How Engines Work. Visible V-8 Engine kit is ideal for budding mechanics and modelers. They''ll build an engine that''s 1/4 actual size. When they turn the crank, the parts move-perfectly timed like a real V-8! Crankshaft rotates, valves open and close, rods and pistons move up and down-all seen through the transparent engine block! No painting required. Parents'' Choice Award. Ages 10+.