Did some logs yesterday and it seems my stock maf's are almost maxed out right at 17psi with the gtm tt kit. 3" intake tubes. GTM knew that, that's why they went with bigger intakes..

If any of you need upgrades, I can get you a good deal on our Z-MAFs.

I plan to be pushing 18psi in the next couple of weeks. I'll let you know how my setup works with the tall maf stand offs

Since this got bumped up today ill post something I noticed.

Does anyone see that even though the MAF voltage is not maxed out the flow rate max's out within Uprev? Is this a limitation to Uprev or the ECU itself? I want to say off the top of my head that the max flow it will read is something like 268 or something like that, but there is still plenty of voltage to go.

I can verify that that's the MAFgm's I'm seeing NA (268.79) with MAF volts mid low 4's 4.2's-3's

Yeah and it does not increase if you go with a higher voltage than 4.2.I dont know if this is a limitation to the logging software in Uprev or what.

Mine are right at 4.8v right at 17psi in the upper rpm range..

But what does your flow rate do right around there? Mine maxx's out even though there is still breathing room in terms of voltage.

More than happy to post up my log if you guys have the program to view it.?

i got it...

Post it up its all done in CSV format anyway. Or if you could confirm that lets say above 4.5 volts that the maf flow rate continues to rise after 4.5 volts?

Trying to upload but it keep coming back saying invalid file.. ideas?

screen shot or pic off your phone

I wouldn't expect mine to be maxing at 5 NA but heres mine at 4.9Vlts and the 268.79 MAFgm's


MAS A/F -B1 (V) 4.26

MAS A/F -B2 (V) 4.49

B-FUEL SCHDL (ms) 19.7

MAF GM/S (gm/s) 268.79

Yeah that 268.79 will stay there at like anything after 4.1 volts if I recall correctly. I dont know if thats a limitation on the car or in the uprev package. I guess the way to find out is call and ask them about it.

I suppose this is a legitimate question, have any of you guys tried running the MAF's post turbo (on the turbo intakes / no pressure side) opposed to the intercooler charge piping? I know the part number on the R35 MAF and Z34 MAF is the same and if i recall correctly R35 guys are making about 750AWHP on 3" MAF housings and 850whp on 80mm housings. on a RWD platform that should translate to about 5% more whp.

You're suggesting switching to a draw-through as opposed to blow-through? That's going to require the BOVs to be plumbed back in pre-turbo since otherwise they'd be venting metered air and you'd get a rich hiccup every time the BOV opens.

It shouldn't because the Only time bovs are open is when you off the throttle. This is how my turbo talin is setup from the factory..time to get in the lab..and make something up

That's a well-documented problem that most draw-through maf-based cars (Isn't the Talon MAP-based?) face with a BOV vented to atmosphere. If you vent metered air, the computer doesn't know that the air is gone and you swing rich for a second between shifts or when you let off throttle. It just stumbles a bit in between shifts.

Plus, are we worried about the different air density between the air at the maf and the post-turbo, post-intercooler air? Isn't this one of the (many) problems with the maf pocation on the Stillen kit?

No the talon runs the 3in gm maf with a after market atmosphere bov and it don't have any issue. I guess no one will know till they try it...I'm not to worried about cuz I'm at 10psi and still have a full volt left be4 it's at max but I would like to try just to see what happens

But as I look the r35 maf's are in the same spot as ours. When I went to 3in and tall maf's it fixed all my problems. I think everybody just need bigger pipe

yeah except R35s have draw through, instead of blow through 1,

i would personally not run BOV's and just install some Turbosmart or Synapse bypass valves (plumb back)

ur right they are i just said there in the same spot....and BOV to Bypass is up to that person. me personlly have had to many turbosmart things fail on me to use them...

R35s also switch to speed density tuning under load. The MAFs are only used under low load because speed density tuning isnt accurate at low flow rates.

Also if you are only sucking through the mafs they will not be able to read as high as when you are blowing through them. I believe that was discussed earlier on in this thread with phunk.