Blow through vs draw through MAF

[mrk1]

Simple question, whats the pros and cons of each style. Looks like exsisting kits are all blow through.

[King Tut]

I can't see any advantage to mounting a MAF prior to the turbo. I want the MAF as close as possible to where the air enters the engine.

[spitfire481]

My 400hp gti runs a 4" maf housing with oem sensor pre turbo. Zero issues. Then people run blow through maf's on many turbo cars and have zero issues as well. Guess there's no real right answer

[mrk1]

correcting my original post, the AVO kit is a draw through with the stock air box

[86_ZN6]

works turbo kit also uses stock maf and airbox. zero issues

oem look and will be carb legal

[sw20kosh]

Blow Through MAF has one advantage (if it is placed post intercooler) because the IAT sensor is integrated with the MAF sensor: IAT measures air temp properly and the tune can be adjusted based on IAT

[ptuning]

Advantages of a Blow-thru MAF:

1) You can run a true BOV without worrying about recirculating it. This is a very big deal for most turbo set-ups.
2) If you pop-off a coupler or intercooler pipe while boosting, the engine will still run and allow you to "limp" home or at least to the side of the road.
3) Air temp compensation for fueling and timing can be applied as it is metering actual air temp post-intercooler.
4) No need to cut or extend MAF wires, depending on turbo intake location.

Advantages of a Draw-thru MAF:
1) Technically speaking, all air going into the engine, including through the valve breather and PCV is metered and accounted for, but this is very minor and does not affect real-world tuning. Blow-thru would never pass emissions at the OEM level.
2) MAF doesn't get oily if your turbo seals decide to take a dump. Again, not a really big deal unless you plan on using an eBay turbo.
3) You can run a 3.5" MAF housing without having a ridiculously huge looking upper intercooler piping. Not a big deal now either, because you can tune SD blending to prevent MAF overrun on big HP set-ups.

In the end, you'll find most tuner shops and manufacturers going with the Blow-thru MAF route, because the advantages clearly outweigh any perceived disadvantages. Hope this helps.

[sw20kosh]

Originally Posted by ptuning

Advantages of a Blow-thru MAF:

1) You can run a true BOV without worrying about recirculating it. This is a very big deal for most turbo set-ups.
2) If you pop-off a coupler or intercooler pipe while boosting, the engine will still run and allow you to "limp" home or at least to the side of the road.
3) Air temp compensation for fueling and timing can be applied as it is metering actual air temp post-intercooler.
4) No need to cut or extend MAF wires, depending on turbo intake location.

Advantages of a Draw-thru MAF:
1) Technically speaking, all air going into the engine, including through the valve breather and PCV is metered and accounted for, but this is very minor and does not affect real-world tuning. Blow-thru would never pass emissions at the OEM level.
2) MAF doesn't get oily if your turbo seals decide to take a dump. Again, not a really big deal unless you plan on using an eBay turbo.
3) You can run a 3.5" MAF housing without having a ridiculously huge looking upper intercooler piping. Not a big deal now either, because you can tune SD blending to prevent MAF overrun on big HP set-ups.

In the end, you'll find most tuner shops and manufacturers going with the Blow-thru MAF route, because the advantages clearly outweigh any perceived disadvantages. Hope this helps.

It is also hard to have a blow through MAF with a PD supercharger system sitting ontop of the engine. =)

[ptuning]

Originally Posted by sw20kosh

It is also hard to have a blow through MAF with a PD supercharger system sitting ontop of the engine. =)

LOL, agreed.

[mrk1]

Thanks ptuning, I tend to like draw through or SD just based on past setups I've built. Obviously both style has pros/cons.