The phrase "engine internals" refers to all the important parts inside an engine. These parts include pistons, valves, crankshaft, connecting rods, and other components that work together to produce power and make an engine run. Full definition
ARK Performance took a standard Hyundai Genesis Coupe and stroked its 3.8 - liter V - 6 to displace 4.0 liters, and then added stronger engine internals and a Rotrex supercharger. (automobilemag.com)
Beyond this you're into forged engine internals and saving weight. (evo.co.uk)
Thus, Subaru continues to ignore calls for a turbocharged BRZ, instead focusing on reworked engine internals (new pistons, rocker arm pivots, low - friction camshaft journals, etc.) along with better breathing from a new aluminum intake and freer - flowing exhaust manifold. (cnet.com)