# airflow metering



## natoman (Oct 18, 2005)

Greetings!
Question here, around town here, must folks runing turbod factory sr20 will run their airflow metering after the turbo between the intercooler and the throttle valve and not as I've seen at the intake of the turbo, is this safe?
I understand that if one should "blow through" the airflow metering this will cause erroneous air readings.
Please advise.
Appreciate any data.

Nate.


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## wes (Apr 30, 2002)

natoman said:


> Greetings!
> Question here, around town here, must folks runing turbod factory sr20 will run their airflow metering after the turbo between the intercooler and the throttle valve and not as I've seen at the intake of the turbo, is this safe?
> I understand that if one should "blow through" the airflow metering this will cause erroneous air readings.
> Please advise.
> ...


This is called a blow through setup and is becoming more common. The MAF will provide accurate readings although sometimes people have to mess with MAF placement. It should be away from the TB and the BOV should be placed before the TB if you are running it to atmosphere. Do some searches on"blow through" setups and you will find more information.


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## natoman (Oct 18, 2005)

Thank you for advise, will do some research and see about it, my buddy is running a z32 a/f metering with a JWT ECU with 370cc injectors and he's having trouble running too rich.

Nate.


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## wes (Apr 30, 2002)

natoman said:


> Thank you for advise, will do some research and see about it, my buddy is running a z32 a/f metering with a JWT ECU with 370cc injectors and he's having trouble running too rich.
> 
> Nate.


Well that is likely not a result of the MAF placement.


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## el eloy (Aug 14, 2005)

be carefull with the blow thru as this will put much more stress on the MAF.


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## natoman (Oct 18, 2005)

My understanding is that the airflow metering will take measurements of the incoming air into the motor and make necessary adjustments in the fuel but if being OEM that means airflow going into the engine being pulled via vacum force, but if one uses the airflow metering after the turbocharged air being pushed through, shouldn't this cause more air being read by the airflow metering resulting in a bunch more fuel? 
Nate.


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## wes (Apr 30, 2002)

natoman said:


> My understanding is that the airflow metering will take measurements of the incoming air into the motor and make necessary adjustments in the fuel but if being OEM that means airflow going into the engine being pulled via vacum force, but if one uses the airflow metering after the turbocharged air being pushed through, shouldn't this cause more air being read by the airflow metering resulting in a bunch more fuel?
> Nate.


It doesn't work that way. It sees the same either way, weather it is being boosted through or the turbo is sucking the same amount of air through it. AFAIK the MAF wearing out more quickly is kind of unproven at this point. Blow through is something that people recently started doing. There are also other MAF's that are better suited for this application than others. 

The real question here is why would you want to run blow through? There are more advantages (that I know of) to a draw through/recirc setup.


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## el eloy (Aug 14, 2005)

wes said:


> It doesn't work that way. It sees the same either way, weather it is being boosted through or the turbo is sucking the same amount of air through it. AFAIK the MAF wearing out more quickly is kind of unproven at this point. Blow through is something that people recently started doing. There are also other MAF's that are better suited for this application than others.
> 
> The real question here is why would you want to run blow through? There are more advantages (that I know of) to a draw through/recirc setup.



wes, some MAF's tend to be kinda shitty example bosch MAF, many if the cars with bosch motronic ECU have this MAF which is the majority o the vw's and 2002-2003 spec v that i know of, this MAF's tend to break easily, they break even N/A, now imagine when they push 8psi to them?? before the turbo the air is yet to be compressed so there is really not much of a stress to the MAF, perhaps some other MAF's can work better with the blow thru, but as long as you have a bosch motronic ECU your best bet would be staying away from it.


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## wes (Apr 30, 2002)

el eloy said:


> wes, some MAF's tend to be kinda shitty example bosch MAF, many if the cars with bosch motronic ECU have this MAF which is the majority o the vw's and 2002-2003 spec v that i know of, this MAF's tend to break easily, they break even N/A, now imagine when they push 8psi to them?? before the turbo the air is yet to be compressed so there is really not much of a stress to the MAF, perhaps some other MAF's can work better with the blow thru, but as long as you have a bosch motronic ECU your best bet would be staying away from it.


I agree on the VW MAF's. The MAJORITY of the Nissan MAF's including the 04 Spec V's use an MAF that can be used just fine in a blow through setup. Most of the blow through Nissan guys are using OEM Nissan MAF's in their applications. SR20, 300ZX, Q45, and the Ford Cobra and Lightening MAF's. The 02/03 QR's got the short end of the stick in many ways.....


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## natoman (Oct 18, 2005)

Well most guys are running blow through around here, I think it's due to this blow through being the less costly option when they use the factory a/f metering and just pressurize the crap out of it.
I believe in pull through a/f metering set up.

Nate


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## wes (Apr 30, 2002)

natoman said:


> Well most guys are running blow through around here, I think it's due to this blow through being the less costly option when they use the factory a/f metering and just pressurize the crap out of it.
> I believe in pull through a/f metering set up.
> 
> Nate


I also prefer draw through, but isn't draw through and blow through about the same amount of $$$ and work when it comes to Nissan turbo setups?


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## natoman (Oct 18, 2005)

Well the cost varies if when using pull through there's an aftermarket air flow metering like Z32, but I've mostly seen factory a/f's. and relatively low cost set ups fine tuned to put 13.6's quarter miles average.

Nate.


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## wes (Apr 30, 2002)

natoman said:


> Well the cost varies if when using pull through there's an aftermarket air flow metering like Z32, but I've mostly seen factory a/f's. and relatively low cost set ups fine tuned to put 13.6's quarter miles average.
> 
> Nate.


How does the MAF setup have ANYTHIGN to do with 1/4 times? Also the MAF reads the same regardless of where you place it.... The issue here is weather or not the MAF you want to use can support the power you are looking to make.


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## spdracerUT (Jun 11, 2002)

one thing to consider about MAF placement in a blow-thru setup, air flow through a pipe is not always uniform. So ideally, you need a straight section before the MAF. For example, if you put it right after a bend, the flow of air across the cross-section of the pipe is not uniform, and you won't get an accurate measurement; so depending on where the actual hotwire element is located in the pipe, you'll get different readings.


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