3" MAF/MAFT Combo Questions...

[QuickerDSM]

"Boost Threshold",,,, that's what tripped me up on my last post.

I think I got it now.

Mike

 

[HighPSI TSi Guy]

you all make this way too complicated.. and uh.. wrong.. by one mode of reasoning one of you stated my car will always flow the same @ the same PSI no matter what turbo.. uhh.. yeah.. anyone who thinks that belongs in hte n00b forum not the tuning forum... otherwise screw the 50 trim i want my 14b back yo cuz it flows the same, and it spools quicker too!

the ramchargers unit is great in that it allows the use og a GM MAF, creating potential for more flow. what is not great about it is it's tuning abilities.. calculationg load based on airflow is not accurate at all as different cars/setups can flow the same amount of air with different ammounts of load. this is the point i am making. this thing makes does what we all hate the stock boost guage for.. throttle and MAP are closer to real load than raw airflow readings.

this unit is great.. with an AFC

 

[nine5raptor]

Originally posted by HighPSI TSi Guy
you all make this way too complicated.. and uh.. wrong.. by one mode of reasoning one of you stated my car will always flow the same @ the same PSI no matter what turbo.. uhh.. yeah.. anyone who thinks that belongs in hte n00b forum not the tuning forum... otherwise screw the 50 trim i want my 14b back yo cuz it flows the same, and it spools quicker too!

I said neglecting the larger exhaust housing effect. don't believe me? check out the extreme tuner forum (not the noob forum
http://www.dsmtuners.com/forums/showthread.php?s=&threadid=22470

 

[99GSTRaptor]

HighPSI,

When you talk about airflow, you are talking about volumetric airflow, or CFMs. The translator deals with Mass airflow, or g/s, lb/min.

CFMs can be very different at different points in your system, but lb/min will be the same. You can't take away or add mass to the air. I think this is what nine5raptor is trying to get at. The reason the MAF translator works is because the Mass airflow/revolution of the engine is a good assumption for boost.

Many people get confused because so many turbos are rated in CFM. This is the WRONG way to rate them. Go to any well respected vendor or engineer and they will always give you a Mass airflow, such as 54lb/min.

Eric

 

[HighPSI TSi Guy]

Originally posted by 99GSTRaptor
HighPSI,

When you talk about airflow, you are talking about volumetric airflow, or CFMs. The translator deals with Mass airflow, or g/s, lb/min.

CFMs can be very different at different points in your system, but lb/min will be the same. You can't take away or add mass to the air. I think this is what nine5raptor is trying to get at. The reason the MAF translator works is because the Mass airflow/revolution of the engine is a good assumption for boost.

Many people get confused because so many turbos are rated in CFM. This is the WRONG way to rate them. Go to any well respected vendor or engineer and they will always give you a Mass airflow, such as 54lb/min.

Eric

CFM and lb/min are different ways of measuring the same thing.. most mitsu turbos are rated in CFM and most garrets are rated in lb/min as well as the hybrids... it's like inches and meters..

do you still use your factory boost guage?

 

[99GSTRaptor]

HighPSI,

CFM and lb/min are meant to both measure airflow, but they are not the same thing. I just didn't feel like writing a book here to explain something that can be found in many books about turbocharger theory and thermodynamics.

lb/min is MASS airflow. CFM takes into account pressure and temperature and volume, hence the cubic feet per minute. For example, the air flow coming into the turbo, out of the turbo, into the intercooler, out of the intercooler, into the intake mani, out of the intake mani, all have the same mass air flow, but the CFM is very different at those points due to the different temperatures, pressures, and volumes.

Again, I don't feel like writing ten pages of text and formulas to explain everything. I am just making a point that the MAF translator is based on MASS airflow/revolution and that is a good estimation of boost.

And as far as the stock boost gauge, no I don't use it. I don't have the algorithm in front of me how it works, but I know it uses some sort of airflow/engine revolution. I'm not saying that the MAF translator is perfect for measuring boost...MAP would be ideal. But, it is a good estimation, that's all I am saying. That is why there are knobs to tune with, so that you can adjust for errors in the calcualtion. Although, personally, I don't care that much as I use DSMLink for tuning, I will just be using the MAF translator to open up the restriction in the airflow path for my 2G.

 

[HighPSI TSi Guy]

Originally posted by 99GSTRaptor
And as far as the stock boost gauge, no I don't use it. I don't have the algorithm in front of me how it works, but I know it uses some sort of airflow/engine revolution. I'm not saying that the MAF translator is perfect for measuring boost...MAP would be ideal. But, it is a good estimation, that's all I am saying. That is why there are knobs to tune with, so that you can adjust for errors in the calcualtion. Although, personally, I don't care that much as I use DSMLink for tuning, I will just be using the MAF translator to open up the restriction in the airflow path for my 2G.

my point. only the adjustment ability sucks.