Im new here, first question, converting flow numbers

Discussion on general flowbench design
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MJCustom
Posts: 2
Joined: Sun Oct 21, 2012 5:05 pm

Im new here, first question, converting flow numbers

Post by MJCustom »

Hi, im in the process of building a fixed depression flow bench.
Im waiting on my metering plates to be cnc machined so currently its just floating depression.

i have a head that has been flow tested on a digital super flow.
iv done some extra porting to the exhaust and recorded the before and after results on the vertical nanometer.

its very promising. my question is for eg if at 12mm lift the gauge used to read 16.45 inches and now after porting reads 12.44 inches can i assume that it flows 32.2% more? (16.45/12.44=1.322)

thanks in advance.

Jason
86rocco
Posts: 292
Joined: Thu Mar 04, 2010 9:01 pm

Re: Im new here, first question, converting flow numbers

Post by 86rocco »

Unfortunately, that's not quite the way the math works, the relationship between flow and pressure drop is NOT linear rather, it's a squared relationship, Flow squared is proportional to pressure drop so the the correct calculation would be √(16.44/12.45)= 1.15 or 15%.
MJCustom
Posts: 2
Joined: Sun Oct 21, 2012 5:05 pm

Re: Im new here, first question, converting flow numbers

Post by MJCustom »

Oh thanks for that.

15% still sounds good to me. The nanometer showed the same pressure drop at 7mm lift as the old port at 12mm lift so
Hopefully that equates to good things!
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