mass air meter

[Racin Jason]

well guys,im undecided on which mass air to use,,sct ba 3000 or the 3in pro m blow thru.. can u guys chime in on this please.. dart based 331,76mm looking to make about 700-800 rwhp thanks

[NXcoupe]

You know my vote.

[Racin Jason]

yes i do..i just hate to give up such a nice piece..lol

[93snake]

You know my vote.

Top secret?!? :D

[NXcoupe]

Nope, lol, I vote for the ProM protube. Reason is this, any meter you have to alter the maf transfer function by 40% just to get it to run and drive without being 10 to 1 has issues. They are stellar meters when in a draw thru setup, but when you go to a blow thru system, they suck, plain and simple. The protube excels in that application. I rarely have to alter them more than 10%, while most are good to go and just need tweaking in certain cells. jmho

[facemelter71]

Nope, lol, I vote for the ProM protube. Reason is this, any meter you have to alter the maf transfer function by 40% just to get it to run and drive without being 10 to 1 has issues. They are stellar meters when in a draw thru setup, but when you go to a blow thru system, they suck, plain and simple. The protube excels in that application. I rarely have to alter them more than 10%, while most are good to go and just need tweaking in certain cells. jmho

Was this situation just one or two cars,Bad meter perhaps.Or are all of the SCT meters you have tuned like this? Im just curious. And which one in perticular are you talking about,the BA2600 or 3000 or that 5000 job. I have heard that the 2600 isnt that great fow blow thru.

Is it the transfer function in the light load low volume area?

Im just trying to learn a little.

[NXcoupe]

ba3k and below. The 5k drop in units have worked well in both conditions. more so at lower, but throughout the dynamic range of the meter it is skewed. Has a lot to do with the way the sensor is positioned in the meter and the airflow through it.

[NXcoupe]

And no it was on multiple vehicles, two in the past two weeks, which just made it fresh in my mind. But over the years, quite a few, most from another shop that pushes these meters in blow through setups and they just don't perform well.

[facemelter71]

Is it possible that the severe bends in the pipe before the meter is what would cause the skewed meter reading? You said it is possible that is has to do with where the meter is placed within the housing. I wonder what type of procedure ProM has for tuning the meter since it is easier to setup the transfer function on a blower car VS a draw thru car for SCT.
And I would guess since the BA5K meter gets put in the existing hole of the old meter that THAT perticular housing is correctly set for that meter position despite the bends before the meter. I dont know,maybe Im reading to much into this.

[SCHMUCKINGHAM]

Are any of these new digital meters set up for blow through or are they all draw through?

[Adam@S&MMotorsports]

Is it possible that the severe bends in the pipe before the meter is what would cause the skewed meter reading? You said it is possible that is has to do with where the meter is placed within the housing. I wonder what type of procedure ProM has for tuning the meter since it is easier to setup the transfer function on a blower car VS a draw thru car for SCT.
And I would guess since the BA5K meter gets put in the existing hole of the old meter that THAT perticular housing is correctly set for that meter position despite the bends before the meter. I dont know,maybe Im reading to much into this.

Andy almost every issue I have ever seen with an SCT meter was its location and or the position of a bov in relation to it.:bigthumb

[facemelter71]

Andy almost every issue I have ever seen with an SCT meter was its location and or the position of a bov in relation to it.:bigthumb

Was waiting for you to chime in.

Im just trying to wrap my head around MAF's. I love learning new things that directly relate to the things I am working on. I dont want my meter to be a majic metal tube that air goes through. I want to understand how a volume of air is metered and what can cause an issue. I know that in a perfect world,the MAF should have 3 feet of strait tube in front and behind it for a PERFECT reading. But in a vehicle,that is very unlikely to happen.

When you change a MAF transfer function,lets say for a light load/cruise,you only change that one particular spot on the tranfer function table? Or do you change the hole thing?

[Adam@S&MMotorsports]

Was waiting for you to chime in.

Im just trying to wrap my head around MAF's. I love learning new things that directly relate to the things I am working on. I dont want my meter to be a majic metal tube that air goes through. I want to understand how a volume of air is metered and what can cause an issue. I know that in a perfect world,the MAF should have 3 feet of strait tube in front and behind it for a PERFECT reading. But in a vehicle,that is very unlikely to happen.

When you change a MAF transfer function,lets say for a light load/cruise,you only change that one particular spot on the tranfer function table? Or do you change the hole thing?

I was trying to avoid it actually :lol: The rule of thumb is 3 to 4 times the diameter of the pipe in straight pipe before and after the maf, but you are right that is in an ideal world. As far as the rest of you questions I will answer in extreme detail over the phone or in person, I don't feel like writing a book on here:bigthumb

[facemelter71]

Perfectly fine with me. Ill have to catch you when your not very busy at the shop. You going to be there this Saturday.

[Adam@S&MMotorsports]

Perfectly fine with me. Ill have to catch you when your not very busy at the shop. You going to be there this Saturday.

Every one unless there is an 8.5 race out of town or I'm at the lake:bigthumb

[Blackout]

Every one unless there is an 8.5 race out of town or I'm at the lake:bigthumb

At the lake?...... yeah right, like your going to catch something....lol.. Don't forget the cooler. :D

[NXcoupe]

Was waiting for you to chime in.

Im just trying to wrap my head around MAF's. I love learning new things that directly relate to the things I am working on. I dont want my meter to be a majic metal tube that air goes through. I want to understand how a volume of air is metered and what can cause an issue. I know that in a perfect world,the MAF should have 3 feet of strait tube in front and behind it for a PERFECT reading. But in a vehicle,that is very unlikely to happen.

When you change a MAF transfer function,lets say for a light load/cruise,you only change that one particular spot on the tranfer function table? Or do you change the hole thing?

Depends on what is happening at that voltage reading at that point on the table. Usually concentrating on one cell will cause a skew in the data points and give you a crappy curve on the graph, if you get too out of whack with it, you'll have a car that will shut off at that particular point on the data map.
All a maf meter does is send a voltage signal to the computer that the computer interprets as a kg/hr reading of mass of air. mass and weight are two completely different things, but that's a physics lesson and we'll skip that.
If the voltage the maf meter sends to the computer incorrectly represents the actual amount of air that is getting through to the engine at that instant, the computer will either inject too much fuel or not enough. Adjusting the transfer function to correctly represent the amount of air going into the engine is the goal.
Airflow through a meter is another physics lesson of fluid dynamics. What ProM does is alter the electronics in the meter to give the computer a voltage signal that accurately represents the amount of air going through the tube at that time. They can set up their function in the meter so that it takes into account the bends before and after the maf. A blow off valve can affect part throttle and idle issues with a car but when the issue is wot, the bov is closed and shouldn't affect the flow through the tubing.
Hope this helps some. There is no secret 'magic' to this stuff, it's just physics and simple electronics. I have done this for years, and ProM has usually had really good meters that require very little manipulation to get them right. They had a period right before they went out of business where everything they shipped was crap. The new ProM has risen from their ashes and is once again turning out a good product. Jmho, everyone has their own.

[NXcoupe]

Oh, and to the OP, iirc your voltage at 500 hp was nearly 4.7 volts, which means if you get closer to your hp goals your meter will peg. I was just trying to suggest something that would help you achieve your goals and that I know will work easily for you.