Why are horsepower claims useless? Are they lying? Do you actually have to mount a certain engine onto a certain airplane to decide for yourself whether it is a good engine or not? I'm not being mad or angry or anything, I'm just shopping for an engine and want to know the best way to get the most for my money. I see some engines that have high horsepower ratings and they are really heavy. So, maybe the weight doesn't matter?

I have a Seagull Edge 540. It's a .61 to .91 2 stroke sized, .91 to 1.20 sized 4 stroke. I have an OS .91 surpass on it, and it is underpowered and flies like a brick. If I put a 1.20 4 stroke on it I don't know if the nose would rise. It's just really heavy. So I guess for this situation, I need to use a 2 stroke for power, because they weigh less? And I don't know what 2 stroke to use because I don't have one of my own that is this large. But I'm back to the same question about 2 strokes. I could go round and round all day about this. If HP claims can't be trusted, then I should just pick one.