Ross Forged Pistons

[gaz097]

From what I've found they run a bout a thou less in bore to wall clearance so yeah would be quieter.

[jimmixr]

Yep..atomics are a cosworth forging. They run about 2.5 thou..

[gaz097]

That's ridiculous. What does a naturally aspirated cosworth piston require?

[FORCEDG6E]

I just hope my machinest knows what hes doing about all this becuase im lost

[jimmixr]

No Idea what n/a tolerances are. But I do know a lot of LS1 applications actually run a interference fit of 1thou !!!

That's why its imperative that a torque is used when machining. I had one made at great expense..

[gaz097]

I just hope my machinest knows what hes doing about all this becuase im lost

They just machine to a nominal bore diameter so its pretty hard to mess up.The bore to wall clearance is built into the piston itself. Looking at my paper work Ross recommend a 5 thou clearance. That's why they rattle.

[jimmixr]

They would rattle with those clearances..

[Peppy_t92]

Manley recommend 0.003" measured 1.1" down from the bottom of the oil ring

[jimmixr]

Yeah because of the shape of the piston.Actually wider in the middle section

[straughsberry]

Clearance depends on the type of alloy used. 4032 expands less so you can run tighter clearances. 2618 expands more so needs more clearance but generally are said to handle more. I see that the Ross units are made from 2618.