In this study ignition of premixed ammonia was tested using a compression-ignited (CI) pilot fuel. n-heptane (C7H16) used as fuel, injected with GDI injector, enabling very small fuel injections. With setup, the engine run up to 98.5 % energy from – higher than seen in other CI-engine studies at time writing. The contribution varied 80–98.5 %, while keeping total λ-value constant. An important ...