how can I add HP to my 120 mercruiser?

Azlo

Senior Chief Petty Officer
Joined
Jun 21, 2009
Messages
706
I have serached the forums on how to add hp to a 120 mercruiser but havent been succesfull . are there any aftermarket parts?
 

fat fanny

Lieutenant Commander
Joined
Feb 9, 2006
Messages
1,935
Re: how can I add HP to my 120 mercruiser?

azlo there is only on answeryou will find on iboats to that ? and it is go bigger the 3.0 is a little work horse and is not designed to do more than what it is already. keep it tuned and it will last. believe me the question has been asked before and you will here the same thing I'm telling you exspect 35 to 45 mph max if shes running right and thats about it.
 

Azlo

Senior Chief Petty Officer
Joined
Jun 21, 2009
Messages
706
Re: how can I add HP to my 120 mercruiser?

dam the bad luck!
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
Re: how can I add HP to my 120 mercruiser?

azlo there is only on answeryou will find on iboats to that ? and it is go bigger the 3.0 is a little work horse and is not designed to do more than what it is already.

Just to clarify - the 3.0 IS bigger than the 120. The 3.0 is considered the 140, while the 120 is smaller - 2.5 liter if memory serves. There is a considerable difference in performance between the two. My dad had an old boat that had a 3 liter on it originally - it ran reasonably well. When that engine died, he replaced it with a 120 - big mistake. It wouldn't get out of its own way!

The good news is that if you find a used 3 liter, you can replace with 120 very easy as everything will bolt over.
 

Azlo

Senior Chief Petty Officer
Joined
Jun 21, 2009
Messages
706
Re: how can I add HP to my 120 mercruiser?

Well that good news, so I can just find a 3.0 merc and it should just bolt on. Good,,,,what about gearing in the out drive do you guys think i need to change as well,,,it a pre alpha.

thanks Fishermark.
 
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