First top mount single turbo 370Z

ChipsWithDips

Yeah like I said, that MAF on the passenger side bend is not gonna be able to get an accurate reading. Think about it, the flow of air through a bend is not equal across the entire cross section of pipe. There's going to be a gradient of different flows throughout. The MAF only measures flow across it's hot filament which is only a specific point in that cross section. There's no way for it to get an accurate average of the entire cross sectional area.


Here's an example of how flow changes through just 30degrees of bend.



if you did that they would be reading 2x as much flow each.

jran76

I think you pretty much covered it. I really think the intake piping is going to have to be re-done in some way. I don't see any way around it. I honestly think something like the intercooler GTM uses on their SC kit would be the way to go. Of course, then you would have to do something different with the air filter on the turbo.... Easy for me to say....

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2009 G37S Sedan-6MT: Advan / Volk / Tein / SPC / Invidia / Cobb / K&N

A4RingedONE8T

Stock MAF's should be maxing out around 10-12psi, the passenger side MAF, on the radius, is NOT the problematic one. The one on the DRIVER'S side, the one on the straight piece of pipe, is the one that is maxed out. While your drawings may be true, the MAF on the radius is NOT what is causing the issue with Ryan's car. We already have a few different fixes if the upgraded MAF's do not get the car where Ryan wants it, no one needs to worry other than Ryan and myself. The injectors are also too small, they will be maxing out near if not before 500whp. Tuning with the two MAF's, as they are placed, was of no issue.

Mr.Squeeze

The HPX MAF's should work they wont peg. I am curious as to want kind of
injector pulse you guys had with the 600cc?

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Driven Motorsports Single Turbo 7675 T4 1.32 A/R 995WHP 780TQ

Boost_lee

i want 4.8 psi now!

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My TT Z

370ZDreamer

How does Nissan handle the flow from 2 different MAF sensors to begin with? Are there 2 different airflow curves for each MAF?

I am used to tuning Ford and GM cars with a single MAF, but when you change the MAF size or location on either of those applications you just build a new airflow curve for the calibration.

Couldnt you do that with 2 maf's in 1 pipe or is it just one table even though theres 2 MAF's?

ChipsWithDips

The problem is the MAFs would max out their voltage much earlier. Tuning the MAF tables in the ECU just changes how much airflow the ECU interprets the MAF voltage levels as. Doesn't help if you're maxing out the voltage.

Nixlimited

Edit: see post below.

I hate MAFs altogether. Give me MAP metering any day!

As someone else pointed out, 2 MAFs in 1 pipe wouldn't work well because they are sized to handle half the airflow and would max out. Even though you can recalibrate them, it would still be a mess.

jran76

The air from both intakes (and MAF's) all ends up in the same place. They are not divided inside the plenum/manifold, and the runners are in a row down the middle so they are pulling air from both intakes at the same time as it is mixed inside the plenum. The ECU just sees the air flow (voltage) from both MAF's and calculates the two together as the total amount of air going in. If each intake only went to one bank of (3) cylinders, the OP would have to re-do the piping to have somewhat even airflow to each side. Since the air is mixed inside the plenum, they are going to overcome the issue by allowing more airflow on one side than the other, and upgrading the MAF's to handle more airflow/voltage on that one side that has more airflow (really a band-aide for the uneven airflow, but it will work with the way our intake plenum and runners are setup).

Edit: The above is not correct. After looking at some pics and the service manual, it is split inside the manifold, and the ECU is looking at the MAF signals as Bank 1 and Bank 2.

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2009 G37S Sedan-6MT: Advan / Volk / Tein / SPC / Invidia / Cobb / K&N

Nixlimited

Ahhhh, DUH! Not having experience with the innards of the plenum I assumed there was some other reason for the dual MAFs. Editing my post above to not spread false info.

jran76

So, I was wrong. It does look like it is split in some way, and the MAF's are specifically referred to as for "Bank 1" and "Bank 2" in the service manual. I am assuming that there is something to even out the airflow to each side, but not sure what it is.

Here are some good pics of the inside of the manifold. DIY 350zHR Intake Swap

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2009 G37S Sedan-6MT: Advan / Volk / Tein / SPC / Invidia / Cobb / K&N

1slow370

you could put both sensors in one pipe you just need a larger pipe with twice the flow of a single pipe and tweak in the maps. The reduced velocity from the larger pipe will keep the MAF sensors form maxing. <-- also the piping around the problematic sensor could just be bulged out to do the same thing and keep it from maxing. you don't need new MAF sensors you need a new pipe + tune. Also i'm sure his shop already knows all of this so we could all just shut up and wait for it to be finished?

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370ZDreamer

So are the MAF's represented in the processor tables as Bank 1 and 2 or just 1 whole airflow table?

ChipsWithDips

I think you were right the first time, it's not a huge plenum where you can see straight through to the other side, but I've seen myself, shining a flashlight in one throttle body, and peeking in the other, the light is visible(indirectly) from the other side.

Also, I didn't see in your pics, but where are the bank 1 and 2 wideband O2 sensors? If you have them sharing the same pipe after the two banks merge, the ECU will not like that either. It will try to trim one bank slightly, see no difference between the O2s, trim it more, see no difference, etc. until the banks are off by up to 25% or so.

Are you tuning with UpRev? I know with that you can log the fuel trim levels for each bank to check if something like this is happening.