MAF meter help
08-19-2010, 06:29 PM
#11
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
No problem...
I really don't want to sound like a broken record here, however you really should consider using the stock MAF for your car. There is no performance benefit at all to be had from the 90mm unit, and in fact with a mail-order tune there may be a downside beyond dialing in low load/rpm drive-ability.
I really don't want to sound like a broken record here, however you really should consider using the stock MAF for your car. There is no performance benefit at all to be had from the 90mm unit, and in fact with a mail-order tune there may be a downside beyond dialing in low load/rpm drive-ability.
08-19-2010, 07:25 PM
#13
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Only if your engine consumes so much air that the stock 80mm MAF cannot properly meter it--as I said above the stock '02 MAF is good to over 400fwHP.
Using a bigger MAF than needed means that the entire operating range of the engine will be using only a fraction of the MAF'e metering range--this means that the MAFs ability to precisely report airflow will be lessened. Precision is important as you might expect.
In the chart shown below the maroon line represents the transfer function of the 90mm Lightning MAF, the pink line the transfer function of your stock MAF. The dashed horizontal shows the maximum amount of air your n/a engine could possibly consume.
You can see that by using the 90mm MAF the usable voltage range is 0.0 to 3.7V or so, and that in the last of the range the slope becomes quite steep.
In contrast, the stock MAF usable range is 0.0 to 4.4V, and much less steep (meaning each voltage "step" is a more precise measure of air flow).
Also of note is that there is no way an n/a 2V is going to "peg" the stock MAF, and that is the only reason for upgrading--bigger is not always better...
Using a bigger MAF than needed means that the entire operating range of the engine will be using only a fraction of the MAF'e metering range--this means that the MAFs ability to precisely report airflow will be lessened. Precision is important as you might expect.
In the chart shown below the maroon line represents the transfer function of the 90mm Lightning MAF, the pink line the transfer function of your stock MAF. The dashed horizontal shows the maximum amount of air your n/a engine could possibly consume.
You can see that by using the 90mm MAF the usable voltage range is 0.0 to 3.7V or so, and that in the last of the range the slope becomes quite steep.
In contrast, the stock MAF usable range is 0.0 to 4.4V, and much less steep (meaning each voltage "step" is a more precise measure of air flow).
Also of note is that there is no way an n/a 2V is going to "peg" the stock MAF, and that is the only reason for upgrading--bigger is not always better...
Last edited by cliffyk; 08-19-2010 at 07:42 PM.
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