[s-cars] RE: Math quiz: turbo compressor choices

[MLP]

One other thought occurs to me.  The author was "guestimating" AP in his
particular application of the formula at 14.5, not 14.7 psi.
Could that account for your 6.5% difference in cfm to lbs/min vs.. the
articles suggested 0.0756?
 
As for the 3.480086, how much boost were you running at 4,800 rpm?
Even so, a VE claim of 348% seems pretty high, ... and it gets higher if
you bump up the driveline loss adjustment (.83), i.e. 361% at 80% etc.

 
Mike   

-----Original Message-----
From: Djdawson2 at aol.com [mailto:Djdawson2 at aol.com] 

Mike,
Based on your info, I get:
VE=(792001.6*(325/.83)/(4800*135.8*14.7*9.3)

This doesn't make sense...  3.4ish....?

I based it on my dyno run, and input the rpm figure where that
horsepower figure was developed.  What am I doing wrong?  I used 14.7
for AP, as the dyno figures were corrected to sea level. I used 135.8
for the displacement (61.02*2.226).

Also, where did you get .0756 as your conversion figure for CFM to
lbs/min?  I generated mine by calculating the molar mass of breathing
air (28.9gm/mole), then converted liters to cubic feet... 1l = .0353147
cubic ft, so 1 mole (22.4 liters) of air = .791 cubic ft.  Therefore,
one cubic foot of air has a mass of 36.54 grams (28.9/.791).  Divide
that by 453.6 grams/lb, and I got .0806...  granted, only a 6.5%
difference, but I'm curious where your number came from, and if it is
more appropriate for these calculations..
Thanks for the info.
Dave