MAF flowrate - velocity - someone check my calcs

[PhilW]

Wouldnt you have to compare it to the ibiza id maf? So 64 vs 79mmID?

So would work out at theoretical 320g/s so 420+?

Unless it was scaled up to 69mm id which would make. 297g/s so 392?

Have i worked that out?

Whatever it is thats shifting some serious air! What turbo is it alex?

 

[DPJ]

Im not really too hot on this subject. My car pulled 260g/s at 1.8 bar last night. The maf im using is an rs4 79mm id unit, thats not been scaled yet from the lcr 69mm id one i used to have. What would that make my true g/s?

Cheers, Alex

341 g/s, Alex. (Assuming the LCR one was scaled to read correctly).

 

[Backdraft]

I believe the old map/current map is scaled for the 69mm unit. How exactly is it worked out?

The turbo is the 2871r 86 back housing. Its on my car with the ported head, SEM etc.

 

[DPJ]

(Cross sectional area of Larger MAF) / (Cross sectional area of smaller MAF) x airflow

(79/2 x 79/2 x pi) / (69/2 x 69/2 x pi) x 260 g/s

 

[Wilko]

Alex
are you sure you don't have an s4 maf
they measure 78-79mm at the end, but read aprox 20%
higher than the tt/s3 maf.
This would make 260g/s -->312g/s which is roughly 41lb/min, which is around the compressor max flow of the 2871

 

[DPJ]

Alex
are you sure you don't have an s4 maf
they measure 78-79mm at the end, but read aprox 20%
higher than the tt/s3 maf.
This would make 260g/s -->312g/s which is roughly 41lb/min, which is around the compressor max flow of the 2871

John, I can take it if you just come out and say "You're wrong, Dave" ...........

 

[ibizacupra]

I believe the old map/current map is scaled for the 69mm unit. How exactly is it worked out?

The turbo is the 2871r 86 back housing. Its on my car with the ported head, SEM etc.

the 2ltr one max log of 286g/s on 2871/0.86
nothing left in the turbo's flow capacity

 

[Wilko]

John, I can take it if you just come out and say "You're wrong, Dave" ...........

Not at all dave. Your calc would work, but I think you need to take the area of the sensor itself into account. I only know that an S4 is 1.21 x the area of an S3 maf from back to back testing from peak flow on the same turbo.

 

[Backdraft]

Alex
are you sure you don't have an s4 maf
they measure 78-79mm at the end, but read aprox 20%
higher than the tt/s3 maf.
This would make 260g/s -->312g/s which is roughly 41lb/min, which is around the compressor max flow of the 2871

Yes it is an s4 maf. My mistake. Im going to do some more logs tomorrow and i will post them up. Revo are sorting me a linear throttle map out for next week like the ktm's. Its really nice on them.

 

[Wilko]

With 257g/s through the same maf with Revo code, I saw 38x hp at awsome (363whp)
New Owens unit it maxing the S4 maf Reading 297g/s (350 in reality) from 6k onward.