Drivetrain¶
Flywheel, clutch, and gearbox between the engine and the load. Inertia here trades response against stability; ratios multiply torque.
What it is¶
The drivetrain connects the engine's output to whatever it's driving. Its components:
- Flywheel — adds rotational inertia at the crank.
- Clutch — its capacity (how much torque it can hold) and engagement behavior.
- Gearbox — the ratios and their reflected inertia.
- Dyno drum — the load used for measurement (see Dyno).
Why it matters¶
- Flywheel inertia is the same trade as the crankshaft: a heavy flywheel smooths idle and launches and resists stalling, but blunts throttle response and slows revs; a light flywheel is snappy but busier at idle.
- Clutch capacity must exceed the engine's torque or it slips under power.
- Gear ratios multiply torque to the wheels (or drum) and set how engine RPM maps to road/drum speed. Lower (numerically higher) gears multiply torque more but cover less speed. Reflected inertia means a tall gear makes the engine feel heavier to accelerate.
How to tune it¶
Match the flywheel to the engine's purpose (smooth street vs responsive race), size the clutch to hold peak torque with margin, and choose ratios for the balance of acceleration and top speed you want.
Rule of thumb
A light flywheel revs fast but, like a light crank, makes idle twitchier. Size the clutch above peak torque — a slipping clutch wastes everything the engine makes.
In the game¶
Drivetrain parts are on the Setup page; their effects show in throttle response, idle stability, and how the engine pulls against the dyno drum.