upgrading mercury 150EFI to a 200 or 225

[poorox]

okay I have what is probably a stupid question, I can get a 96 model 150 EFI at a great price(just about free) the motor has 1 burn't piston so, I'm considering rebuilding it or just repairing the one cylinder. What I would like to know is what it would take to convert it to 200 or 225? The motor is going on the back of a 19ft. blazer bass boat and is going to be used for fishing and not racing, so it must be reliable. any input would be greatly appreciated.
Thanks,
Poorox:confused:

[sosmerc]

Pretty expensive to get a bit more horsepower for something that is just going to be used for fishing. But the ecu can be re-curved to match whatever level of modifications you are shooting for. Heads can be shaved to bump your compression for more power...and then you'll have to run higher octane gas. Port work and exhaust chest modification as well as switching to 200hp ported pistons and intake mods for better air flow. Or maybe just find a 200 or 225 2.5 litre block of similar model year and put in new pistons and reprogrammed ecu. All it takes is time and money.
The 2.5 litre 150 EFI is a pretty darn good motor as is. Prop it to turn 6000 and it should deliver good performance and reliability.

[poorox]

Thanks for the info. You've got a very good point,I will probably just stick with the stock 150. Reliability is more important in this boat than speed. My Dad had this boat with a 175 mariner and it ran great. He's now running a 200 optimax xs on it, but the motor's going on a new blazer. I had a 20Xd bullet with a 225 promax, but I had some medical problems and sold it. He's giving me a son's discount on the boat and an old bass club friend had the engine on his boat until it burn't the piston, he replaced the engine and is letting this 150 go real cheap. Both boat and motor were purchased at the same time and both are one owners and I know both owners well. What about sleeving/replacing just one cylinder and not all six? Any input there?
Thanks,
Poorox;)

[sosmerc]

It is perfectly ok with outboards to fix a damaged cylinder and leave the other cylinders alone if they are in good shape. You can bore .030 over standard on that engine. If the cylinder won't clean up at .030, then you can sleeve it.
But I would have a competent machinist measure the bores carefully, and if they are more than .003 out of round, you'd be wise to repair them all. Nothing runs better than an engine with nice round cylinders and properly fitting pistons!!
I've gotten good service from Mar-Fab. Talk to Kurt Phifer
931-738-2815

[poorox]

The info is greatly appreciated. There is a excellent mechanic next door to where the engine is at now, I just haven't been able to talk to him yet. This deal came to me pretty quick and I wanted to get some input from the members of this board, I have been reading it for a couple of weeks now and I was impressed, and you didn't dissapoint. Also I didn't have the patience to wait until I could talk to the mechanic.
Thanks, again:o

[MARINER RACING]

Put a set of 200 carbs on that thing and raise the port height
youll have a 200 just as reliable as what you have now
it will cost some $$$ but sometimes its worth it if you have a good foundation to build on, and you got the motor cheap
any questions you can give me a call at the shop 561 687 3636...Jay