Originally posted by ERL2004
I might be wrong, but from what I know. In the past some of the pistons were machined from aluminum bars . Nowdays they are casted, giving the advantages of lightness and complicated intrisic design possible. I am not sure whether you can use powder metal technique because I think they can only use one type of metal and it is not the type of aluminum alloy we use in RC engine, it looks more like steel or iron.
The biggest problem with casting high silicon content alloy is getting porosities in the casting. Si particles don't disperse uniformly in alluminum. To control the particle size it has to be heated to a certain temp, let it cool down at a specific rate.
But it is all aluminum manufactured secrects.
A newer technique is spray forming process which give you high density Si-Al. It can incorperate upto about 50% Si. but the piston will cost more than an engine you can get now.
This is the one of the reasons ( secret of casting) we will never realiese and ( as I noticed-you are pretty familiar with airmodeling) you will know what Russian piston material is.
About poweder Al alloy with 35 % Si, I can supply you by tons, with realy good dispersed Si in alloy, but it is not going to work as material we use on our engines and P/S sets.