room bouncing off of everything (thank *** we worked in a parts store) but I stuck it on after completely descreening and attempting to cut out some of the fins (didnt have a file or patience to finish off) and put it back, that was almost 2 years ago, and Ive had the MAF off and on several times doing other work, and it still worksgreat, even ran it thrugh the mohave desert while on vacation last summer, not one problem ever yet knock on wood!!

anesthes

iTrader: (12)

On a flow bench with the screens removed you gain something like 144cfm.

We cool the cars down to 150 after every run..

-- Joe

Z28DJP1987

The Wells MAF flows 750cfm stock and only has one screen. I have picked up 4 rwhp on my last dyno run.

88gta305

The stock MAF flows a well documented 434 cfm.
Just in case anyone really wants to know.

Cheers

Richard

poncho9789

I think the one Vader reccomends flows 750 it is a different style maf made by wells. It has the element style of a fourth gen.

AaronIROCZ

iTrader: (5)

To all you guys descreening your maf for more cfm you also have to take this into account. You can put the biggest maf on your car that you can find but the problem is that the computer has a limit of only reading 255 grams per second of air. A stock engine will probably never get that far but if you starting to modify your engine this becomes more of an issue. The ONLY way around this is to convert to speed density. There is no way around this. Just my .02 worth.

MyBlackRocZ

the 14.09 run was imediatly backed up by a 14.10 . both on 1.9 short times.

'87FAKE-IROC-Z

I think that Wells MAF is a heated film type and the stockers are heated wire type.
I have had my screens out for over 2 years now with no problems, but no power was found either! I am also maxing this damn thing out with the new engine.

Ted J

That doesn't prove anything to me. Tell me how many people you know that run at the track and stay within even .1 or .2 of their times that aren't professional racers or have their cars professionally set up? How long did you let the car sit inbetween runs? If it took you a while to descreen the MAF maybe the motor cooled off and that got you some more ponies? Just some points for you to keep in mind.

I've ran up to .3 to .5 difference in time in one night and that was just cause of a difference in launching. My MPH is usually pretty close but when I first started out my MPH got better and better each run.

I've heard that people with LT1's and some LS1's also have problems with the motor running to lean when you descreen the MAF. It makes sense, I mean, there is more air going into the motor than the computer knows about so I can see it causing this.

I choose not to descreen my MAF on my LT1 powered car for the chance that it could add power is less than that of the chance it could cause issues. I'm for more power in any way I can get it but not at the expense of it causing other issues or costing me money to get a new MAF or fix other things.

Just my $.02 though.

anesthes

iTrader: (12)

Hey Guys,

255 grams per second = about 540CFM limitation..

You can't up that in the prom?

That sounds a bit too low, especially for us who have superchagers that push around 1,000 CFM..

Then again, thats probably what the FMU is for.. -

-- Joe

a73camaro

Tough crowd here. You even have two back to back runs and people are calling you a liar.

The 3 MPH increase indicates that you increased HP. Similar 60 ft times with quicker et also indicate more HP.


Now my question, was the air box and filter also connected in each case?

BTW, with an auto, good tune, and good traction, you can repeat runs within 0.15 seconds easy!

88TPI406GTA

To all of you who are paranoid about killing your MAF when you remove the screens...why?

The screens are there to keep out larger debris, but they are an obvious restriction. If your air filter setup is solid, what are you worried about? Too much air somehow killing the MAF?

The stock Bosch MAF setup flows too little air. I am going to descreen it and ditch the fins as well. Or maybe just switch to a Wells MAF.

Hopefully no one who has responsed to keep the MAF stock doesn't have a bigger TB bolted on, cause that just makes zero sense.

Keep in mind that it is still a restriction in the system and you won't see drastic improvement by modding it until you have the rest of the system enhanced enough to take advantage of it.

fly89gta

iTrader: (1)

i'd like to see dyno runs. Track times do mean something but too many variables. I descreened my maf and it did nothing. I can't see gaining 3 tenths and 3 mph from removing the screens. What was the outside tempature and humidity of these runs comparing to your 14.4 run. Same track?

Z28DJP1987

I quoted in a earlier post that I gained (4) RWHP on a Dyno using the Well's MAF.

fly89gta

iTrader: (1)

not with a Well's unit, i was talking about the stocker

85transamtpi

and even if he had gained 4 rwhp...that would net him probably .001 second in the quarter mile, NOT .4 seconds and 4 mph!!

And that unit flows better than ANY stock MAF, screens or no screens.

But hey, if you want to destroy an essential sensor that is worth as much as $300, go for it! you have my blessing.

-peace

fly89gta

iTrader: (1)

couldn't have said it better myself

Iroc n roll

To the question about upping the 255g/s limit in the PROM. The limit has nothing to do with the PROM or the MAF. 3rdgens have 8-bit computers. The highest number able to be stored in an 8-bit computer is 255. The computer stores numbers in binary or base two. We count in base ten. So when we count the digits go by ones, tens, hundereds and so on. In base two digits are different. It goes by ones, twos, fours, eights, sixteens and so on. Also only ones and zeros are stored. Example:

1 = 1
2 = 01
3 = 11
4 = 101

(I know binary reads right to left but for our purposes this is easier to understand.)

So imagine 8 slots to store ones and zeros....the highest number you can store is 11111111 ....which is 255.

Matt87GTA

FYI, you can somewhat make up for the lack of the MAF being able to read above 255 g/sec in the PROM. There is a table that will allow you to control the fuel past the maxing out point of the MAF. The "PE% change to fuel/air ratio vs. RPM" table will allow you to 'control' the fuel up to 6400 rpm. If you want to spin it any higher you, need SD or DFI.

EDIT: Just as a testimony, I looked up my MAF readings and I see 230 g/sec at 5500 rpm. I rarely took it that high with the LTR setup as it just doesn't make any power up there..... But I am going to be putting an LT1 manifold on it soon, so I will soon be forced into making use of the upper regions of that table.

Iroc n roll

Correct. As Matt87GTA pointed out, even though there is a limit you can do nothing about that doesn't mean you can't still drive with it maxed out. When the MAF reaches 255g/s your car doesn't stop or anything, it just loses reliable input from the MAF. It has to start using the tables in the PROM which as as Matt said can be altered to support this problem. Some guys with the miniram have talked about this for some time and maxing out their MAF really didn't pose the problems that were expected.

L98IROCZ89

How about driver error on the first run?

Ted J

Tough crowd? Come on here and say that he's got proof that something works but only minor evidence to back it up and you don't expect him to get some feedback?

In my '96 T/A, totally stock down to the paper filter, I ran a best of 14.41 @ 97 MPH. After doing the mods I have in my sig. (and also running racing fule) I uppped that time to a 14.12 @ 99.56 MPH. I gained about two MPH out of doing a cutout and cold air kit. I'd say I was pretty consistent for one night I pulled 99.34 on every one of my runs although my times were off by a little bit depending on my launch. Still, I did a lot of things to gain that 2 MPH.

Plus. on a friends '97 SS he descreened his MAF and gained like 5 RWHP on the dyno. His motor is putting out like 450 HP though so it was needing to flow a lot of air into that motor when it was revving out to 6K or so.

It's just that with driver error and other conditions coming into play, there's no way to say that the MAF was the only thing that made the difference in the faster time is what I'm trying to say.


No argue there, but those are details that the person left out. I assume it's an auto, but don't recall seeing anywhere that it is. Good tune, who knows, maybe the first run cleaned the motor out and the second run it was running better or something like that. Traction, haven't seen any 60's times yet and there was no comments about traction coming into play yet.

Not trying to flame the guy, just trying to get some answers out of him. If he could give all the details then maybe more people might believe him.

BTW, how much air does the MAF screen really restrict anyways? I mean, after 4,500 RPM on the L98's doesn't the manifold come into play as being the weakest link? I assuem that's why LPE and Arizona Speed and Marine have upgraded runners and such right?

Grumpy

Does this mean you're willing to pay for all damages from doing this mod?. <g>

While it might help in you application, by ne means mean it is a univerally good thing. Have you checked your AFR in other conditions?.

If you want to min the intake restrictions, then go to a MAP system and get rid if the darned thing properly.

You can get rid of the screens, and use several vanes to straightne the air without the restriction of the screens. Which is the way I run my car.

The 255 limit can be tons of air per second it's just the 255 that is the limit not what it represents (when the code is modified properly). ie my MAF system reads to 510 grams/second using a LT1 MAF and a Bailey Translator.

anesthes

iTrader: (12)

I'm not sure if I understand your 8 bit limit of 255 fully.. 8 bits
of all ones is 255 - this is true, but an 8 bit processor can address in theory up to 65,535 bytes, which can roughly
store values of 255 per byte of address length.

Now if the address space assigned for this variable is 1 Byte long, then thaty limit would be true (assuming the reading realisticly started at -127, and incremented to the possible storage length of 128. But that would be silly code, rather than a physical limitation.

It sounds more like GM addressed a byte to that variable, and reads/write directly to that. But who knows..

-- Joe

poncho9789

The reason so many guys (including me)are giving you a hard time and do not believe that the gain was directly related to you de-screening the maf is that it has been tried many times. You are not the first one to try this and or bring it up on this page. Believe me if you do a search for "de-screening the maf" you would be forever reading posts about this very thing. And if done properly you might have a maf that will last years but it might not. I have a tpis descreened and de-fined maf but it was like that when I got the car. My best friend bought the maf and it didn't make a bit of difference in his time and the car was a very concistant car running 12.98 to 13.01. Point being is that everyone that has tried this mod knows it just doesn't work that well. If it gives you anything it won't be a increace of the power you would have had to develop to drop that much time.

Personally descreening a maf isn't worth the core charge the old maf is worth when your descreened maf goes out and they won't except it as a core.

Iroc n roll

I think I understand your logic, but let me try to explain alittle more. The computer is constantly receiveing and reading information from the MAF when the car is running. In the computer there was one 8-bit address dedicated to the MAF. I don't beleive its feasible to have another address for "spill-over" although it would in theory work. Of course when GM made the thing, the car was so far from maxing the limit they probably didn't think of it. The LT1 computers solved this problem by going 16-bit. One dedicated address though was probably the only way to process the info fast enough.

tpi_roc

I really gotta find more screens in my car to take out.

6 of them and I'll be in the 11's

anesthes

iTrader: (12)

I agree with you 100%, gm prolly only designed one register for that application.. Which I supose was not a "bad" idea at the time.

I sometimes wonder how tough it would be to completly replace the computer with a laptop and an interface card. I could probably write a program in a few days that monitors all sensors, and maintains them as the gm ECM does -- but I'm not enough of a hardware guy to design the board/adapter part of it..

-- Joe

IROCZTWENTYGR8

iTrader: (1)

I really don't think that what made you run .4's faster.

anesthes

iTrader: (12)

Depends on the situation. I had a breathing problem. the 144 or so CFM I picked up could make all the difference in the world.

Not everyone, perhaps hardly anyone would get the same results, but its proven on a flowbench that the screens restrict airflow, from an allready useless MAF sensor..

-- Joe

Iroc n roll

It seems like its an idea that would definitely work to bypass the ECM's restrictions. Perhaps to get around the hardware problem LT1 equipment might be able to fabbed up and reprogramed easier to use on thirdgens. Splice in LT1 sensors, take out uneccesary ones in the programing... it could work. But then again, we could go SD, which would probably be easier and a bit more cost efficient. I like the laptop idea though. If you can use that instead of the ECM you can ditch the PROM too and have easily accessible tables on the PC. IF you can find someway to get the imput to the laptop you've got a great idea there. I think that cost is the main thing. Most guys go SD or DFI. If this is acheivable for a reasonable amount, I think I might have to go out and get myself a laptop