Complex sentence: The 340 is thought by many Chrysler diehards as having the best bore to stroke ratio out of all LA engines produced by Chrysler, hence why all "R" (R1-R3 race blocks) blocks are derived from the 340 dimensions.
Split into simpler sentences: The 340 is thought by many Chrysler diehards as having the best bore to stroke ratio out of all LA engines produced by Chrysler. Which is why all "R" (R1-R3 race blocks) blocks are derived from the 340 dimensions.