Ξ€here is a growing interest in smaller displacement engines, i.e 20 or 25 cc (or even smaller), equivalent to 1.20 to 1.50 glows . Most 1.80 to -say- 2.10 m wingspan warbirds need a 1.20 to 1.50 glow engine.
The problem with a glow engine, bigger than .90, is that it is ''nitro-thirsty''. For a fly-day you may need 2 liters or more of expensive fuel. A 1-gallon container (3.7 liters) costs here, in Greece, 31 bucks-and that's the best price you can find.
There comes the need for low displacement 4-cycle petrol engines. 4-cycle, because it is a ''sacrilege'' to hear from your beautiful warbird this unbearable howling, that the 2-stroke engines launch to your face.
Undfortunately, it seems that there are not such engines, apart of course these from SAITO, which -for many of us- are not affordable.
The question is why the Chinese have not produced yet 4-cycles engines.