A car engine built from synthesis, for games. Give it RPM, throttle, gear and speed, the values a racing game already has, and it plays an engine: each cylinder's exhaust pulse runs through headers, a collector, a muffler and a tailpipe modelled as real pipes, with intake roar, valvetrain and gearbox, tyres and wind, pops when you lift, a turbo or a supercharger, and the car heard from behind, from the engine bay, from the driver's seat or from the side of the track as it passes.
Play it
Drive is the default. Hold W / ↑ for throttle and S / ↓ for brake; press or drag either physical pedal or its adjacent meter, then release to let it spring back. Driving shortcuts continue working after clicking a mode or gear button. Text fields and musical sliders keep their normal keyboard edits. The first pedal press or driving key starts host audio automatically; Demo is not required. Startup failures appear beside Demo, and another press retries.
Choose the gearbox explicitly:
- Automatic owns all gear changes. The gear keys are read-only, and number keys or Q/E cannot silently switch it into Manual.
- Manual accepts 1–6 for a gear, 0 / N for neutral and Q/E / ← → for adjacent gears. Clicking the numbered keys or Shift uses that same car model and engagement sound. A request during a shift waits for its clutch cycle; it does not repeatedly restart the shift.
The top-right Demo switch runs varied acceleration, braking and sound changes through the automatic gearbox. It never slips into Manual between stages. An explicit mode/parameter/pedal edit takes over. Auto lap retains its separate repeatable driving sequence. Game follows external RPM, throttle, gear and speed directly through the existing host parameter inputs.
Releasing throttle changes engine pressure and brightness while the engine continues firing at its current RPM; it does not release a volume envelope. Free revs fall quickly to idle. In gear, compression braking slows the road speed and crank. Downshifting may briefly exceed redline at the corresponding higher pitch; a continuous torque governor pulls overspeed down instead of hard-clamping RPM or repeatedly muting the ignition.
The ivory RPM instrument has a damped physical needle and an immediate numeric reading. Its damping changes only the drawing. The eight-second control profile shows actual RPM, requested/received throttle, brake, shifts/clutch and output peak, with time and range markings. The mechanical controls share connected radio groups; the former colorful piston schematic is no longer part of the face.
Default sound
Garage turbo is the startup sound and first factory preset: four cylinders, V cross-plane, Turbo, Drive with Automatic gears, heard from the exhaust in a garage. Its long, wide exhaust matches the selected screenshot: 0.66 m headers, 2.94 m mid-pipe, 0.90 m chamber, 1.50 m tailpipe and 90 mm bore. The other named factory sounds keep their existing settings.
Shape the engine
- Cylinders and Layout: inline, cross-plane V (the V8 burble, or a 90° V-twin with two cylinders), flat-plane V (a supercar scream) or boxer (the unequal-header rumble).
- Induction: natural, turbo (lag, whistle, blow-off valve) or supercharger (whine).
- Roughness: uneven firing and cylinder-to-cylinder variation.
- Exhaust: build the pipe. Headers, mid-pipe, muffler length and tailpipe set where the resonances fall; the bore sets how bright it radiates; Muffler goes from a straight pipe to a quiet stock system. The diagram draws the pipe to scale.
- Redline: where the automatic gearbox approaches its shift point and overspeed governing begins.
- Crackle: how often unburnt fuel pops in the exhaust off throttle.
- Cold start: the starter cranks and the engine catches to a fast, lumpy idle.
Listen from
- Listener: Exhaust (behind the car), Engine bay, Cabin or Pass-by (trackside, with Doppler and the ground reflection).
- Space: open air, a city street, a concrete garage or a tunnel, with echoes off the walls and a reverberant tail; Space amount sets how much.
- Distance: quieter and darker further away.
- Exhaust, Intake, Mechanical, Road and wind: the balance of the sources.
In a game
The parameters a game sends are car.rpm, car.throttle, car.gear and car.speed, with drive.mode set to Game. The engine view shows them as the calls a game would make. See development notes for how it works and what it is based on.
Instrument panel
The instrument is bounded at 1180 pixels so its three-column layout keeps a consistent control scale in wider hosts. Smaller hosts use the same responsive sections.
The top dashboard groups driving modes and pedals on the left, the ivory RPM dial in the center, and aligned gear/speed readouts with load/boost on the right. Connected radio segments make each exclusive choice one visible control. Below are three control columns: Engine, Exhaust in the center, and Listener. A bottom row groups audition controls, live control history and Mix output. Click the speed readout to switch km/h / mph; game inputs and saved speed parameters always remain in km/h. The illuminated brake/throttle ribs show what the engine receives, and a white marker shows your request. Pointer and keyboard pedals remain spring-loaded.
Demo starts a varied audition through the ordinary Drive model: randomized acceleration, braking, gear changes and small roughness/crackle/muffler/pipe changes. Each run has a fresh sequence. Manual editing or driving takes over; stopping Demo releases both pedals. Auto lap still plays the repeatable lap. Choose from the existing factory presets in the header before starting a demo.
The exhaust drawing is editable: drag a section vertically, use its arrow-key controls (Shift for fine adjustment), Home/End for bounds, or double-click to reset. The normal knobs edit those same parameters. The colorful piston schematic is removed; the Listener section keeps its two acoustic controls together in one row. RPM has the dominant ivory dial, with compact digital speed and gear readouts alongside. Shift and Backfire use inset, tactile event buttons with visible E and B keycaps. E (or Right arrow) shifts up in Manual/Game mode; B triggers Backfire. Text entry, key repeat, power state and Automatic gear ownership are respected.
Selected references · Implementation and verification.
The preserved original mockup and visual comparison record the reference materials and current control artwork. Knobs continue to use UI-kit gestures, parameter taper, host automation and hover/edit captions.
Website catalog
Engine Synth is included in the public web catalog through its canonical maru.catalog declaration. The Games listing and /modules/engine-synth demo consume the same packaged module; the manifest is no longer local-only. The next normal site release includes it. This does not add native-format availability or publish a site release by itself.
The website preservation inventory protects the custom dashboard, shared parameter controls, interactive exhaust and grouped radio selectors. Public release artifacts and browser qualification are generated by the existing website module packager; the local workbench remains the fast editing preview.
