z28monster

iTrader: (1)

hey guys as you can see i own an 86 iroc-z with a 305 tpi engine i was taking the air filters out the other day and puting in new ones and i noticed that the MAF senser thing with a screen in it and i noticed that the screen was torn pretty bad.... is it me or did i hear from some ware that if you take the whole screen out that it will give you a performance increase or is that wrong. or should i just buy a new unripped one.

also when i start my car up when it is cold it stumbles for a couple seconds then the rpms kick up eventualy and it runs right does this ripped screen have anything to do with that?

1989GTATransAm

iTrader: (3)

The air flow over the sensor in the MAF is very important. I would either replace the screen or get rid of it. You do not want air turbulance around sensor. I have known people to use certain types of flex hose in front of the MAF and it did not work out so well. Allen

z28monster

iTrader: (1)

can i actualy rip that little screen out of the maf sencer or does the maf need that to work right??? im new to tpi lol im used to carbed engines so this is all new to me.

1989GTATransAm

iTrader: (3)

I removed both screens from mine. If you should decide to replace it see how the existing screen is orientated and install the new one the same way. Allen

rezinn

In camaros, where air comes straight in and passed right to the sensor, the front screen is not critical. It would probably be better to remove it than have a torn one.

BADASS91B4C

if u remove the screens u get a hp boost

z28monster

iTrader: (1)

so if i gut the screens out it will give me a power increase??? with out throwing me codes? if this is true i plan on gutting the air box and the screens and installing K&N air filters in the air box... but i need to know for sure that removing the screens is a good idea

razor

How many gms/sec is your engine pulling right now??? With a 305 tpi you will not even be close to ever getting 255gms/sec.You could have heads/cam/exhaust and some induction work and still not max it out. I can speak from personal experience on this one. My car has the screens removed and I am thinking about buying a new maf with screens intact. Why???? Because it ruins the calibration. And not in a linear sense. I have certian cells in my datalogs that run rich because of this. My vote is don't take the screen out unless it poses a threat of coming unattached.

BLACK ICE

It is cheaper to take the screens out and risk taking an ever so slight gain or loss than it is to buy a new one. I took my screens out and did not feel a difference but then I gutted my air box and I felt a huge difference! the only downside of gutting is you risk geting wet filters in the rain (and wet filters suck). Your choice.

P.S. T.P.I.S. has literature on boosting performance in tpi motors and that is one of the things they recomend (removing screens) and to fully mod your maf sensor shave out the heat sinks inside. if you have a filter no harm should be done!

z28monster

iTrader: (1)

so instead of buying a new one i can just rip the torn screen out and gut my air box and notice a nice power increase with out any computer problems? doesnt the MAF tell the cpu how much air the engine is taking in and buy removing the screen youd think it wouldnt be able to do this corectly so wouldnt it make the engien run bad.

BLACK ICE

I would take out both screens but yes you will increase your airflow. T.P.I.S. claims that a stock maf will flow about 434 cfm and one with the screens taken out will flow about 512 or about a 78cfm gain. So technically yes It will help your performance however like I said I did not notice untill I modified my box. You should not have to worry about you computer because you are not running a speed density system. You are running mass air witch does not run on preset values as speed density does. Mass air has learning capabilitys and can compinsate for changes up to almost 400hp.

Guest

I love these posts

The orientation of the screen makes absolutely no difference at all.

As for taking it out or not, mine have been gone longer than I have owned the car, and thats been a long time.

DJP87Z28

Also to be on the safe side after you destory the Maf Sensor, have a extra couple Hundred Dollars around to buy a new one.

z28monster

iTrader: (1)

well i just got done taking the screens out... and when i first started it , it didnt run as smooth as it usualy does so i turned it off then when i started it back up it ran fine... im guess the computer was adjusting to the difference and compensating for no screens in the maf the rest of the MAF is all intact so i think ill be fine.

also i havent gutted the botoms out of my air box yet because im scared to because i herd it will suck in water in the rain... should i go ahead and do it or is this a real big problem in the rain... i dont plan on driving this car in the rain but if i am cought in the rain id like to be able to get home... should i do it and also how much of a power increase should i expect? will it be noticable?

BLACK ICE

I gutted my airbox and it made a huge difference the car pulls alot harder. Dont really feel like looking up the cfms right now but I know it is considerable. the next step for mine now is ram air. Ill tell you how it goes when I get around to doing it.

ChevyGuy5

is there any disadvantage or harm that could be done if i remove the screen?

z28monster

iTrader: (1)

i think the only thing that could happen is if you dont have an air filter there is a chance that you could suck something in and take out the thin little wires that make your MAF work.... the screans are just a protector for the MAF sensor.

Jekyll & Hyde

The screens are there for two reasons. As I read the replies here, it is noticable that most people will not agree, but do a search and you will find out.

The screens are there for protection of the wire and and to straighten flow. It will give a hp increase from the screens not being there, if you actually max out the gms/sec. Which a 305 won't. Removing them will make it a little tougher for the computer, and in the end harder for you as a tuner.

If you do not plan on burning your own proms, remove the screens.

If you do a search in the diy prom, you will read some conclusions of why the screens are there.

Guest

Tell me how a screen straightens flow.

z28monster

iTrader: (1)

yes id also like to know how it straitens the air flow.... also why was it said it is a good thing to do if you dont plan on burning your own proms? im new to feul injection so bare with me...

also is this a MAF sensor and if yes is this the type of sensor that can handle me putting in a larger cam and make all the adjustments its self? or do i have to switch to a diff one to be able to put a larger cam in this engine?

Jekyll & Hyde

You can't be serious, right? What do you think is going to happen when it gets to the screens?

~> #
~> #

The screens were put in place to slow the velocity down enough to keep the pulses from messing with the meter (maf sensor). How are you going to be able to measure something correctly when it is turbulant?

If you have a scanner for your car, you can even watch that the gms/sec will jump around (scavenge) more with the screens gone. <-- Making it harder to tune for the n00bs

Not really a big deal if you are going to running jet and hypertech chips. Pain if you are n00b trying to tune it yourself though.

Z28 Monster -->

MAF TPI cars will take a larger cam easier. The stock one is large enough for almost everyone here. Unless you are putting down 550+ to the rear wheels you shouldn't need to worry. Ski_Down_It has proved this by measuring vaccum while on the dyno and putting down about 480rwhp...can't remember exactlly. He never had any vaccum from the intake tract, meaning the maf was not maxed out. He even video taped it all for the non-believers out there.

Jekyll & Hyde

For the flamers that are getting ready to pounce.

Did a google search for you guys, here is one that it returned me to:



http://www.gmtips.com/3rd-degree/dox...maf-screen.htm

z28monster

iTrader: (1)

Not really a big deal if you are going to running jet and hypertech chips. Pain if you are n00b trying to tune it yourself though.



i have a hyper tech chip in my car so will i be fine.... also can soem one give me some info on the hyper tech chips and exactly what they do... it was in my car when i bought it.

also being my car is MAF can i go ahead and make a cam upgrade and not have to worry about burning a custom chip for the computer? in 85 the iroc tpi engine put out 215 hp but in 86 it droped to 190 hp due to a cam change id liek to get a bit better cam then the 85 version and try to get a bit more then 215 out of it can this be done?

Guest

I see you have no scientific backup to your claim that it straightens air out. Thats what I figured... probably because it doesnt exist, but anyway I digress.

Here's a better place to look, that link you posted was written by the same guy in this post, MikeinAZ

https://www.thirdgen.org/techbb2/sho...threadid=45637

All you wanted to know, and more. And thats just the tip of the iceberg. Take note of some of the real life comparisons at the bottom. You might find it interesting, and learn something about what happens in real life as compared to theory.

Jekyll & Hyde

You must be retarded and can't read or something.

This was posted in the "real-life" section that you wanted me to read.


I never said that the screens were better or worse for the system.
Here is what I said:
As for the screen door or window that he heard the whistling from, it is nearly impossible for him to prove that there was a swirling effect. There has to be enough vaccum to create a void, a screen wouldn't have enough.

I guess you are going to focus on one word though, and the only basis for whatever you are trying to prove, maybe I should have said straightens, I should have say steadies.

Guest

What, does everyone here have a 2nd grade education? In the past week, I've been called a moron and retarded. Funny thing is, you guys are all still playing catch up to where I was 5 years ago. Where does that leave you?

Anyway I read just fine, you dont. THIS is what you said and I questioned:

Who's the one who cant read again? Geesh... try to help people and all they do is call ya names. Grow up.

PS:
As for your quote of the link I posted, I suggested to read it and learn from it. You didnt learn much, I see. Go read the whole post. Pay attention to what the fence did to the flowrate. Think about how an aerator on a faucet works. There are a few significant things happening here, and since nobody seems to get it, I will try to spell it out at the 2nd grade level.

1. The screen slows down the air. You can view this as you like, but:
a) its a reduction in area
b) its a change of path of flow
c) directly at the screen there is more turbulence present than if there was no screen present. This turbulent condition doesnt just immediately disappear either
d) numerous low pressure areas are created at the back side of each screen wire

I can think of a few references or explanations to explain this. First, assume that you have 1 molecule of air, and it is traveling directly at a single wire of the screen. What does it do? It has momentum... it has a direction, towards the wire. Its kinda like pool, with a couple ***** on the table. The molecule deflects. If you want to tell me that makes it straighter, go right ahead so I can laugh a little harder.
Now picture, say, 3 molecules. One just on each side of the wire, and one directly at the wire. Lets assume we're in a single plane, so the center molecule must deflect and disturb one of the other molecules. If you are to imagine a constant density being the even spacing before the wire, and the inconsistent spacing after the wire with 2 on one side with a different path of travel and one with the original path of travel, you are left with a less dense or low pressure area beyond the wire until the void is filled. Is this all making sense now?

2. The inherent reduction in velocity causes the flow to return to more of a steady-state condition.

Dont know what to tell you here, but I'll try. If you go to your sink and turn on the water just as low as possible to get a stream, what do you see? A very steady and even flow. All the water is staying in one general location. Now open the valve all the way. What happens? If your water pressure is good enough, you might even feel the mist. Point being... in general, a slower flowrate is more likely to be a steady-state condition than a faster flowrate.

3. The resultant flow across the heated MAF wire is, in all likeliness, turbulent

Why? Well, the screens disturb the natural order of the flow, whatever that might be. I'm going to add a picture here, to describe a few basic things and the general intent of whats really going on inside the MAF.



This is my best guess at whats really going on. If someone wants to refute it, go ahead and cite your source and reason and I'll change it. I'm sure its not perfect, its just intended to be an example of what is probably happening. Most important is what the MAF thinks it sees. If you take the fantasyland true laminar flow, you have the perfect situation and there is no error. Ideal laminar flow doesnt really exist in reality either, but its generally used because to most people in my field the finer details dont matter. Maybe with the screens out, the MAF might see a high or low reading, dependant upon where the path of the air truly is. Think jetstream, you know the kind you see on the weather. It doesnt stay in the same place, it moves. This is entirely possible in the intake system, with different flowrates and obstructions. I have actually reversed a S shaped flowpath with a particular obstruction and different flowrates in lab testing with water. Cant see why air and an intake would act any differently if the situation was right. The screens flow is what the intention is. They are trying to match the 'True' laminar flow. If you slow the air down enough, you could probably come real close. The price you pay for 'accuracy'. Thats the whole idea behind the design, consistency, repeatability. And there very well might be molecules going the wrong way, filling a low pressure spot... but the 'general' direction and AVERAGE flowrate is intended to be linear with different flowrates instead of a curve, and repeatable with different entries and exits or different locations of the high pressure flow location. The last is exactly what you dont want, your reading could be in error depending upon where you read. Bad.

Water so happens to be an excellent place to learn a little bit about fluids and how they behave. Air isnt identical because water isnt technically compressible and air is, but the basics are still there and once you have a handle on those you can learn a bit about the more complex behaviors of a compressible fluid.

Whats the point? The only intention of the screen is an attempt to regulate the airflow and try to create a more steady-state condition so that the measurement is more accurate. Its extremely difficult to make an accurate flow measurement on a fluid that isnt steady. You can take a bunch of measurements and get close, but accurate is not where you are at. More than likely due to the slight differences in the air tracts of the Firebird, Camaro, and Corvette... and the fact that Bosch wanted a 'universal' device that could be relatively accurate in any installation, they added screens.

Are they necessary? All depends on what you feel is necessary. Personally, if I had the choice of building a bridge with piers in the river or a single span with no piers, and the maximum flowrate of the water was a main concern, I wouldnt be sticking anything in its path. Becomes a concern to me when I have short banks and high flows from a major storm, my only concern is that the water doesnt top the banks and flood someone's house. Now, if my intention was to be able to accurately measure the flow of the water at all times (and this is with crude devices I might add), I'd stick an obstruction in the path and the resulting condition would allow me to deal with a much more steady flow. I dont have the liberty of an oxygen sensor telling me that my reading was wrong. Thats where the MAF in the car differs, it has a calibration table that, if you burn your own chips, is readily accessible for correction.

Retarded.
Maybe my ignition timing, but only under boost.

Jekyll & Hyde

So you don't have proof of it either. Seems like this will never be proven with out building a wind tunnel for a maf sensor.

You come in here and post some pictures that you made and say this is your best guess. I already said that typed the wrong word in, and what I was letting everyone else know is the truth. It will scavenge the computer if the screens are gone.

The screens ARE there for more than protection and they don't just TRY to regulate the flow...they do. Get a scanner out and test both with screens and without.

Guest

I already have datalogged cars before and after. Dont need to do it again to see the end result.

I dont have proof? I based those diagrams on what is published in technical books and what I have observed in the past. I havent actually run a MAF with a visible airstream, but who cares? The concepts are all the same. This is basic fluid dynamics... it doesnt change just because you have an electronic device from a car. Just putting a sphere on a rod in an airstream and observing the air traveling around the rod and the length of the disturbance will show you what a difference there is between no obstruction and that obstruction, and how the air behaves because of it. Then you throw a couple in there and all sorts of weird stuff with confluence happens. I'm not gonna sit here and draw up a 5 page essay just to educate those who havent tested, read, and learned the material, just going to try to point you in the right direction and leave it up to you to learn from it.

Jekyll & Hyde

What did the MAF sensor read before/after you removed the screens. Again that is all that I am saying.

The screen is seperated by equal measurements, this would create a steady measurement for the MAF. You can't deny it, and many times you have just proven what I have been saying. Thank you for that.