Re: Comp Ratio and Pressure Ratio

["Brant M. Miller" <brant@xxxxxxxxxxxxxx>]

Neil -

A reason that compression testing yields a higher pressure than atmospher=
ic
times the compression ratio is the compression heating of the gas.  When =
a
gas (normally air when performing a compression test, but sometimes with
some fuel mixed in) is compressed, its temperature increases. =

Somebody-or-other's law says that P2=3DP1(V1/V2)(T2/T1).  Your calculatio=
n
took into consideration only the V1/V2 part of the equation.

Cheers

Brant

>Date: Tue, 11 Aug 1998 22:17:29 -0400 (EDT)
From: Neil Deshpande <deshpand@domain.elided>
Subject: M3 Compression Ratio.  Velocity pressure to static?

If the highest measured pressure at a cylinder is 13.75 bar, and the
intake pressure is atmospheric or 1 bar (actually, I remember that about
1.012 bar is 760 mm Mercury or 1 atm), should not the compression ratio b=
e
about 13.75:1?  . . . . =

Neil Deshpande
86 325
<

------------------------------