Engines you can actually run.

A cutaway drawing shows you where the parts are. It cannot show you why a two-valve pushrod V8 makes its torque low down, or what happens when the fuel is too low-octane for the compression ratio. You cannot draw a behaviour; you have to run it. So drag the compression slider here and the torque curve, the exhaust note and the detonation all move at once, because there is nothing underneath them but the model.

How it works

Geometry first

Bore, stroke, rod length, compression, bank angle, firing order. Change one and everything downstream of it moves.

A cycle at a time

Wiebe heat release against real crank angle, through a lumped gas path: plenum, runners, collector, tailpipe.

240 times a second

A fixed physics step, independent of frame rate, so an engine behaves the same on a school laptop as on a gaming desktop.

The sound is the engine

Every firing event makes its own pulse, and the rate they repeat at is the pitch you hear. Nothing here is a recording.

The writeups go through the model piece by piece, and the changelog records every physics change as it ships.

What is in it

29

piston

2

radial

4

rotary

3

turbojet

Some are built to a named real engine’s published bore, stroke and compression ratio, and the roster says which figures agree; the rest are honest builds of a layout and claim nothing more. You can also design one from scratch.

What it is not

• Not a dyno sheet. We solve the numbers; nobody measured them. They land close where somebody checked the model against a real engine, and nobody has checked the rest.
• Not finished. Exhaust temperature and fuel consumption are both wrong in specific ways we have written down. When we fix them, published figures will move.
• Not affiliated. A real engine name says which engine we modelled. No manufacturer is involved, and we use no logos or trade dress.

Who makes it

February Solutions, MB, registered in Lithuania (company code 308104153). Readers choose much of the roster. Every engine request arriving through the feedback form gets counted by distinct submitter, and the ones people keep asking for get made. When we cannot model something truthfully we say so instead of shipping it. A Harley’s shared-crankpin firing interval is the current example, and it is why you will not find a V-twin here.

Adverts and the occasional coffee pay for the site. Nothing sits behind a paywall, and we sell no personal data. The privacy policy sets out what we collect and how to switch the optional parts off. Found something wrong with the physics? That is the most welcome email we get, so get in touch.