How an engine works
A drawing that moves: pistons, valves and the timing chain work right in front of you. Change the layout, the number of cylinders or the dimensions and the engine rebuilds at once.
Inline, V, W and boxer
Four layouts and anywhere from one to sixteen cylinders. Open any of them and take it apart.
Inline
All cylinders in one row. Most cars use it: inline fours, threes and straight sixes.
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V
Two banks at an angle on one crankshaft. That is how V6s and V8s are built: shorter than an inline engine with as many cylinders.
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W (VR)
Two banks at a narrow angle under one cylinder head. A compact Volkswagen design: the VR6, and two of them make a W12.
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Boxer
The banks lie flat, facing each other, and opposite pistons move as mirror images. Subaru and the Porsche 911 use it.
Open in the emulatorWhat the drawing shows
Every part is built from the engine’s dimensions, so the drawing changes along with them.
123456- 1
The four strokes
Intake, compression, power and exhaust. You see where each piston is and what happens in its cylinder at any moment.
- 2
Valves and camshafts
The cam lobe pushes the valve open and the spring closes it. You see when each valve opens and how far.
- 3
Timing chain
The crankshaft drives the camshafts through the chain at half its own speed. Tensioners and guides keep the chain tight.
- 4
Cam phasers
They turn the camshaft relative to the crankshaft, so the valves open earlier or later.
- 5
Firing order
Which cylinder fires next. On this V8 it is 1-8-4-3-6-5-7-2.
- 6
The charge
Gas in the cylinders and pipes: where the fresh mixture is and where the exhaust goes.
One engine, three views
From the front you see the pistons move and the chain at work. From the top, how the cylinders sit along the crankshaft. From the side, the cylinder head, camshafts and manifolds. All three views move together.
Questions and answers
What is this?
A free piston engine emulator that runs in your browser. It draws the engine in three projections and shows how it works: the strokes, the valves, the timing chain and the firing order.
Do I need to install anything or sign up?
No. Open the page and start. You can save your engines; they stay in your browser.
Which engines can I build?
Inline, V, W and boxer engines with one to sixteen cylinders. Valve drive: overhead camshafts with two or four valves, or pushrods. There is a timing chain, cam phasers, balance shafts and an accessory belt.
Does it work on a phone?
Yes. Phones, tablets and computers each get their own layout, and you switch projections with arrows.
Where do the power and torque numbers come from?
They are an estimate from the engine’s dimensions, not a dyno measurement. They show how bore, stroke and compression ratio change the output.
Is there sound? Is it a game?
There is no sound and it is not a game. It is a drawing that moves, made for seeing how an engine is built.
How do I share my engine?
Under Saved builds there is a Share button. Anyone who opens the link sees your engine; no account needed.