It looks like a turbine because I see no cheater holes or cylinder heads poking out through the nacelles, although those could be in a hidden location. I do not know if model turbines would create a noticeable heat disturbance given that plane's design, bypass ratios common for such designs, and the environmental conditions (background clouds).
There are a few giveaways, but I don't want to list them because maybe other people don't know what I saw that let me know it was "subscale" and it's fun to let them guess
