Forced Induction

Simulates turbocharger and supercharger systems that increase engine power by compressing intake air.

System Types

Turbocharger

Exhaust-driven with spool lag. Boost builds gradually with RPM and throttle, reaching maximum at high RPM.

Supercharger

Belt-driven with instant response. Boost increases linearly with RPM, no spool lag.

Configuration

Use Forced Induction

Enables or disables the forced induction system. When disabled, engine operates naturally aspirated using base power curve only.

Forced Induction Type

  • Turbocharger: Exhaust-driven with spool lag and wastegate behavior
  • Supercharger: Mechanically-driven with instant RPM-based boost

Power Gain Multiplier

Power multiplier at full boost (range 1.0-3.0). Actual multiplier interpolates from 1.0 (no boost) to this value based on current boost level.

Typical values:

  • 1.2-1.3: Mild boost (20-30% gain)
  • 1.3-1.5: Moderate boost (30-50% gain)
  • 1.5-1.8: High boost (50-80% gain)
  • 1.8-2.5: Extreme boost (80-150% gain)

Spool Up Time

Turbocharger only. Time in seconds to spool from zero to full boost at high RPM with full throttle. Forced to 0 for superchargers.

  • 0.2-0.4s: Small turbo (quick spool)
  • 0.4-0.8s: Medium turbo (balanced)
  • 0.8-1.5s: Large turbo (noticeable lag)
  • 1.5-3.0s: Very large turbo (extreme lag)

Has Wastegate

Turbocharger only. Simulates wastegate valve that dumps boost pressure when throttle closes at high boost (boost > 0.7). Triggers onWastegateRelease event for flutter/blow-off sounds.

Boost Calculation

Turbocharger:

  • Target boost = rpmPercent * 2.0 * throttlePosition
  • Smoothed to target using spoolUpTime
  • Drops to 0 during gear shifts
  • Wastegate dumps boost instantly when throttle closes at high boost

Supercharger:

  • Boost = rpmPercent * 2.0 (clamped 0-1)
  • Instant response, no smoothing
  • Direct RPM correlation

The boost value (0-1 range) drives the power multiplier and can be used for gauges/UI.

Sound Integration

Use onWastegateRelease event to trigger turbo flutter/blow-off sounds. Event parameter contains boost value at release for volume/pitch adjustment.

Example Setups

Street Turbo Sport Car

  • Type: Turbocharger
  • Power Gain Multiplier: 1.5
  • Spool Up Time: 1.0s
  • Has Wastegate: true

Supercharged Muscle Car

  • Type: Supercharger
  • Power Gain Multiplier: 1.4
  • (Spool time ignored)

Big Turbo Track Car

  • Type: Turbocharger
  • Power Gain Multiplier: 1.9
  • Spool Up Time: 2.2s
  • Has Wastegate: true

Troubleshooting

No boost: Verify Use Forced Induction enabled, Power Gain Multiplier > 1.0, throttle applied, sufficient RPM

No lag on turbo: Increase Spool Up Time, verify type is Turbocharger not Supercharger

Too laggy: Decrease Spool Up Time

Insufficient power: Increase Power Gain Multiplier, ensure base engine power curve is adequate