I own a wide array of model engines. Typically those engines are either glow engines using nitro fuel, spark engines using gasoline or "diesel" engines using "kerosene". However I recently acquired a 6cc engine that runs using a glow plug (like a nitro engine), but it is fueled with gasoline.

I was curious, what are the mechanics that allow an engine to work on gasoline without a spark plug? Is it higher compression? Is it a special plug with a different catalyst that helps ignite the fuel/air mixture? Is it something completely different?

1 Answer 1


The glow plug engines have a glow plug that gets heated from a power supply and once it is hot, the repeated combustion process is sufficient to keep it hot so that it can ignite the fresh incoming charge.

This can happen with gasoline engines that have suffered a build-up of carbon deposits and is often called "dieseling" or self-ignition, when the carbon stays ignited through the exhaust and intake part of the engine cycle.

  • That was my understanding of glow plug engines as well. But this engine I bought is specifically designed to run on gasoline fuel and it works perfectly fine. You preheat the glow plug, run it quite rich and it will start and run without any spark plug. Dec 14, 2021 at 20:48
  • However if I take my run off the mill nitro engine and feed it with gasoline it wont start at all. So apparently the gasoline engine I have with the glow plug has something different compared to the nitro version of it. My question was, what is that thing that is different? Dec 14, 2021 at 20:48
  • @YanickSalzmann That is what I said in my answer... But you may find the jets are different for nitro compared to gas...
    – Solar Mike
    Dec 14, 2021 at 20:49
  • But the gasoline engine does not have any carbon build up, it is pristine metal, both the piston/cylinder and the glow plug. Is the coil of the glow plug a different material from the nitro engine? In a way I might be able to rephrase my question to: "What do I need to do to turn my normal nitro glow engine into a gasoline glow engine?" Dec 14, 2021 at 20:51
  • Why don't you check to see if there are different glow plugs for the different fuels? I would think to check that, as fuels have different combustion temperatures etc
    – Solar Mike
    Dec 14, 2021 at 21:00

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