First top mount single turbo 370Z

98intrigue · 05-12-2011, 11:35 PM

Quote:

Originally Posted by Red__Zed

You figure the TB issue is related to using different intake tract lengths?

That is the culprit to the MAF maxing out, but we are not sure why it threw a code for a bad throttle body. It would make sense that since the driver's side MAF was getting about 20% more air than the passenger side MAF, maybe the driver's side throttle body was trying to compensate and open more than then it through a code and went into limp mode? But then why after hooking it all back together about 2 hours later, it ran fine...even after probably 5 dyno pulls?

Quote:

Originally Posted by Ryan@prosportGauges

im still wondering why not mount the MAF's before the Split to each TB!

Because then Shawn would have to modify both intake piping and relocate the BOV... if the upgraded MAFs don't work out, your idea will be the next step.

Prosport Gauges · 05-13-2011, 09:41 AM

Quote:

Originally Posted by 98intrigue

That is the culprit to the MAF maxing out, but we are not sure why it threw a code for a bad throttle body. It would make sense that since the driver's side MAF was getting about 20% more air than the passenger side MAF, maybe the driver's side throttle body was trying to compensate and open more than then it through a code and went into limp mode? But then why after hooking it all back together about 2 hours later, it ran fine...even after probably 5 dyno pulls?

Because then Shawn would have to modify both intake piping and relocate the BOV... if the upgraded MAFs don't work out, your idea will be the next step.

You can plum the BOV further down stream :P

98intrigue · 05-13-2011, 10:16 AM

Quote:

Originally Posted by Ryan@prosportGauges

You can plum the BOV further down stream :P

But it looks "cool" where it is, haha.

ChipsWithDips · 05-13-2011, 04:15 PM

Quote:

Originally Posted by 98intrigue

That is the culprit to the MAF maxing out, but we are not sure why it threw a code for a bad throttle body. It would make sense that since the driver's side MAF was getting about 20% more air than the passenger side MAF, maybe the driver's side throttle body was trying to compensate and open more than then it through a code and went into limp mode? But then why after hooking it all back together about 2 hours later, it ran fine...even after probably 5 dyno pulls?

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.

Quote:

im still wondering why not mount the MAF's before the Split to each TB!

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

jran76 · 05-13-2011, 04:44 PM

Quote:

Originally Posted by 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.

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....

A4RingedONE8T · 05-13-2011, 08:22 PM

Quote:

Originally Posted by 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.

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 · 05-14-2011, 06:16 AM

Quote:

Originally Posted by 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.

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?

Boost_lee · 05-14-2011, 01:44 PM

i want 4.8 psi now!

370ZDreamer · 05-18-2011, 02:17 PM

Quote:

Originally Posted by 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.

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 · 05-18-2011, 03:24 PM

Quote:

Originally Posted by 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?

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 · 05-18-2011, 04:12 PM

Quote:

Originally Posted by 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?

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 · 05-18-2011, 04:58 PM

Quote:

Originally Posted by Nixlimited

I assume the injectors in the left bank of cylinders will be pulsed according to the reading of MAF 1 and the injectors in the right bank of cylinders will be pulsed according to the reading of MAF 2. One of the drawbacks of 1 MAF is the assumption that air metered by the MAF is equally distributed to the different cylinders. I assume 2 MAFs helps mitigate this issue; however, as we have seen with this project, that does not hold true when the piping is changed. I hate MAFs altogether. Give me MAP metering any day!

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.

Nixlimited · 05-18-2011, 05:41 PM

Quote:

Originally Posted by 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).

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 · 05-18-2011, 06:11 PM

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

05-14-2011, 01:44 PM	#8 (permalink)
Boost_lee A True Z Fanatic Join Date: Feb 2009 Location: SATX Posts: 2,813 Drives: 09 370Z TT 6MT Rep Power: 31	i want 4.8 psi now! __________________ My TT Z

05-18-2011, 06:11 PM	#14 (permalink)
jran76 Base Member Join Date: Nov 2009 Location: Plano, TX Posts: 74 Drives: 09 G37S Sedan 6MT Rep Power: 17	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 __________________ 2009 G37S Sedan-6MT: Advan / Volk / Tein / SPC / Invidia / Cobb / K&N Last edited by jran76; 05-18-2011 at 06:13 PM.

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