MAF Upgrad

bruce plecan nacelp at bright.net
Tue Feb 24 18:20:51 GMT 1998


Some points to ponder, other than my hat (HOHOHAHA)
OK, let's just for grins pick some numbers  (again GM Style)
(normally aspirated)  Stock MAF say flows 250 gms/sec
            lets say it a frequency type and at 20 gms/sec (idle)
            is 20 Hz, and at 250 gms/sec, 250 Hz (WOT)
We now take 2 and tie them together, and add the 
  frequencies together then we have a workable system
  til the total of the frequencies hit the original 250 Hz
  cause the computer has an upper limit on the freq..
  So we might/will flow more air, but have no additional
  fuel metering control, or spark adjustment,  beyond the
  the original 250 Hz. (Only corrective action I know of
  is running rich enough, here to cover later, and some
  combination of that for timing, here there thinking)
Next we take 2 MAFs, but only read one.  All of sudden
  we can read more but how much more, what is the
  WOT freuqency goin to be?.  Maybe 10%, maybe 50%
  Your going to have to cut the resolution of the tables
  (spark, and WOT fuel enrichment) unless you flow 2x
  as much air.
Next item 400HP, is alot of ponies.  At this level ya 
  gonna need to do some serious breathing, ie.
  short runners, large plenum, and all of a sudden
  reversion raises it head.    Remember on a MAF
  system it reads air flow, and it don't care which 
  way it's moving.  So any reversion present at the
  MAF gets read twice,  so while it corrects at
  part throttle for fuel  (the ecm is using the O2), 
  you'll still be reading off the spark table at gms/sec/rpm,
  including the reversion  ugh, might not be good!!
  (neat thing about turbos F.B., they act as check
   valves, for reversion, since they're always spinning)
So while the stock MAF might make 4 HP more than
  MAP, at 350 HP and I'm using TPIS's numbers for this
  when you go off the stock MAF scale youre going
  to spend alot of time tuning.
All of a sudden Peter's discovery of a TPS/RPM
 Scale looks pretty good, with maybe some 
 combination of the above.  Or jus one of them
 dumb/slug MAPs.  
  BETCHA, I missed something?.
Bruce   Tis wiser to be, retarded and rich
            rather than, smart and poor.
 Yes, Grasshopper we be talking tune-ups



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