It is my belief that the 1993-1995 Magnum 5.9 V8 pistons had 11 cc 'soapdishes'
Willem Weertman's memoir on his time as the chief engineer at Chrysler engines
http://www.allpar.com/reviews/other/engines.htmlsays that these same hyper-eutectic aluminum cast pistons were used in the 1994-1995 iron V10 Ram pickup engines as well.
But somewhere in the 1996-1998 time frame I think the 5.9L V8 piston soapdish was enlarged to 13 to 14 cc
When this change was made Chrysler started calling the official compression ratio 8.9
whereas the early FSM manuals list the 5.9L as 9.1 just like the 5.2L engine.
As others have posted above
the deck height clearance
varies a lot
and will determine what real world static compression ratio will be for any given engine.
There seems to be a hint
that the deck clearance runs tighter on the rear most cylinders.
Larry Shepard wrote that the
Magnum combustion chamber was 'about 60 cc'
but most of the reports of actual measurements by owners are 62 cc to 65 cc.
Once again, there seems to be a trend that the factory machining leaves the rearmost chambers of the cylinder head slightly smaller.
We know that the early 1992-1993 5.2L engines had a larger exhaust manifold and exhaust pipe back to the catalytic converter,
then in 1994 this was surprisingly made smaller and more restrictive.
The only plausible answer I have read for this change was that the exhaust gas temperature was "too cool" for the catalytic converter to reduce the NOx pollution,
and so Chrysler had to find a way to raise the exhaust gas temperature, even if it meant worse horsepower and fuel economy.
Lower static compression ratio also raises exhaust gas temperature,
so it is possible that Chrysler fiddled with the compression ratio in a year that they were having problems pass the EPA test for NOx,
or maybe the CARB test instead.
