quick view Choose Options SPEED PERF6RMANC3 SP63 Top Dog 2.5L Short Block | Mazda MZR-DISI MSRP: $4,800.00 SP63 Top Dog 2.5L Short Block The rod/stroke ratio affects several engine dynamics, including piston speed and acceleration, piston dwell at top dead center and bottom dead center, piston side loads, cylinder loading and bearing loads. Many of these... Choose Options Add to Wish List Add to My Wish List Create New Wish List