Prop size for 253 convicor

[fast willy]

Just finished boat & it has a worked 454 putting out 525 hp. Know I need to know what prop to run. Should I use a 4 blade 3 blade & what size, do you think a 27 4 blade is to much. We are new to the go fast boats so any advice would help, I will try to post some pics it is completely redone with a mid cabin setup pretty sweet looking, oh it is a 94 253 Convicor.

[bigsbetter]

If the horsepower is 525, a 27 Hydromotive 4 blade should be a good start. They're 15" diameter and most have a solid welded hub. I'm running a 28 Hydromotive 4 blade with a 330 horse 454 w/ a 177 blower. Probably around 475-500 horse in a 251 Convincor. I'm turning about 4400 rpms. With your built mag what kind of rpm are you wanting to turn ? Maybe around 5000? I would strongly reccomend using Mercruiser High Performance gear lube in your outdrive. It will hold up and not break down under the friction and heat you will creat in the drive.

[fast willy]

Bigsbetter thanks for the reply, it is actually 523hp on the dyno. I would like to run around 4800 to 5100. I can get my hands on a 27 4 blade so I will give it a try.