Mercruiser 3.7 swap to??

Hello everyone. I think I blew my engine because I'm an idiot. I have a 1989 monterey 19' cc with mercruiser 3.7L inline 4 (165hp).

The fuel pump became loose on the 4th and slowly leaked oil throught the whole day until we were on our way back in when we heard the low oil "ticking" and eventually what I think was rod knock. We filled it back up with oil last night after securing the fuel pump and launched it. It sounded fine at idle and ran smooth under 2000 rpm, but as soon as we got on the throttle to plane it, we heard the knocking sound again.

So I'm pretty sure the engine is blown. My question is, what is the most cost affective way to fix it?

The boat was already underpowered - it had a hard time getting on plane with just 4 poeple on it; so I really don't want to spend thousands to rebuild the same engine and still have an underpowered boat.

Would it be much more expensive to swap in maybe for merc 4.3 or one of the V8s?

Thanks for your help!

 

You can swap for a V8 or V6 with some work. The engine mounts have to be modified and you need a Y exhaust pipe. The 4.3 will have about the same HP and a V8 will probably need a different gear ratio.