13:1 Compression Pistons in 340 Small Block

If you do plan on running the pistons as is, you could have some of the weight machines out of them in the pin bosses and underneath the domes for about half the cost of a new set of lightweight pistons. Unless you have a T/A 340 or R block that has extra webbing for four bolt mains, I wouldn’t go nearly that all out. A 10.5:1 4.07 inch bore small block with a well prepared econo W-2 is capable of exceeding the typical power rating (550 hp) of an x block.