So built up 588 Apache motors where 830 HP and 900 lbs torque now 930 hp and 1000 lbs torque have Mercury 4 blades 17 x 27 on now should i go to larger prop and if so what is suggested size.

tks

Sounds like fun! 😎

Try this

https://www.go-fast.com/Knowledge-ba...eed-calculator

and then this

https://www.go-fast.com/Knowledge-ba...your-prop-slip

That would depend on the rpms for peak hp and torque on the new builds vs the old ones.