Piston and Pulse

Piston & Pulse is a pocket museum of the internal combustion engine — and a workshop where you get to build one yourself.

Five landmark engines, spanning 1876 to today, are drawn as living engineering blueprints. Every part moves the way the real mechanism moves, because the motion is calculated from the actual geometry rather than looped from a video. Open the throttle and watch the machine respond.

THE ENGINE HALL

Step through the timeline and see what each generation changed:

• 1876 — The four-stroke gas engine. One enormous cylinder, a flame for ignition, and a flywheel heavy enough to carry the machine between power strokes.
• 1897 — Compression ignition. No spark at all: squeeze air hard enough and the injected fuel lights itself.
• 1963 — The rotary. A triangular rotor orbits an eccentric shaft inside a peritrochoid housing, its apex seals tracing the chamber wall. No valves, no pistons.
• 1989 — Variable valve timing and lift. One camshaft with two personalities, switching to the high-lift profile at 5,800 rpm — watch the indicator light up as you cross it.
• Today — The hybrid power split. An Atkinson-cycle engine married to two motor-generators through a planetary gearset. Toggle between engine power, electric drive and regenerative braking to see the energy change direction.

Each exhibit is labelled like a real drawing: leader lines naming the parts, a full specification sheet, and a short curator's note on why the engine mattered.

THE DYNO CELL

Design an engine from scratch. Set the bore, stroke, cylinder count, compression ratio and boost pressure, choose your fuel, and make a pull.

The horsepower and torque curves are computed, not canned — thermal efficiency from the compression ratio, volumetric efficiency shaped by your bore-to-stroke choice, friction rising with mean piston speed. Build it oversquare and it revs; build it long-stroke and it makes its torque low down and runs out of breath up top.

Push the compression or the boost too far for your fuel and you will hear about it. Detonation ends the pull at peak cylinder pressure, the curve stops dead, and the engine is scrap. Higher-octane fuel buys you more compression; E85 buys you a lot more. Chase your best peak horsepower.

THE MILESTONE BENCH

Five challenges, each built around the genuine engineering compromise its era faced:

• Balance flywheel inertia against a slow-burning flame — too light and the engine shakes itself apart, too heavy and windage eats the power.
• Find the highest compression 19th-century castings will survive before the cylinder lets go.
• Trade apex seal preload against friction: enough to survive redline, not a gram more.
• Place the cam crossover exactly where the two lift curves meet, so there is no torque hole at the switch.
• Balance Atkinson-cycle efficiency against battery state of charge, and finish the cycle without running flat.

Every challenge has a real sweet spot to find, and real ways to fail.

BUILT ON REAL NUMBERS

The physics is simplified for a phone, but it is not decorative. Displacement, compression ratio, thermal efficiency and the knock threshold follow standard engine relationships, and the trade-offs behave the way they do on a real dyno.

WHO IT IS FOR

Anyone curious about how engines actually work — students, mechanics, car and motorcycle enthusiasts, and museum visitors who want to see the mechanism move, not a static display. No engineering background required: the exhibits explain themselves, and the challenges teach the trade-offs by letting you break things.

PRACTICAL

• The exhibits and simulators run on your device — no account, no sign-up, nothing to create.
• Designed for phones, with a dark, low-glare blueprint interface.
• Supported by advertising.

Piston & Pulse is an independent educational project. All trademarks referenced are the property of their respective owners; this app is not affiliated with, endorsed by or sponsored by any vehicle or engine manufacturer.