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Crankshaft

The rotating backbone. Its inertia governs throttle response and idle stability, and its strength is one of the RPM ceilings.

What it is

The crankshaft converts the pistons' up-and-down motion into rotation. For tuning, its key properties are rotational inertia (how much it resists changes in speed) and its bearing specs.

Why it matters

Crank inertia is a balancing act:

  • High inertia (a heavy crank) makes the engine stable at idle and smooths out power delivery, but it makes the engine slow to rev — lazy throttle response.
  • Low inertia (a light crank) gives snappy throttle response but a less stable idle that's more prone to hunting and stalling.

Every part has a hidden RPM ceiling, and the weakest one decides where the engine breaks. Engone doesn't print it — you find the limit by pushing, so don't set your rev limiter past what you've tested. A weak crank can cap the whole engine, and over-revving damages it (see Damage & Wear).

How to tune it

Match crank inertia to the engine's purpose. A street engine values the stable idle and smooth delivery of more inertia; a race engine wants the response of a lighter crank and accepts a busier idle (which idle control then has to manage).

Rule of thumb

Lighter crank = faster revs but twitchier idle. If a light build hunts at idle, that's the trade-off you bought — tune idle control to suit, or add inertia.

In the game

Crank selection is the CRANKSHAFT dropdown on the SETUP page. Its inertia contributes to Total Inertia in the specification summary, and visibly affects how fast RPM rises on a throttle blip and how steady the idle sits.