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 elements play roles in engine aspiration, combustion and wear. Generally, a lower ratio means a high rod angle, creating greater potential for accelerated wear to cylinder walls, pistons and rings. A low enough ratio, due to the severity of its rod angle, can drive a piston right into the cylinder wall. Higher ratio engines, on the other hand, don't have the same friction concerns, but compromise in other areas.