Turbocharging & Boost Control

Boost smart. Make pressure work for you.

From wastegates to solenoids, here’s how to set up and understand turbocharging systems — and how our BoostIT controller makes control precise and repeatable.

1) Anatomy of a turbo system

  • Turbocharger: compresses intake air, powered by exhaust gas.
  • Wastegate: controls exhaust flow to turbine (internal or external).
  • Intercooler: cools compressed air for density & knock safety.
  • Boost control solenoid: modulates pressure to wastegate actuator.
  • MAP sensor: measures boost level for ECU/controller feedback.
Key idea: Boost is just airflow resistance. The real metric is air mass + charge temperature that reaches the cylinders.

2) Boost control basics

  • Duty cycle (%): How long the solenoid is open. Higher duty = more boost (to a point).
  • Gain: How aggressively the controller reacts to boost error.
  • Boost cut: Safety limiter — shuts throttle/fuel/spark if boost exceeds threshold.

    • On the MX-5 NC, stock bottom end is comfortable ~0.6–0.7 bar with good fueling. Forged setups handle 1.0+ bar depending on turbo and cooling.

    3) BoostIT Controller — Quick Setup

    • Wire solenoid to BoostIT output (IO23 default).
    • Set base duty (e.g., 35–45%) for spring pressure.
    • Adjust gain until boost rise is clean without oscillation.
    • Set boost cut just above target (e.g., target 1.0 bar → cut 1.1 bar).
    Tip: Log boost curves after each change. BoostIT stores the last pull graph so you can compare trends.

    4) Common issues & fixes

    Boost creep

    • Wastegate too small or flow path restrictive.
    • Fix: larger gate, better manifold design, less preload.

    Oscillation / hunting

    • Gain too high → reduce step by step.
    • Vacuum/boost leak or incorrect solenoid plumbing.

    Early boost cut

    • Cut threshold too low in ECU/controller.
    • Sensor scaling mismatch (MAP reading high).

    5) Safe boost levels (MX-5 NC)

    Stock bottom end

    • 2.0L NC: ~0.6–0.7 bar (safe zone with correct tune)
    • 2.5L NC: ~0.5–0.6 bar (higher torque load)
    • Fuel quality & IAT management are critical

    Forged builds

    • 1.0–1.3 bar depending on turbo, cams, and fuel
    • Requires larger injectors (1000cc+ for E85)
    • Clutch & diff upgrades strongly recommended

    Always tune with wideband + knock monitoring. Boost without control is just an engine lottery ticket.

    6) FAQ

    Can I run a manual boost controller?

    Yes, but you lose flexibility and safety features. Electronic control (BoostIT/ECU) is more stable and loggable.

    Do I need a bigger MAP sensor?

    Stock NC MAP sensor reads up to ~1.5 bar absolute (0.5 bar boost). For higher boost, upgrade to 3 bar MAP and rescale in tune.

    Does exhaust size affect boost?

    Yes — restrictive exhaust raises backpressure, spools earlier but limits top-end. Our 3” turbo systems are designed for flow and serviceability.

    Need help dialing in boost? We’ll guide your BoostIT setup or ECU duty maps for stable, safe power.
    Ask Yiannis