90mm?

Definitely more than you need.

It shouldn't hurt you at that stage.

I personally would wait, and buy something else, or better yet, save your money.

Overkill for what you have......BTW i bought a used PMAS 70mm for $110 a few months back. Works like a charm.

Not too big at all. Your sig lists a 70mm meter so just save your money. But to answer your questiton, no, 90mm isn't too big.

Grn92LX said:

Not too big at all. Your sig lists a 70mm meter so just save your money. But to answer your questiton, no, 90mm isn't too big.

Click to expand...

You really have a thing for big TB's and meters don't you? Can't think of a post I have read that you said "nope, too big"

The stock TB is 55mm, or about 2-3/16". 90mm = 3-9/16". Your engine or anything for that matter can only flow as much as the smallest point of restriction, in this case, we are talking about 1-3/8" difference. A 90mm will most definitely be overkill regardless because its capability is roughly 3x the power output of a stock 5.0. If anything, the sampling element will lose it's resolution or accuracy at lower flows/RPMs and be lazier and less accurate as a meter properly sized. If you have ambition of a power added, then yeah, it will come in handy.

A 90mm would be worthless and way to big.Stick with what you got for the time being until you start altering the flow characteristics of the heads(better heads,intake,blower).Untill then i dont believe you can peg the meter with what your running.

87'GTstang said:

You really have a thing for big TB's and meters don't you? Can't think of a post I have read that you said "nope, too big"

Click to expand...

This is one of this applications where size doesn't really matter, calibration does. With that said, I wouldn't buy anything granitelli. I was just answering his post about 90mm being too big and no its not. Sure he doesn't need it but it won't slow him down

87'GTstang said:

The stock TB is 55mm, or about 2-3/16". 90mm = 3-9/16". Your engine or anything for that matter can only flow as much as the smallest point of restriction, in this case, we are talking about 1-3/8" difference. A 90mm will most definitely be overkill regardless because its capability is roughly 3x the power output of a stock 5.0. If anything, the sampling element will lose it's resolution or accuracy at lower flows/RPMs and be lazier and less accurate as a meter properly sized. If you have ambition of a power added, then yeah, it will come in handy.

Click to expand...

I have often thought about that, I wondered if the sampling size would be effected. Good points.

87'GTstang said:

If anything, the sampling element will lose it's resolution or accuracy at lower flows/RPMs and be lazier and less accurate as a meter properly sized. If you have ambition of a power added, then yeah, it will come in handy.

Click to expand...

This comment is assuming linearity of the MAF Transfer, which is not the case...
The MAF meter is most accurate in the low end.

As Grn92LX has stated...
The question is one of CALIBRATION, not size.

A quality MAF meter, regardless of the size, will perform better than a junker.
In this case the STOCK Ford meters are the best. A 90mm from a lightning will work very well, if the ecu is tuned via the J3 port.

I have no opinion on the Granatelli meters,
jason

vristang - I know you know these things.

So what if you had a 150mm MAF and a stock MAF with a calibration of 19lb injectors.

Would there be any kind of con with the huge MAF at all to to ECU?

vristang said:

As Grn92LX has stated...
The question is one of CALIBRATION, not size.

Click to expand...

vristang - Doesn't the computer do the 'calibration'? Ford doesn't actually calibrate their meters to the injector, right?

5spd GT said:

vristang - Doesn't the computer do the 'calibration'? Ford doesn't actually calibrate their meters to the injector, right?

Click to expand...

When a component is 'calibrated' 2 things need to be dialed in.
The sensor output
The ecu Transfer

This applies to the ACT, ECT, MAP/BAP, MAF, etc.
The output scaling of the sensor must be known.

When Ford calibrates a MAF meter, it is done on a 'flowbench'
The meter has a specific amount of air sent through it, then the output of the sensor is modified.
Then they move on to another airflow level, and check the sensor output there.

This verifies that the MAF meter output is KNOWN for specific amounts of airflow.


Then the ecu needs to needs to know what the output of the meter is going to be.

There are separate settings in the ecu for the injector size.
A Ford MAF is only calibrated for use with a specific ecu.

Injector calibrations only exist in the Aftermarket MAF world.


Another way to look at it...
The MAF reads airflow and outputs voltage. It is basically translating from the language of airflow, to the language of volatge.
Then the ecu recieves the voltage language, and translates that back into airflow.

There are 2 translation steps there.
If the 2 translations are not EXACTLY the same, then 'miscommunications' will arise.
This is a Calibration in the truest sense of the word.

What the aftermarket does to compensate for Injector size is more of a 'Scaling'

5spd GT said:

vristang - I know you know these things.
So what if you had a 150mm MAF and a stock MAF with a calibration of 19lb injectors.
Would there be any kind of con with the huge MAF at all to to ECU?

Click to expand...

This is a VERY good question.
I have yet to fully explore the affects of this.

Here is what I suspect I will find when I do...
The MAF meter tells the ecu 2 main things. How much air is flowing (duh...), and how hard the motor is working (LOAD).
The engine Load can be thought of as 'driver demand', as it is influenced by throttle position. Or think of Load as a precentage of possible airflow for a given CID and RPM.

Load is where the ecu MAY get confused with larger meters.
Load is used when fine tuning the Ignition Timing and Fuel Injector Pulsewidth.
In theory, both of these things can be corrected pretty easily.
Reset Base timing with a large MAF
The Adaptive Strategy will help dial in the AFR.

How much of an impact will this have, if any?
I have no idea...

To explore this, we would need to look at all the Load tables in the ecu, and make note of how error in Load would affect the output of the tables.
I just haven't gotten around to it...

jason

I posted the following on another forum a couple of days ago...
It should help...




What you are missing is that Ford actually calibrated the MAF output,
and the aftermarket companies re-scale the MAF output.

Here is my attempt to explain things...

With a stock Ford application the MAF meter is calibrated to have a specific output voltage for a given airflow. The voltage output of the MAF meter is called a MAF Transfer.
(The MAF Transfer is basically a look-up chart that the ecu uses to interpret the voltage that the MAF meter is outputting. The ecu will recieve a voltage of 2.2v, then look at the MAF Transfer to see what airflow 2.2v corresponds to.)
Notice there is NO mention of injector size there...
The fuel injectors have their own settings, called the Injector Slopes.
The MAF Transfer and Injector Slope settings are very separate from eachother.

The aftermarket meters...
Most of the time when larger injectors are needed on a Mustang, the owner doesn't want to mess around with changing the Injector Slope settings in the ecu.
(Actually, 'back in the day' the tuning options were more limited, so messing with the ecu settings wasn't really an option for the average enthusiast.)
So in order to accomodate the Mustang enthusiast, the aftermarket developed what they call 'calibrated' MAF meters, which will allow larger injectors and MAF than stock without need to re-tune the ecu.

How does it work?
Let's say you want to run a C&L 73mm and 24Lb injectors on an A9L (stock 19's & 55mm MAF)
The 24's are roughly 26% larger than the 19's. That means that for any given pulsewidth, 26% more fuel will be flowing.
((24/19)-1) * 100 = 26.3%
In order to keep the same AFR (as you would see with all stock components on an A9L), the voltage ouput of the MAF meter must be changed by 26%.
This will essentially TRICK the ecu into providing roughly the correct injector pulsewidths.
Also, a similar adjustment needs to be made due to the size increase of the MAF meter itself; 55mm to 73mm in this case.
Note that you are giving the ecu WRONG information, in hopes of getting the right answer. A 'calibrated' MAF meter is basically saying that 2 wrongs DO make a right.

I won't get into what this does to the LOAD calculation...


Summary...
I guess that is the long way of saying that Ford doesn't calibrate its MAF meters to an injector size. Ford calibrates MAF meters for an ecu.

It should also be noted that when you buy a 'calibrated' MAF meter, not only must that meter be used with the size of injector for which it was 'calibrated' for, but also for the ecu it was 'calibrated' for...
A C&L/PMAS/etc. MAF meter is configured for a very specific ecu/injector combo.


hope that made sense,
jason

Good stuf, thank you Jason, very helpful, you actually know why X does Y

When ever I have questions, I'll revert back to this or you, JT, etc.

Quote:
Does this mean that the LMAF is calibrated to a 36lbs/hr injector?

Nope. Injector size has nothing to do with MAF calibration on OEM Ford MAF's. Injector size is programmed into the EEC.


Quote:
If a MAF is calibrated for the max HP of an engine, why wouldn't all companies calibrate their MAFs for 10,000 horsepower so a person wouldn't have to recalibrate it?

One word: Resolution. The higher the metering capability of a MAF, the less resolution the meter has.

Resolution - basically, it has to do with airflow vs. MAF voltage. Two factors affect it: Physical size of the MAF, and injector size it's calibrated for. For example:



(all numbers are hypothetical and just to describe resolution)



Meter "A" - Can flow up to 800 cfm. Calibrated for 19# injectors

Meter "B" - Can flow up to 1000 cfm, calibrated for 42# injectors



Typical MAF airflow during normal driving will range from 50-200 cfm. This is the same no matter what MAF you are using.



Now, Meter "A" flows 800 cfm at 5v. Meter "B" flows 1000 cfm at 5v. 200 cfm difference, big whoop, right? Wrong.



Now, at 1.25v, Meter A flows 200 cfm. At the same 1.25v, Meter B flows 250 cfm. Do you see the trend here? When you start getting into lower voltages/airflow levels, the bigger MAF has a harder time covering the bigger spread of airflow with the set amount of voltage available.



Kinda like fooling with the "mouse" speed on your computer. Set it up to as fast as it goes, and you can easily move from side to side on the screen with a flick of the wrist. Try to select a single letter in a text document at the high speed, though, and it's a whole new ball game. The amount of distance the pointer covers vs the amount the mouse actually moves makes it very difficult to define exactly where you want to be when it is a very small area. Set the mouse speed to slow, and you can easily select what you want.

Hopefully this makes sense for you. If not, I'll try again. Posted by 93cobra#2771 from CORRAL.NET.

facemelter-
The above is assuming that the MAF Transfer is a linear curve.

The MAF Transfer isn't linear, and in fact has more datapoints in the 'low flow regions' of the curve.

I don't have any MAF curves to post here at work, but I'll find something to help explain this when I get home.

The affect isn't as sever as what '93Cobra#2771' has made it out to be.

Can you post a link (or pm me) to the thread you found this in?

jason

Wait i just relized that you also posted in that forum.Ill link it if you want,but you should know where its at.HAHA

Finally found it...
http://www.corral.net/forums/showthread.php?t=582365
Post #32


By the way...
Post #42 is closer to the way I see the LMAF...
Pay particular attention to posts by this guy (mafpower),
he does know his stuff...


Well, the Corral just crashed on me again, so I'll finish reading through the thread again later...




jason


EDIT:
BTW - The thread I linked to is an excellent thread for folks looking to learn about MAF meters.
There was a ton of info discussed there!!!