I'm really struggling pls help

Basically ive just got flyout and made a jet , it flies well and has decent firepower. Now I'm trying to make a prop plane but I can't seem to get the engine to produce any power I've got it set as radial and 2 rows with 7 pistons on each I have the gear shift thingy and the prop I've messed with the setting but have pretty much no idea what I'm doing

Pls help . Edit 1 : Ok quick updt I've got it to fly barely but when I go 100 % throttle the engine power drops significantly so I keep it at 75 - 94 %

Thanks for all the tips this has helped so much :)