There seems to be little info on the manufacturing process involved in forging pistons for the om617, namely the turbo model.

There's a cavity in the crown for an oil duct, but what I want to know is how in the name of Rudolf this is possible... I could see how it could be done with a casting, but how is this accomplished through a forged piston? Beats me...

Also, if any members have some pistons that are unusable anymore, consider donating one to me so I could cut it open for the sake of curiosity and boredom... If I do I'll make a thread, seems somewhat interesting.

The pistons are cast.

From what little I know of high-end pistons for gas engines, one step up is "hyper-eutectic alloy" aluminum casting. There are forged aluminum pistons, but I don't know if that process is the same as forging steel, i.e. beating it into a mold w/ a hammer. While stronger, a disadvantage of forged aluminum pistons is that they expand more with temperature, so must be looser in the bore when cold and thus give more "piston slap" sound. They are thus better for race cars than daily drivers.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Conventional forging with aluminum is not very popular. But there are all kinds of casting technology out there to produce premium aluminum parts, such as:

- permanent mold casting
- die casting
- low pressure casting
- high pressure casting
- squeeze casting (slushy metal)

Sometimes the cavity is flushed with argon before casting to help eliminate porosity.

I've seen technology where they join two forgings to make a lightweight piston.

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95 E320 Cabriolet, 169K