340 Piston to valve clearance w/RHS heads

The speed pro pistons are almost exactly the same weight as the original CAST pistons....yes, they were cast. There's no reason why the piston material will cause it to smoke...more like the rings being warn. Lubricants were different then. Ever seen what the stock shortblock will take on an 88-92 5.0 Mustang? Those have forged pistons from the factory.

I saw that both the KB & Speed Pro pistons are either made in Mexico or India depending on what their application is. The interesting thing about that is I'm MUCH more likely to trust a forging made in a 3rd world country than a casting. Grain structure is way better on any forging...and its easy to have porosity problems on a casting.

I have absolutely NO interest in the hypereutectic pistons...plain and simple..even old topics on this site where people were having problems with wearing out/burning rings. I'm not worried about saving the very small amount of money...especially when this deal will probably be 4-5 grand by the time its done. Forged pistons do not explode, they do not crack down the center, and the ring lands don't break off at anywhere near the rate of hypereutectic pistons if ever. If someone could quantify the power gain from using lighter pistons (have never seen/cant find such a test...they probably haven't done it because its less of a difference than you think OR they know you should use forged at any high power level where you would care), then I would call Diamond up and get a nice custom lightweight forged set made....btw Diamond's 0.030 over forged piston is 566g....that is a shorter compression height but still, adding 0.020" will add maybe 40-60g.

My junk cast crank 77 360 that's a .040 over rebuilder special and has a zillion miles on it and FM cast pistons hasn't blown up either. Detonation & running too lean (don't ask), way too hot (230 degrees for 45 minutes the night before the dream cruise), not much oil pressure, overrev in gear before I had a limiter (6700rpm)...the ductility may have helped in these cases. These things are tough anyway, but I spent the extra money to get a 340 so I could have forged everything....so I'm going with my wishes.

My friend has an all forged 468 big block chevy with iron LS6 heads, stock crank, rods, and some heavy dome pistons and it turns 7400rpm....and was built in the 80s...goes 10.0's. Doesn't break either. Street car....and doesn't smoke.

For a lot of people...better=cheap...I'm not willing to do so on this build. Take a metallurgy class and then tell me if you still like cast hypereutectic pistons. The difference in process alone is kind of eye opening. Pretty hard to screw up a forging as long as they did a decent job machining.