120hp to 140hp??

[birdy3897]

I am considering repowering my boat next spring and going from the 2.5/120hp to the 3.0/140hp motor. I can have my 2.5L rebuilt for about 1200 bucks or I can get a new 3.0 for about 1800 bucks. Has anyone done this? Wondering if there will be enough differnce in power to justify spending the extra 600. I realize that power on the water is expensive, but If I won't notice it much than I am thinking of sticking with a rebuilt 2.5L.

 

[rodbolt]

Re: 120hp to 140hp??

the 2.5 was offered in a 140 HP version as well. I really doubt you will see a big increase other than the 3.0 is about 28 cubic inches larger<br /> you may also find a big difference in the intake ports from the 120 manifold to the 3.oL head. some were incompatible and will nessitate the use of the correct manifold. not a problem if your replacing it anyway. I think marine power sells a drop in complete for about 3000. comes with about everything but a battery. and they have a drop in EFI 3.0 thats rated at 180 HP.

 

[trog100]

Re: 120hp to 140hp??

what kind of a new 3.0 do u get for your 1800.. if it really is a new GM motor after 2000 or so they all come with bigger 14 inch flywheels with some of the later (before 2000) 3.0Ls i think u could just use your older smaller flywheel plus drive coupling on the new motor but with the earlier motors it isnt that easy..<br /><br />if u do go for the 3.0L just make sure the stuff from your older 2.5 motor is gonna fit.. else it might end up costing more than u think<br /><br />trog<br /><br />ps and rodbolt.. tween 89 and 94 they also sold a 3.0L which was rated at 115 horse.. just to fill in the gap when they stopped selling the 2.5 i dont think their rating figures always mean much... he he.. i would think that the 20% extra capacity would thow.. not much but some the 20% capacity differnce matches the 20% power differnce tween the two sizes..

 

[birdy3897]

Re: 120hp to 140hp??

 

[whywhyzed]

Re: 120hp to 140hp??

A friend of mine put a 3.0 into his 16' Century skiboat. A big improvement over the 2.5 for holeshot.

 

[birdy3897]

Re: 120hp to 140hp??

Hystat, what kind of top speed where you guys getting with your boat? Mine is a 1978 Imperial 2.5L tri-hulll. It is a heavy boat and I get up around 31-33mph. Just curious how fast your boat went. Also, did you notice an improvement on top end at all, I noticed that the operating range for the 3.0L is about 2-3 houndred rpm higher than the 2.5L.

 

[DHPMARINE]

Re: 120hp to 140hp??

Don't forget to compare rebuilt 120 and new 140.<br /><br />I also think you will see 120 parts get harder to find.<br /><br />DHP