Georgia_boy
02-20-2007, 06:45 AM
Found this on another site and thought it would help someone with there setup along the way. I't may not answer all questions but you get the general idea.:)
MAF SETUP
There are 2 different ways you can set up your MAF, a suck through or blow through. This will also dictate if you’re going to have a blow off valve a bypass valve.
a. blow off valve will relive the compressed air in the atmosphere
b. bypass valve will relive the compressed air back into the compressor
in the pics
1) turbo compressor
2) air filter
3.a) blow off valve
3.b) bypass valve
4) intercooler
5) MAF
6) throttle body
PIC 1
That is the Blow through system, because air is being blown through the MAF. As you can see air enters the air filter, gets compressed by the turbo then the air gets blown past the BOV (blow off valve), through the intercooler, through the MAF, then finally past the throttle body. When the throttle body is shut, it will cause a vacuum in the upper intake manifold. A rubber hose is connected from the upper to the back of the BOV; the BOV will sense this vacuum. Inside the BOV is a spring and valve, on one side of the valve is boost pressure, and on the other side is vacuum. Once the valve senses high pressure on one side and vacuum on the other side, the spring will compress and the valve opens releasing pressure. Once the valve is open it will release the compressed air into the atmosphere. Then when the pressure difference tends towards equilibrium the valve will shut. The BOV works the same as a bypass valve or BPV.
In this blow thru system, the BOV has to be mounted before the MAF. This is because the BOV vents to the atmosphere, if it was mounted after the MAF, the BOV would release air that has been metered, if it vents metered air, then it will throw off the fuel and will make things rich, since the air that should be there isn’t there.
PIC 2
This is a suck through system, because air is being sucked in through the MAF by the turbo. Which one of the differences from a blow thru system.
In a suck thru system the MAF is put in front of the compressor. But the BOV still as to be mounted on the pressure side of the intake pipes, for it to do its job, which now has to be converted to a BPV with the help of that “green” pipe. The BPV can not vent into the atmosphere otherwise it will vent metered air. So it has to vent back into an intake pipe before the turbo and I believe after the MAF because you don’t want to meter air twice.
As far as which setup is better, I hope someone with more tuning insight can answer that. Because I’m sure it will come down to which is more easily tuned. But I like the blow thru system its easier to fab up and the louder “psshh” is a plus too.
MAF SETUP
There are 2 different ways you can set up your MAF, a suck through or blow through. This will also dictate if you’re going to have a blow off valve a bypass valve.
a. blow off valve will relive the compressed air in the atmosphere
b. bypass valve will relive the compressed air back into the compressor
in the pics
1) turbo compressor
2) air filter
3.a) blow off valve
3.b) bypass valve
4) intercooler
5) MAF
6) throttle body
PIC 1
That is the Blow through system, because air is being blown through the MAF. As you can see air enters the air filter, gets compressed by the turbo then the air gets blown past the BOV (blow off valve), through the intercooler, through the MAF, then finally past the throttle body. When the throttle body is shut, it will cause a vacuum in the upper intake manifold. A rubber hose is connected from the upper to the back of the BOV; the BOV will sense this vacuum. Inside the BOV is a spring and valve, on one side of the valve is boost pressure, and on the other side is vacuum. Once the valve senses high pressure on one side and vacuum on the other side, the spring will compress and the valve opens releasing pressure. Once the valve is open it will release the compressed air into the atmosphere. Then when the pressure difference tends towards equilibrium the valve will shut. The BOV works the same as a bypass valve or BPV.
In this blow thru system, the BOV has to be mounted before the MAF. This is because the BOV vents to the atmosphere, if it was mounted after the MAF, the BOV would release air that has been metered, if it vents metered air, then it will throw off the fuel and will make things rich, since the air that should be there isn’t there.
PIC 2
This is a suck through system, because air is being sucked in through the MAF by the turbo. Which one of the differences from a blow thru system.
In a suck thru system the MAF is put in front of the compressor. But the BOV still as to be mounted on the pressure side of the intake pipes, for it to do its job, which now has to be converted to a BPV with the help of that “green” pipe. The BPV can not vent into the atmosphere otherwise it will vent metered air. So it has to vent back into an intake pipe before the turbo and I believe after the MAF because you don’t want to meter air twice.
As far as which setup is better, I hope someone with more tuning insight can answer that. Because I’m sure it will come down to which is more easily tuned. But I like the blow thru system its easier to fab up and the louder “psshh” is a plus too.