The Cal boat fire kinda got me going down the rabbit hole. Got looking at some outboards in the 400-450 range, Yamaha by default.
f450- 4 stroke 32 valve, dohc, 60-degree v8, 5559cm3 displacement, 96x96 bore/stroke, 331@5500(max shaft output@rpm)
f400—————————-same specification as above till——————————————, 294@5500

Why do we have different outcomes am I just being stupid, what am I missing? never been a gear head but displacement, bore, stroke and rpm same but different outputs

Computer chips probably. Only difference on several smaller outboards is the chip.

Yep. My understanding is it's the same exact motor, just tuned differently. They do this in the smaller sizes as well.

That’s what I figured, never really thought about it

The only difference is between my Yamaha 150 and a Yamaha 250 is a computer chip. All other parts are the same.

I know it’s about money and stuff but it seems like you are handicapping the motor

I’m not saying you are wrong….its highly likely you know more than I do, but wouldn’t the injectors have to be bigger? Seems it’d have to have more air also? Same motor, but with some slightly different parts? 100hp is a huge jump! Just my thought.
I’ve got a 2 stroke 40 Yamaha. I was told just changing out the carb could make it a 50 or 60. Then a carb and exhaust manifold?? (maybe that was the part) I could have a 70. They were the same motors though.

9 HP same as 20HP Suzuki w/ parts. They certainly do this type of stuff. How adventurous you are is another matter.

Not correct 200-300 are the same your 150 could be tuned to a 175.

That's right, 150 and 175 are same. It's all about you paying for the horsepower.