Fuel delivery must match your power goal with control at idle and cruise. The right injectors flow enough for peak power while remaining precise at small pulse widths. Size with headroom. Aim for injectors that run well below their maximum duty cycle at target power. Consider fuel type. Ethanol blends need more flow for the same power. Check compatibility with the fuel you plan to use.

Character matters as much as size. Good injectors have tight flow matching and consistent latency. That gives smooth idle, clean cold starts, and even cylinder-to-cylinder fuelling. The ECU’s deadtime table should match the injectors so fuelling is accurate across voltage changes. For staged setups, blend secondary injectors in gradually, maintaining stable lambda through the transition.

Fitment is practical. Use proper rails, seals, and adapters. Keep the loom away from heat. Add a fuel pressure sensor and reference it to manifold pressure so the ECU can correct for variations. Closed-loop fuel control trims small discrepancies, but the base tune should not lean on corrections to stay safe.

On the dyno, look for stable lambda at tip-in, steady values at full load, and clean cut on over-run. Good injectors help the ECU achieve all three. The result is a car that starts well, cruises cleanly, and makes the power you built it for.