Attention! Forged Mahle Pistons

[Sydneykid]

There is no magic in pistons, no secret formulas that disobey the laws of metallurgy. If W brand piston has X alloy mix it then it will expand at EXACTLY the same rate as Z brand piston with the same alloy mix. It doesn’t matter where it is made or who made it.

As usual with all things mechanical it is simply a compromise, in this case piston strength versus expansion rate. That is purely a factor of its metallurgy. So if you have a W brand piston that expands less than a Z brand piston, then the W brand piston is not as strong.

More silicone makes the alloy brittle and less tolerant of detonation. OE cast pistons are typically 12% or so silicone content. More silicone means the piston has a lower rate of thermal expansion. Forged pistons are typically less than 1% silicone (2618 alloy for example), hence their higher inherent strength. But this means they expand more, so have to run higher clearances when cold.

There are a number of different alloys used by piston manufacturers, but the fact is a 2618 alloy forged piston made by Tomei will expands EXACTLY the same as a 2618 alloy forged piston made by Mahle. So don’t look to the manufacturer for some form of magic, there isn’t any, look at what alloy they use and the clearances they recommend.

cheers

[Muz]

There is no magic in pistons, no secret formulas that disobey the laws of metallurgy. If W brand piston has X alloy mix it then it will expand at EXACTLY the same rate as Z brand piston with the same alloy mix. It doesn’t matter where it is made or who made it.

As usual with all things mechanical it is simply a compromise, in this case piston strength versus expansion rate. That is purely a factor of its metallurgy. So if you have a W brand piston that expands less than a Z brand piston, then the W brand piston is not as strong.

More silicone makes the alloy brittle and less tolerant of detonation. OE cast pistons are typically 12% or so silicone content. More silicone means the piston has a lower rate of thermal expansion. Forged pistons are typically less than 1% silicone (2618 alloy for example), hence their higher inherent strength. But this means they expand more, so have to run higher clearances when cold.

There are a number of different alloys used by piston manufacturers, but the fact is a 2618 alloy forged piston made by Tomei will expands EXACTLY the same as a 2618 alloy forged piston made by Mahle. So don’t look to the manufacturer for some form of magic, there isn’t any, look at what alloy they use and the clearances they recommend.

cheers

Thanks (again) SK. Fact will always win out over emotion.

[Mik]

There is no magic in pistons, no secret formulas that disobey the laws of metallurgy. If W brand piston has X alloy mix it then it will expand at EXACTLY the same rate as Z brand piston with the same alloy mix. It doesn’t matter where it is made or who made it.

As usual with all things mechanical it is simply a compromise, in this case piston strength versus expansion rate. That is purely a factor of its metallurgy. So if you have a W brand piston that expands less than a Z brand piston, then the W brand piston is not as strong.

More silicone makes the alloy brittle and less tolerant of detonation. OE cast pistons are typically 12% or so silicone content. More silicone means the piston has a lower rate of thermal expansion. Forged pistons are typically less than 1% silicone (2618 alloy for example), hence their higher inherent strength. But this means they expand more, so have to run higher clearances when cold.

There are a number of different alloys used by piston manufacturers, but the fact is a 2618 alloy forged piston made by Tomei will expands EXACTLY the same as a 2618 alloy forged piston made by Mahle. So don’t look to the manufacturer for some form of magic, there isn’t any, look at what alloy they use and the clearances they recommend.

cheers

Exaclty...but the shape of the piston, pin offset and skirt length also makes a difference...