KeroPower, agreed - smallish OS LA in blue.

The other engine in later videos is identified in the clip showing the meter as it starts. Early 'credits' ID it as a Kyosho GX12 Nitro engine.

Things to remember with either glow or diesel engines: fuel, cooling, and exhaust 'gases.'

The fuel, as mentioned, cannot be simply filling station diesel for practical engines. Usually. it is a blend of kerosene, an igniter (ether), and oil. Consumption rates may limit the continuous run-time, if nothing else does.

Combustion engines operate by burning fuel to generate heat. Without airflow to cool exterior surfaces, better oil and/or more of it may help - as in RC car uses. The heat still must be considered.

Exhaust gases can consist largely of unburned oil, which has to be dealt with. Exhaust noise can also be a problem.