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Question for turbo experts

959 views 3 replies 3 participants last post by  John_G 
#1 ·
Probably pretty simple and dumb, but how do you convert lb/min to cfm on a compressor flow map? I've found several different math formulas, but I can't seem to get any of them to work right. I have a swing of anywhere from 13 lb/min to 168 lb/min. Can somebody help me?
 
#3 ·
Thanks, that is way more simple than the equations I was getting before. Know of a good place to get maps? They're hard to find on the internet and most are only for smaller turbos.
 
#4 ·
Strokerin said:
Probably pretty simple and dumb, but how do you convert lb/min to cfm on a compressor flow map? I've found several different math formulas, but I can't seem to get any of them to work right. I have a swing of anywhere from 13 lb/min to 168 lb/min. Can somebody help me?
Well it is certainly not a dumb question, and it is definately not simple either.

The real answer is that it completely depends on the temperature and barometric pressure.

However, in general, the density of "air" at sea level is very close to 1.28kg/m^3.

There are 2.2 lbs/kg, so 1.28 x 2.2 = 2.82 lbs/m^3, and

1 m^3 = 35.31 ft^3 ( for 2.82lbs. of air)

So, (35.31ft^3/m^3) / (2.82 lbs/m^3) = 12.52 ft^3/lb or 0.079lb/ft^3

Therefore, 1 CFM = approximately 0.079 lb./min. (Or pretty close).


Doing this another way,

1.28kg/m^3 = 2.82lbs/m^3,

1m^3 = 35.31 ft^3/m^3,

So (2.82lbs/m^3) / 35.31ft^3/m^3 = 0.0798lbs/ft^3

Therefore, 1 CFM = Apx. 0.079 lb./min.
 
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