This Smithsonian activity set lets you build a real working battery powered, four-cylinder model engine. The learning accessory features real lights and sounds as it lets you see how the pistons fire with the correct timing. Build a real working battery powered 4-cylinder model engine with real lights and sound. Watch the spark plugs fire and the valves open and close. See how the pistons fire and watch the belts and fan turn. Detailed instructions are included.