Small Engine Start

How it's made

Source

a small four-stroke engine; an electric starter turns against compression at 3 cycles/s. Gear-mesh harmonics at 350-1100 Hz dip under each compression load, with filtered brush friction.

Body

compression and exhaust excite damped 65-180 Hz pressure modes; the casing adds broad 380-950 Hz coloration, while short 1.4-3.2 kHz valve ticks follow the crankshaft.

Envelope

engagement attacks in 2 ms; cranking lasts 0.65-1.35 s. Two weak combustion strokes catch, then firing accelerates for 0.25 s, overshoots idle by 45%, and settles over the next 0.5 s.

Layers

each combustion stroke has a 2 ms pressure attack, 45-90 ms damped body, and a softer 55-80 ms turbulent exhaust burst. Intake turbulence and crankshaft vibration fill the idle gaps.

Variation

seeded timing jitter, stroke strength and tuning model imperfect combustion. Crank time, idle speed, engine size, roughness and muffler damping define warm, cold, scooter and enclosed presets.

Space

dry, centered close perspective. A 180 ms editorial fade ends the idle excerpt, not a shutdown; all excitation is band-limited, sub-30 Hz energy removed, with 100 ms of silent tail inside 3.1 s.

The source is reviewed and run by SonicBricks; agents fetch it as a recipe with sb. It is not published on this page.