From my understanding, this applies to the position in line of the MAS when forced induction is used.
For a "draw-thru" meter, the meter is IN FRONT of the blower/turbo. Having it here, the air is 'drawn-thru' as it is being sucked in by the impeller and then pushed into the motor.
A "blow-thru" meter has it in line AFTER the blower/turbo. So, the air is sucked in through the air filter, compressed by the impeller and pushed THRU the MAS on it's way to the intake.
I'm sure there are advantages and disadvantages for both but I am not sure what they would be.
For a "draw-thru" meter, the meter is IN FRONT of the blower/turbo. Having it here, the air is 'drawn-thru' as it is being sucked in by the impeller and then pushed into the motor.
A "blow-thru" meter has it in line AFTER the blower/turbo. So, the air is sucked in through the air filter, compressed by the impeller and pushed THRU the MAS on it's way to the intake.
I'm sure there are advantages and disadvantages for both but I am not sure what they would be.
With a drawthrough MAF, the air is metered soon after the filter and before the blower. This setup is usually used with a bypass valve returning the metered air between the MAF and the blower. With a blowthrough MAF, the air is metered after the blower. This setup is usually used with a blow-off valve.
Correct, you need to recirculate the vented air back to the inlet of the turbo, but behind the MAF or you screw up your fuel management.