Regal Turbo Build

10sec

I haz dat teddy bear smile.
TCG Premium
Jul 26, 2008
25,942
5,810
ohhh the maf IS maxing out? Yeah, that'll do it. What actual PSI are you running? I don't think anything matters when you max out the MAP now that I think about it, but my scans are from 2009-2010 and are on a computer from 2007-ish so trying to go back and look at them isn't going to happen :rofl:

I'm just having such a hard to remembering if it read over 200kpa or not.

You'll need to get or make one of those pigtails that scale the maf for you. Once I put that on my car I wasn't anywhere near to top of the maf scale and everything was happy.
 

bs009

Making 3800's Great Again
Feb 13, 2014
698
2,129
NashVegas
The MAP is only a 2 bar map so it will range from 0-200kpa. Luckily the PCM almost never uses it so that's not the problem. My car will always show 200kpa at WOT since I'm running 20 psi. I'm using a blow through MAF though so I haven't ever hit the limit on my stock MAF sensor. With a blow through MAF in front of the supercharger it's easy to max it out. Even easier if you have it in front of the turbo.

Seems weird to see the duty cycle going down like that because of the MAF being maxed, but it looks like that's what's happening. You can see it's definitely going way lean by the O2 readings too so things aren't happy.
 

bs009

Making 3800's Great Again
Feb 13, 2014
698
2,129
NashVegas
I was wondering about that for the longest time too. My GP is way faster than my brother's old ssei was, but his was maxing out the MAF under less boost and mine wasn't.

My idea I had until 5 minutes ago was that the MAF can't see pressure (apparently it can adjust for pressure? still learning more about that now), so it would just look at air velocity and if you increase the boost the air velocity wouldn't change, again looks like I'm wrong here.
I'll need to look into this though to see if pressure has some factor on its readings being lower.

It probably has more to do with the tight bend I have in front of my throttle body if that's the case. I still have the screen. I need to go look at my latest logs now I guess to verify...

So ignore everything I said about blow-through vs draw-through in my last post for now.
 

v6buicks

TCG Elite Member
TCG Premium
Oct 22, 2018
6,258
15,450
Franklin, IN
Real Name
Jon
I was wondering about that for the longest time too. My GP is way faster than my brother's old ssei was, but his was maxing out the MAF under less boost and mine wasn't.

My idea I had until 5 minutes ago was that the MAF can't see pressure (apparently it can adjust for pressure? still learning more about that now), so it would just look at air velocity and if you increase the boost the air velocity wouldn't change, again looks like I'm wrong here.
I'll need to look into this though to see if pressure has some factor on its readings being lower.

It probably has more to do with the tight bend I have in front of my throttle body if that's the case. I still have the screen. I need to go look at my latest logs now I guess to verify...

So ignore everything I said about blow-through vs draw-through in my last post for now.
I think I can help break this down a little bit. I only have an Auto Tech degree, but I worked in a fluid metrology lab for four years. The MAF measures mass flow. Hence grams per second. You are right in that a MAF cannot read pressure, but it does not need to. Regardless of pressure, flow is flow. The pressure of the charge does make the air more dense which makes the charge heavier and therefore more GRAMS per second.

In theory, you could meter air where ever you want because it has to move at the same rate everywhere. However, because of several factors there will be a slight delay the further the meter gets away from the throttle body. The variable of pre/post turbo comes to play depending on the performance of the MAF. From what I'm gathering, it seems that our MAF is much better at calculating a SLOWER (per seconds) but DENSER (grams) charge (blow through) than a faster less dense charge (draw through)
 

10sec

I haz dat teddy bear smile.
TCG Premium
Jul 26, 2008
25,942
5,810
If you want a direct result of not being able to meter the air anywhere you want, take the maf sceen out of your car and start it up. See just how badly the airflow goes past the hotwire on the maf without that screen in there to even it all out.

My guess for bs009 bs009 your bend right before the TB is forcing the air around the MAF so it isn't picking up all of the airflow.
 

bs009

Making 3800's Great Again
Feb 13, 2014
698
2,129
NashVegas
I think I can help break this down a little bit. I only have an Auto Tech degree, but I worked in a fluid metrology lab for four years. The MAF measures volumetric flow. Hence grams per second. You are right in that a MAF cannot read pressure, but it does not need to. Regardless of pressure, flow is flow. The pressure of the charge does make the air more dense which makes the charge heavier and therefore more GRAMS per second.

In theory, you could meter air where ever you want because it has to move at the same rate everywhere. However, because of several factors there will be a slight delay the further the meter gets away from the throttle body. The variable of pre/post turbo comes to play depending on the performance of the MAF. From what I'm gathering, it seems that our MAF is much better at calculating a SLOWER (per seconds) but DENSER (grams) charge (blow through) than a faster less dense charge (draw through)
This is helpful, but now I want to know how it can do that to see if there's a possibility of error in higher pressure situations. I need to consult with the internet more now :LOL:
 

b4black

before black
Jun 6, 2008
1,331
542
Oswego
The MAF measures volumetric flow. Hence grams per second.
Not volume - it measures mass. Mass Air Flow. Grams is mass. Volume would be cubic centimeters or liters etc.

Volume would be effected by air density. A given volume of air at twice the density will have twice the mass. The MAF will 'sense' this increased mass. A MAF compensates for different barometric pressures and altitude.

The pressure of the charge does make the air more dense which makes the charge heavier and therefore more GRAMS per second.
Correct (y)
 
  • Like
Reactions: Pewter-Camaro

v6buicks

TCG Elite Member
TCG Premium
Oct 22, 2018
6,258
15,450
Franklin, IN
Real Name
Jon
This is helpful, but now I want to know how it can do that to see if there's a possibility of error in higher pressure situations. I need to consult with the internet more now :LOL:
I don't recall the set up on your brother's SSEi. Is it supercharged? Turbo only? If its twin charged or supercharged then the speed across his MAF would be higher than yours (assuming you are running the same total boost pressure).
Not volume - it measures mass. Mass Air Flow. Grams is mass. Volume would be cubic centimeters or liters etc.

Volume would be effected by air density. A given volume of air at twice the density will have twice the mass. The MAF will 'sense' this increased mass. A MAF compensates for different barometric pressures and altitude.


Correct (y)
Yes, my mistake. Mass flow. Durr. I even spelled it out for myself and still said it wrong.

Original post edited for future readers.
 

bs009

Making 3800's Great Again
Feb 13, 2014
698
2,129
NashVegas
I don't recall the set up on your brother's SSEi. Is it supercharged? Turbo only? If its twin charged or supercharged then the speed across his MAF would be higher than yours (assuming you are running the same total boost pressure).

Yeah it's twincharged with an ST5 cam so it has tons of potential, it makes some of the coolest noises too but it's been just sitting for the longest time.
 
  • Like
Reactions: TurboTPI
I had this laying around, so might as well try and use it. Cheapo eBay core, 12x24x3. Should work better than nothin I guess.

8BF33F8E-0EE1-463E-8C34-5600DE958002.jpeg
 
Old Thread: Hello . There have been no replies in this thread for 90 days.
Content in this thread may no longer be relevant. Consider starting a new thread to get fresh replies.

Thread Info