Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - View Single Post

scmil95eg · 05-22-2017, 03:13 PM

http://www.turbos.bwauto.com/afterma...6_wrsin=92044&

S&S: Pressure Ratio = Boost. 1:1 = atmospheric (no boost), 2:1 = 14.7 psi boost, 3:1 = 25.4 psi boost, 4:1 = 40.1 psi boost

Mass Airflow is just that - how much air the turbo can flow *by weight* at a given pressure
Why use mass or weight? Because in engines, different temperatures affect/change/manipulate volume. Weight is the only equalizer between air & fuel.
Every 13.07 cubic feet of std. atmospheric air weighs 1 pound.

RPM x CID x VE = CFM
CFM * 60 / 13.07 = lb/hr Air
lb/he Air / AFR = lb/hr Fuel
lb/hr Fuel / BSFC = FWHP

With a little more reading and a calculator, you should be able to put all the pieces together.

05-22-2017, 03:13 PM	#3
scmil95eg Member Join Date: Jul 2013 Drives: '95 delSol, '13 EvoX, '14 Leaf Location: miserable mitten Posts: 59 Thanks: 0 Thanked 48 Times in 26 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	http://www.turbos.bwauto.com/afterma...6_wrsin=92044& S&S: Pressure Ratio = Boost. 1:1 = atmospheric (no boost), 2:1 = 14.7 psi boost, 3:1 = 25.4 psi boost, 4:1 = 40.1 psi boost Mass Airflow is just that - how much air the turbo can flow by weight at a given pressure Why use mass or weight? Because in engines, different temperatures affect/change/manipulate volume. Weight is the only equalizer between air & fuel. Every 13.07 cubic feet of std. atmospheric air weighs 1 pound. RPM x CID x VE = CFM CFM * 60 / 13.07 = lb/hr Air lb/he Air / AFR = lb/hr Fuel lb/hr Fuel / BSFC = FWHP With a little more reading and a calculator, you should be able to put all the pieces together. Last edited by scmil95eg; 05-22-2017 at 03:28 PM.