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YUP, that is only ONE way to cast a piston, there are more ways, all better than dead pour casting, as seen in that video.
There are two methods of dead pour, drop media (as in the video), and vacuum suction, where the media is vacuum drawn into the mold from the bottom. Of these, there are two mold types, sand casting, and then, permanent mold.
There is injection molding, where the molten aluminum is pressured at low pressure, through the permanent mold, good method.
Then, pressure die casting, where the metal is injected into the mold at high pressure, better method.
Best method is centrifugal spin casting. This method injects the media into a permanent mold that is spinning, to help evenly distribute the media through the entire casting.
The main issues with casting anything (aluminum, steel, whatever), are air pockets/voids in the media produced, and, even distribution of the media during the casting process. The dead casting methods ware ancient, were the first methods used, and still work well, IF the mold is good, and IF modern media with updated metallurgy is used.
I got lambasted by a "top tuner" on the old board, for mentioning that my friend from New Zealand, Burt Munro, used to come here for Bonneville, and used the dead cast/full pour method in his pal's back yard, casting pistons for his Bonneville racer Indian, in the DIRT, and, from that person's all out attacks on me, that I advocated a dead cast dirt cast piston for our motorcycles above a Wiseco forged piston. NOT SO, but, I do advocate a significantly better centrifugal spin cast piston for our bikes, for every application over what BillB uses, drag racing. A good quality cast piston uses significantly less cylinder to skirt clearance, helps with ring seal, and just plain works better than large clearances forged pistons require. New tech cast pistons of today are leaps and bounds better than early type dead castings were, and no longer so far off what a forged piston is in strength.
We stopped having piston flex, skirt collapse, and clearance and ring issues when the factory switched in early 1973, from a forged piston, to a centrifugal spin cast one for our H2R's. We could set up a set of factory forged H2R pistons at the required .0045 clearance, then, run the engine for 10 laps, and pull the barrels off, to find skirt clearances of .012 to .014, with NO wear on the cylinder bores, just skirt collapse below the wrist pin center line. The factory cast racer pistons would collapse only .001 in a full race meet. We also stopped having ring problems with the cast pistons, and we ran them at .002 clearances.
I have been in that casting room at Egge, as the home I moved out of to move here, was 3 streets up from Slauson Avenue, and Egge. I used to go there every day to help out with older car parts. Egge is at the corner of Slauson Avenue, and Dice Road, Santa Fe Springs, Ca. Dice Road T's into Slauson Avenue, at Egge, miss the turn onto Slauson from Dice, and you will end up IN Egge's showroom.
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