Powertrain

The Powertrain page configures your vehicle's power generation, transmission, and drivetrain systems. The powertrain is modular — subsystems are conditionally shown or hidden based on your power source type and optional feature toggles.

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Component Structure

The powertrain is a parent component that references up to six child components. Each child is an independent library item that can be saved, loaded, and shared separately.

graph TD
    PT["<b>Powertrain</b><br/><i>Power Source Type + Drivetrain Type</i>"]

    ENG["<b>Engine</b><br/><i>Torque curve, RPM limits</i>"]
    MOT["<b>Electric Motor</b><br/><i>Torque curve, RPM limits</i>"]
    BAT["<b>Battery</b><br/><i>Cell config, voltage maps</i>"]
    GRS["<b>Gears</b><br/><i>Ratios, shift strategy</i>"]
    EFF["<b>Efficiency</b><br/><i>Constant or 2D map</i>"]
    DIF["<b>Differential</b><br/><i>Type, locking behaviour</i>"]

    PT --> ENG
    PT --> MOT
    PT --> BAT
    PT --> GRS
    PT --> EFF
    PT --> DIF

    style PT fill:#6366f1,color:#fff
    style ENG fill:#ef4444,color:#fff
    style MOT fill:#10b981,color:#fff
    style BAT fill:#10b981,color:#fff
    style GRS fill:#f59e0b,color:#fff
    style EFF fill:#8b5cf6,color:#fff
    style DIF fill:#8b5cf6,color:#fff

Not all components are active at the same time — which ones are available depends on your configuration:

Component	ICE	EV (FWD/RWD)	EV (Hub Motors)
Engine	Yes	-	-
Electric Motor	-	Yes	Yes
Battery	-	Yes	Yes
Gears	Yes	Yes	Yes
Efficiency	Optional	Optional	Optional
Differential	Optional	Optional	Optional

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Page Layout

The Powertrain page is arranged in three rows:

Row 1 — Top: Three columns

1. Configuration — Power source type, drivetrain type
2. Engine (ICE) or Electric Motor (EV) — Power plant settings
3. Hub Motor Settings — Only active when drivetrain is Hub Motors

Row 2 — Middle: Three columns

1. Battery (EV only) — Cell configuration and voltage maps
2. Efficiency (optional) — Engine/motor efficiency modelling
3. Differential (optional) — Torque distribution behaviour

Row 3 — Bottom: Full width

• Gears — Ratios, shift timing, shift strategy, and visualisations

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Configuration

The Configuration fieldset contains the two primary selectors that determine the overall powertrain architecture.

Power Source Type

Option	Description
Internal Combustion Engine (ICE)	Shows the Engine component. Hides Electric Motor and Battery.
Electric Vehicle (EV)	Shows the Electric Motor and Battery components. Hides Engine.

Switching power source type automatically creates the required child components if they don't already exist.

ICE and Hub Motors

If you switch from EV to ICE while the drivetrain is set to Hub Motors, the drivetrain is automatically changed to Rear Wheel Drive (RWD), since Hub Motors require an electric power source.

Drivetrain Type

Option	Description	Availability
Front Wheel Drive (FWD)	All drive torque goes to the front axle	ICE and EV
Rear Wheel Drive (RWD)	All drive torque goes to the rear axle	ICE and EV
AWD Hub Motors (HM)	Individual motors at each wheel with configurable torque bias	EV only

Hub Motors and EV

Selecting Hub Motors automatically switches the power source type to EV if it isn't already.

Hub Motor Settings

When the drivetrain is set to AWD Hub Motors, the Hub Motor Settings fieldset becomes active:

Parameter	Description	Unit
Torque Bias	Distribution between front and rear hub motors. 0 = all rear, 1 = all front, 0.5 = equal.	decimal (0–1)
Max Power	Maximum power limit per axle (front and rear independently). This is the total axle limit — for vehicles with 2 motors per axle, the limit is shared across both.	kW

The Max Power field is optional. If not set, power is limited only by the motor torque curve.

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Optional Components

Efficiency

The Efficiency component models drivetrain losses between the power source and the wheels. It is toggled on/off with a switch in the section header.

• When disabled, all drivetrain efficiency is assumed to be 100% (no losses)
• When enabled, the Efficiency component becomes available for configuration

See Efficiency for full details.

Differential

The Differential component models torque distribution behaviour between the driven wheels. It is toggled on/off with a switch in the section header.

• When disabled, an open differential is assumed
• When enabled, the Differential component becomes available for configuration

See Differential for full details.

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How Torque is Calculated

The powertrain processes torque through a chain of components:

Power Source (Engine/Motor)
    → Base Torque at RPM
    → × Efficiency (if enabled)
    → × Gear Ratio × Final Drive × Bevel Ratio
    → Wheel Torque
    → ÷ Rolling Radius
    → Drive Force
    → Split by Drivetrain Type (FWD/RWD/HM)

Force Distribution

Drivetrain	Front	Rear
FWD	100%	0%
RWD	0%	100%
Hub Motors	Torque Bias	1 − Torque Bias

Total Efficiency

The total efficiency applied to the base torque is the product of all efficiency stages:

Total Efficiency = Motor/Engine Efficiency × Gear Efficiency × Final Drive Efficiency × Bevel Efficiency

Each of these is configurable in the Gears and Efficiency components.

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Validation Warnings

The powertrain validates the overall system configuration. Subsystem-specific warnings are documented on each component's page.

EV Source Warnings

Condition	Warning
Motor max voltage > 95% of battery nominal voltage	Limited voltage headroom
Motor max voltage < 70% of battery nominal voltage	Possible efficiency loss
Power-to-energy ratio > 50	Rapid battery depletion risk
Power-to-energy ratio < 5	Oversized battery

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Subsystem Pages

• Engine — ICE torque curve, RPM limits, engine braking
• Electric Motor — Motor torque curve (1D or 2D), RPM limits, max power
• Battery — Cell configuration, voltage/discharge maps, internal resistance
• Gears — Gear ratios, shift timing, shift strategy, inertias
• Differential — Differential type, FACES inputs, locking behaviour
• Efficiency — Constant or RPM/torque-dependent efficiency