Burning natural gas in a direct injection diesel engine, requires a special arrangement to secure ignition. In this study a hot surface assisted ignition concept is investigated in a constant volume combustion bomb and a test engine with the objective to develop a better understanding of the mechanisms involved. The experiments show that surface temperature above 1200 K is required to achieve acceptable ignition, strongly dependant on natural gas composition and system parameters such as injection and hot surface geometry. A mathematical model of the concept is also being developed. Numerical simulations combined with experiments allow us to look closer into the processes, and to expand the test matrix even outside the physical limits of the test engine. This paper will give an outline of the investigation including some results from experiments and numerical simulations. Furthermore some design features concerning interactions between the gas injection parameters and the hot surface will be discussed.