n2otoofast4u Posted October 15, 2015 Report Share Posted October 15, 2015 Certainly not always. Quote Link to comment Share on other sites More sharing options...
blowit Posted October 15, 2015 Report Share Posted October 15, 2015 That's always been my understanding based on my readings. Perhaps not always the case? Not really accurate to say "forged is lighter than casted". About the only way to make any assumptions is to compare the densities of the different alloys used for both forgings and castings. As mentioned, you typically will use a hypereutectic high silica alloy for castings which is a trade off between elasticity and surface hardness or wear resistance. Believe me, a lot goes into that alloy blend to ensure a good compromise. Based on the structural characteristics of each alloy and the intended structural design, you then add or subtract material to meet the requirement. As commonly done in aerospace, we closely look at the structural need and remove extra material that is not needed to reduce weight. Even within forgings, you will see some pistons much heavier than others. Lighter is NOT always better. Lighter means you are taking away material that you might actually need. However, in a piston requirement, inertia is a bitch.... ie, that piston has to accelerate and decelerate a LOT and that can wear on the wrist pin locations as well as rods/bearings. There are tradeoffs in both cast and forged. The reason forged pistons need more room is they thermally expand all funny due to the natural grain being stretched in funny directions. Grain is sort of like rubber bands. With an annealed alloy, the rubber bands are all relaxed but as we add heat treatments or semi-solid forming (forging), you are stretching the rubber bands which improves structural performance. So no, you cannot blanketly say forged is lighter because it is heavily determined by the features and dimensions of the part. Then I guess you get into the elasticity of the pistons. there is a small amount of deformation of the piston during use. This deformation gets nasty with bad conditions such as pre ignition and detonation. Forged pistons handle these stresses better due to their alloy composition and elastic properties. Thus why you typically see race engines with forged pistons. Cast will last longer thus their extensive use in OEM engine applications. 1 Quote Link to comment Share on other sites More sharing options...
Big Mike NY Posted October 15, 2015 Report Share Posted October 15, 2015 Forged cast ceramic coated Pistons FTW! Bingo, I run them in my turbo Camaro!!!! Diamond Pistons ceramic top coat! Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted October 15, 2015 Report Share Posted October 15, 2015 Forged cast ceramic coated Pistons FTW!Guy across the street is convinced his son's CR250 has a Carbon Fiber piston in it..... Quote Link to comment Share on other sites More sharing options...
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