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Old 04-04-2013, 02:29 PM   #235 (permalink)
ausias
Burning oil to move air.
 
Join Date: Aug 2011
Location: Valencia (Europe)
Posts: 126

ausiasmobil - '06 Seat Leon 1.9 TDI Reference
90 day: 40.22 mpg (US)

EcoTxec - '99 Skoda Octavia 1.9 TDI 110 cv Laurin & Klement
90 day: 52.85 mpg (US)
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Quote:
Originally Posted by MetroMPG View Post
Roll your own: a few years ago we had a member who was working on a method of converting data logged from the OBD-II interface into a BSFC map. I had a look ... but couldn't find the thread I'm remembering.
I tried several times and with the data logged from OBDII it is not possible (always get constant factors conversions i.e mg/stroke to torque). you need accurate accelaeration data, drag, rolling resitance, wind, a flat road or accurate slope, etc. or some engine direct torque measuring or Roller dynamometer bank like a MAHA, etc.
and C02 accurate emissions will be a best way than OBDII data (Carbone are alway from fuel, 140 g of C02 means 4.5 L of diesel burned).
enigenes does'nt measure injection quantity, we pressume that for guetting 3.6 mg/stroke we apply 1.35 V to the injectors or pum, etc. OBDII data really talks about voltages being applied or measured (MAF, etc.)

Air metering is right if you dont change your air intake,i.e.

You obtain l/h in obdii data from fuel consumption (liters/hour) = rpm x IQ x conversion factor.

I think from Air Flow or Air mass you can get data (scangauge does it?) about meaasured Volumetric Efficiency (assuming nothing changed in air intake).
You always need a way of measuring real work and real fuel consumption to obatain BSFC map, i think.
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