MAF after turbo?

[Alex86na2t]

It would work fine as long as the air tempature the maf is exposed to isn't greater than the normal temp of the maf wires. You may experience some problems in high boost (when your air temps get high). Read up on how a maf works, it should give you a lot more theory to work with.

[j30_vg33et]

Yeah, it really seems to be an issue of not exceeding the temp of the "hot-wire". I'm using a J30 Maxima MAF. Though it's pinned, so it's time to upgrade to a Z32 or the like.

I've got a Ford F150 and Pro-M and unit laying around, but the cals are kinda smacked on them, so I'd prefer to use two identical units.

Anyone have suggestions for where to get a good price on a Z32 MAF or two?

[t70]

got mine on ebay for $112 i think

[Jason84NA2T]

j30_vg33et wrote: Yeah, it really seems to be an issue of not exceeding the temp of the "hot-wire". I'm using a J30 Maxima MAF. Though it's pinned, so it's time to upgrade to a Z32 or the like.

I've got a Ford F150 and Pro-M and unit laying around, but the cals are kinda smacked on them, so I'd prefer to use two identical units.

Anyone have suggestions for where to get a good price on a Z32 MAF or two?

tt.net and ebay

which pro-m unit do you have? they only sold like 300 varieties.

[Bernardd]

`

[Alex86na2t]

t70 wrote: right... ok.. because the air density is different as boost comes in, the maf meteres less than is actually going through. In fact i wonder if it would even see the difference between 5psi and 6 psi? Thanks a lot guys... i'll continue tuning with a flow through and not a blow through!

Ok maybe you need to know how a MAF works...........
In the MAF there is a wire (or several in our case). The ecu sends electrical current through this wire, the wire becomes hot because of this current. The passing air over it absorbs some of this heat. The more air passing over the wire the more current the ECU must send to maintain the wire tempature. So, the ecu measures how much current it takes to keep the wire at a specified tempature, and from that, it is able to calculate the exact amount of air enterering the engine.

[j30_vg33et]

Is there a difference between the Z32 TT and N/A meters?

Oh, and the Pro-M I've got is this huge beast that I couldn't fit in my car if I started cutting.
Model: 80R 2001 Lightning
SN:....
Calibration: 96 GT 24 C

I'm sure I've got the flow vs. voltage sheet laying around too if someone wants to buy/trade.

Also, I've got (2) cam gears + (1) crank sprocket + cover washers from a 97 pathfinder if anyones interested in swapping to the 100k belt.

[t70]

Ok maybe you need to know how a MAF works...........
In the MAF there is a wire (or several in our case). The ecu sends electrical current through this wire, the wire becomes hot because of this current. The passing air over it absorbs some of this heat. The more air passing over the wire the more current the ECU must send to maintain the wire tempature. So, the ecu measures how much current it takes to keep the wire at a specified tempature, and from that, it is able to calculate the exact amount of air enterering the engine.

THANKS!!

and yes the z32 mafs are the same (na and turbo)

[j30_vg33et]

Lots of stuff to read. The bottom line is that lots of people are blowing through w/o any issues.

From the Pro-M people: (http://www.massairsystems.com/Q&A.htm)
> What is the difference between a blow-through calibration and a draw-through?
> -Actually nothing. What does make a difference is what is in front of the meter (elbows, straight pipe, air filters, etc.)
> Obviously, any Pro-M style meter with a filter directly attached to the front is a draw through.
>
>Why have I heard that blow-through meters "peg" sooner than draw-through meters?
> -They don't. What actually happens is that most meters set up in blow-through configurations have elbows in front of the MAF,
> causing the meter's calibration to be off. A properly calibrated blow-through meter will not "peg" any sooner than a draw-through style meter.

MAF operation description from an industry journal:
http://www.wellsmfgcorp.com/counterpoin ... int3_2.pdf

Four good articles from of all places, yikes, mustang people...
http://www.mustangworks.com/articles/el ... Blues.html
http://www.modulardepot.com/?show=articlesdet&aid=37
http://www.modulardepot.com/?show=articlesdet&aid=24
http://www.modulardepot.com/?show=articlesdet&aid=21

Enjoy.

[acabtp]

in theory it would work while being used as blow through, because as the name implies, it is a MASS air flow sensor. its readings are calculated by measuring the ΔT of the wire, and air flowing at higher pressure (more mass/second) will cause a greater change than air at lower pressure (less mass/second). the MAF knows nothing about the pressure of the air it is metering, so this larger ΔT of the wire will be interpreted as greater air flow, just as the larger ΔT of the wire when at WOT than part throttle is interpreted as greater air flow.

however, the MAF is designed to work with ambient air temperatures of maybe -40°F to 150°F. after the turbocharger, the intake air temperatures may be much higher than what it can handle, or make accurate measurements at.

so, in the end, someone's gonna have to try it. jon jewell was thinking about going to this setup as well. maybe ask him if he's gotten anywhere on that.

[t70]

thanks for all the info boys... i'll have to read those pages at some point this weekend...

[crowbar]

The MAF has a temp compensation resistor. So up to a point, it can still accurately measure mass regardless of the boosted pressure temp. It would still be a good idea to have an intercooler between the turbo and MAF. Also, oil blowby from the turbo might harm the maf.

But I do not see any real advantage and some potential disadvantages.

[Jason84NA2T]

crowbar wrote: The MAF has a temp compensation resistor. So up to a point, it can still accurately measure mass regardless of the boosted pressure temp. It would still be a good idea to have an intercooler between the turbo and MAF. Also, oil blowby from the turbo might harm the maf.

But I do not see any real advantage and some potential disadvantages.

I would concur, if you have a compressor side oil seal leak it'd be no fun.

I guess the advantage would be in having less restriction at the inlet, but you will get a small pressure drop through the maf. My car does not get super excessively rich from blowing off metered air, so it would not be a "fix" for me for that....

[MachZ]

I've tried both on my Maxima and noticed when setup for the blow through the readings were higher according to my SAFC... however... my intake pipe was pretty much junk (i.e. the size change between the turbo and intake was a change of around 1.5 inches to 3 inches (small to large) with crappy pressure bent pipe and it was poorly done).

Anyways, I would think that the temperature difference between ambient and when compressed would cause different readings alone... but I could be wrong.

[Grr]

we have tried it,
http://gnttype.org/techarea/engine/mafrelocate.html
and the throttle response was a bit quicker, all around snappier and idled better too. this is especially true the longer the induction pathway is. as long as the air temp sensor is reading the same temp as the maf is seeing, the computer is able to compensate. anyway if your running a front mount it shouldnt be that much hotter air anyway.
Gary