here's what i'm running right now..306 with trick flow heads cam and intake... powerdyne supercharger..24 lbs injectors.. 65mm tb..headers x-pipe and flow masters..i have a fmu and a extra fuel pump (external).. i want to upgrade my fuel system and then maybe change my pulley to get more boost.. only at around 5 lbs right now.... i just got a 70mm tb and found a good deal on some injectors..44 or 42's... now what size maf should i go with... also will i have to buy a maf for the injectors or will i need to have it calibrated to the new injectors..
how do I pick what size maf to get
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BlackVert
15 Year Member
I am of the opinion that it is better to get the smallest MAF you can that will flow the amount you think you will flow. The reason is that, the larger the maf, the larger the granularity, which means that the difference in the amount of air represented by 2 adjacent voltages from the MAF is larger on a larger MAF than it is on a smaller MAF. This results in the computer having a harder time really knowing just how much air is coming in, which can result in less accurate injector pulsewidths and load calculations.
At least, that is my opinion.
That said, with a supercharger, something along the lines of a 90mm LMAF would probably be a good choice. Either that, or one of those new MAFs with multiple sensor elements that are supposed to give a very accurate reading.
As to calibrating the MAF for the injectors. While it is better to have them so they can work together without a tune, a supercharged application really should be tuned because of the way the timing curves and load calculations should be tweaked for a forced induction setup. Having them calibrated so they can work together really only buys you the ability to start the car and limp home should the computer decide to go into safe mode for some reason and the tune is lost. It also allows you to drive it to the tuner for the initial tune.
Again, just some opinions from a random guy on the internet.
At least, that is my opinion.
That said, with a supercharger, something along the lines of a 90mm LMAF would probably be a good choice. Either that, or one of those new MAFs with multiple sensor elements that are supposed to give a very accurate reading.
As to calibrating the MAF for the injectors. While it is better to have them so they can work together without a tune, a supercharged application really should be tuned because of the way the timing curves and load calculations should be tweaked for a forced induction setup. Having them calibrated so they can work together really only buys you the ability to start the car and limp home should the computer decide to go into safe mode for some reason and the tune is lost. It also allows you to drive it to the tuner for the initial tune.
Again, just some opinions from a random guy on the internet.
Like all the guys said above 
however
Stepping up from 24's to 42's and a larger meter
You wanna think about how things are gonna be different from how
you are doing things now
For inj's as large as you are talking about ..........
the fmu is not going to work very well and drivability issues will
almost be a given
You need a meter that will deal with the airflow the blower will supply
for now and the additional airflow from your desire to up the boost
I guess you are using the OEM meter
If so ... it will peg out
I'd dump the fmu and select a meter that will handle the airflow
like the other guys said
You then need to have a tuner check to make sure you don't peg
the meter of your choice and he will dial in the proper amount of
fuel based upon the larger inj's
Bottom Line ... with inj's that large
You won't be able to get idle and low load driving conditions such as
when you cruise around town to work very well because the mechanical
method of tuning (meter caled for a certain size inj, adj fpr, and fmu)
just can't compensate for all that fuel when conditions call for a small
amount
Grady
however
Stepping up from 24's to 42's and a larger meter
You wanna think about how things are gonna be different from how
you are doing things now
For inj's as large as you are talking about ..........
the fmu is not going to work very well and drivability issues will
almost be a given
You need a meter that will deal with the airflow the blower will supply
for now and the additional airflow from your desire to up the boost
I guess you are using the OEM meter
If so ... it will peg out
I'd dump the fmu and select a meter that will handle the airflow
like the other guys said
You then need to have a tuner check to make sure you don't peg
the meter of your choice and he will dial in the proper amount of
fuel based upon the larger inj's
Bottom Line ... with inj's that large
You won't be able to get idle and low load driving conditions such as
when you cruise around town to work very well because the mechanical
method of tuning (meter caled for a certain size inj, adj fpr, and fmu)
just can't compensate for all that fuel when conditions call for a small
amount
Grady
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