How Big of a Deal Swapping Out Power on a 25 OB?
 

I've had my eye on a 25 PP OB that was originally rigged with 2 X 225ProMax's EFI's. Would prefer an Opti powered boat and Mercury only offers the Racing Division Optimax 250XS's with 20" mids and counter-rotation.

I'm assuming the 225 powerheads were not as wide as an Opti 250XS powerhead and also that these two different engines have differently spaced bolt patterns with the Optis being mounted a few inches wider to allow full steering.

How big of a deal is it to plug the original mounting holes in the transom and rehang the new Opti's?

Any feedback is greatly appreciated. Thanks!

Not bad.
 

I just did it for the 2nd time on my 2nd twin O/B 24' Sonic. It had 3.0 liter 225 EFI Mercs and now has 3.0 liter JohnRudes. Had to expand the center to center by I think 2".
Most of the 25' PP's I've seen have the motors mounted to the transom so that'll make it easy. Pull the motors and glass in 1/2" dowel rod in the existing holes and re-drill.
Good thing is, I believe that will be a direct bolt up conversion. Control cables and harnesses should mate right up.

Glad to help if I can. pm me for my # if you have questions.

Gary

Thanks!
 

Yes this PP had directly mounted to the transom. Good info. Thanks

why the pro-max to opti conversion? just curious?

Not sure about the opti's due to smartcraft, but any other 3 litre merc will go in the same holes, and have the same wiring as the promax's. Not sure if the powerheads are bigger or not, but since center to center is not changing, I dont think it would be that big of an issue.

Probably fuel mileage and warranty

The promax to optimax motors will bolt right on the transom with no problem but u will have to buy an adapter for the boat harness since the plug in from the boat harness to the engine harness are different. If u dont want to buy the adapter u can buy new harnesses for the boat but the adapters are less expensive.

Good to know, as I may eventually switch to an OPTI from a 250 EFI, will this adapter work?

The boat was originally rigged with older ProMax 225's that required 91 octane, I was thinking that Optis were the way to go with this installation. The adapter vs. new harnesses info is very helpful. Thanks

yes, the adapter will work. i will which too one day when i retire from these pair of 300x. i dont know when though. :bananalove: