OBD-II and P-Flow Results! (Long but interesting!)

["Mark Radelow" <rpcprod@hotmail.com>]

Alrighty here is the final word on the P-Flow vs. Stock Modded Box 
decision.  At the past meeting of the VW Club of Los Angeles we hook up 
a laptop running the OBD-II program into a 1997 GLX with modded airbox 
and K&N (mine) and another members 1996 GLX with a P-Flow.  The results?  
Amazing.  The OBD program can measure airflow (measures in grams per 
second) as well as intake air temperature (in degrees C).  Although I do 
not have the EXACT figures with me (you'll have to wait to see them on 
my page along with the data files) the results were pretty cool.

Modded Stock Airbox with K&N airfilter

Air Intake Temp (Freeway)
approx.  32-34 degrees C

Air Intake Temp (City Streets)
approx.  40-45 degrees C

Max Velocity Air Intake
143 grams per second

P-Flow

Air Intake Temp (Freeway)
approx.  34-36 degrees C

Air Intake Temp (City Streets)
approx.  60(!) degrees C

Max Velocity Air Intake
143 grams per second

**City Streets was a five mile course through stop and go as well as 
some empty neighborhood streets.  Yes, we drove the cars pretty hard.

**Why grams per second?  Most likely because the air mass sensor needs 
to take into account higher and lower elevations.  I cubic cm. of air 
down here is not the same as it is in Denver


These numbers are not EXACT, but are quite close.  In a few days the 
actual data files (In Excel format I believe) will be uploaded.  So what 
does this all mean?  Unless you like the P-Flow's sound, forget it.  
This has been said before, but this ALSO shows the P-Flow does not even 
flow more air!  Yes maybe the velocity of air increases faster so you 
get better throttle response; but the loss of power definately makes it 
not worth it.  A difference of 20 degrees C is 68 degrees F.  That's the 
difference between driving in 50 degree whether and 118 degree weather!  
Oh, the stock eight valve (w/P-Flow) flows ~64 gms/sec. max.  

Is the program accurate?  Even if we account for a 10% error (which is a 
HUGE amount) differences are still huge.  In the next few weeks I will 
do a proper statistical sample and will get some more exact numbers.

Anyways, if you have any questions regarding the test, email me.  If you 
live in Los Angeles or surrounding parts come to a VWCOLA meeting and 
see the test for yourself!


Mark Klaus Radelow
VW Jetta Homepage
http://jetta.aosi.net
VW Club of Los Angeles
vw-club-of-los-angeles@rocketmail.com

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