This is actually trying to determine if 1992 was the last year for forged pistons, 5.0 engine, I have read and heard conflicting arguments. Some say 1990 was the last year., some 1993 except for the Cobras? I need an informative answer as I am not really up on the fox bodies.
According to Al Kirschenbaum's 1979-1993 V8 Mustang Specifications Guide, 1992 was the last year of forged pistons (part # E7ZA-6110-CA) and ALL 93 Mustangs (including street and R model Cobras) got hypereutectic pistons (part # F3ZE-6110-AA).
Pick up this months issue of MM&FF, the one with super charging your stang on the front...I forget what month it is. but there is a artical in there about a fox and it says in there that 92 was the last year for forged internals...
probably to stop all the whiners complaining of piston slap...the hypers can be fit tighter into the bore so no more slap, no more trips to the dealerships
probably to stop all the whiners complaining of piston slap...the hypers can be fit tighter into the bore so no more slap, no more trips to the dealerships
by the way, that was pure speculation on my part (at that being the reason why ford switched from forged to hypers) ...I'm sure it had something to do with $$$$$$$$$$$....it always does
wait they had forged internals? Why would they take them out?
It was for oil control. The rate of expansion of the hypereutectic piston is more similar to that of cast iron (than aluminum is). Therefore piston clearances vary less with temperature. Forged are still better for higher output (like boosted) engines.....
My car has more than 200,000 miles, and doesn't use a bit of oil, (and has had Mobil 1 since it hit 1000 miles.
Bob
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Bob S.
1993 Mustang Cobra #2296, Original owner, ex-daily driver @ 201,000 miles
1967 Corvette 327/350 Coupe
1966 Corvette 327/350 Roadster
1967 Porsche 911S Sunroof Coupe
2003 Honda S2000
1970 Porsche 914-6 Project in planning stage
ERA Cobra #470 (R.I.P. as of March '05)
I had to dig deep into my memory bank but thought it was done to lower emissions at start up - someone correct me if that's not the case. A quick search on google produced the following from Wikipedia:
It was discovered that when an engine was cold during start-up, a small amount of fuel became trapped between the piston rings. As the engine warmed up, the piston expanded and expelled this small amount of fuel which added to the amount of unburnt hydrocarbons in the exhaust.
By adding silicon to the piston's alloy, the piston expansion was dramatically reduced. This allowed engineers to specify a much tighter cold-fit between the piston and the cylinder liner. Silicon itself expands less than aluminium but it also acts as an insulator to prevent the aluminium from absorbing as much of the operational heat as it otherwise would. Another benefit of adding silicon is that the piston becomes harder and is less susceptible to scuffing which can occur when a soft aluminium piston is cold-revved in a relatively dry cylinder on start-up or during abnormally high operating temperatures.
The biggest drawback of adding silicon to pistons is that the piston becomes more brittle as the ratio of silicon is added. This makes the piston more susceptible to cracking if the engine experiences pre-ignition or detonation.
...I'm sure it had something to do with $$$$$$$$$$$....it always does 
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