Compression Ratio - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

John_xr6 · 03-02-2004, 04:37

what is the formula for figuring this out? thanks in advance.

Aussiblue · 03-02-2004, 05:09

Compression Ratio = (Cylinder volume + chamber Volume)/(chamber volume)

Cylinder Volume = (pi/4) x bore squared x stroke.

or

Compression Ratio = (PV+DCV+HGV+CCV)/(DCV+HGV+CCV)

where PV=Piston Swept Volume
DCV = Deck Clearance Volume
HGV = Head Gasket Volme
CCV = Combustion Chamber Volume

John_xr6 · 03-02-2004, 05:17

i am assuming that piston swept volume is the dish in the piston? and is deck clearence measured when the piston is at TDC for the first half of the equation and and at BDC for the second half? or am i totally wrong.

Aussiblue · 03-02-2004, 05:25

Also see http://www.smokemup.com/auto_math/index.php and http://www.bgsoflex.com/auto.html and
http://www.thedirtforum.com/toolbox.htm

all these here http://www.martindalecenter.com/Calc...tml#AUTO-HORSE

Aussiblue · 03-02-2004, 05:29

a) Yes as swept volume is...
"that part of the cylinder capacity that is swept by the pistons on their up and down strokes (i.e., the volume through which a piston moves in one stroke) formed by the bore diameter and the piston stroke. Also called "displacement volume." See displacement. from http://www.100megsfree4.com/dictionary/index.htm

John_xr6 · 03-02-2004, 05:45

thanks for the info and the links AussieBlue, will get all my figures now and punch them in to see my compression ratio.