View Full Version : 25 liter Merc 150hp to 200hp conversion

05-26-2003, 08:55 AM
" I have a 1993 ProCraft 180 combo (Fish and Ski) with a 150hp Black Max. I've tried several different props but all I can get is 55-56 mph. I'm turning 5700 RPM with a 22 pitch chopper. I would really like to get the boat in the 65+ mph range. Bow lift seems to be a chronic issue with the Fish and Ski style of boats. I've considered installing a Jack Plate but it seems to me that with the driver and passengers sitting so far foward, the gains will be minimal. So my question is, what is the difference between the 150hp and 200hp models? I'm pretty sure in the 1993 model year they were both built with the same 2.5 liter block. What is it going to take to convert this puppy to 200hp specs? Any help from the guru's would be much appreciated. Thanks. "

05-26-2003, 10:31 AM

You would have to have the block bored for the bigger diameter pistons used in the 200. I'm not sure that you can bore the block that you have enough for this.

You would need different heads, carburettors, and pistons. Depending on which gearcase you have, you might need to replace that also.

Just a guess, without the gearcase, you would be in the $3000 price range.


05-26-2003, 11:16 AM
Loose that prop get a prop with stern lift at your Mercury dealer