mercruiser 140hp--has the question ever been answered?

[frmron]

I'm a newbie to this forum and have spent some time over the last few years reading as much as I can in this forum. The info is priceless and I can see there are many good knowlegeable boat guys here! I'm a GM World Class tech myself so I do "understand everything I know about this" but now I really want to learn.
I can't find where or if the discussion was put to bed about the Mercruiser 3.0L. Specifially what's the mechanical differences between a 120HP and 140HP.
I own a 1986 Searay Seville with a 120HP and am looking for any HP advantage I can squeeze out of the 3.0L.
I searched and read a lot of threads, but I haven't read about the magic bullet yet. Any suggestions? Thanks!

 

[Bondo]

Re: mercruiser 140hp--has the question ever been answered?

The 120hps are 2.5l, 153cid motors.......

The 140hps are 3.0l. 181cid motors........

There's No Replacement for Displacement...............

 

[frmron]

Re: mercruiser 140hp--has the question ever been answered?

Ya but,...........
There are 3.0L 120's and 3.0L 140's
Is that all just marketing B.S.? or is there more to it like GM did with the Northstar vs. Aurora engine? In GM world, there are tons of examples where displacement may be the same, but with a combo of different parts, they add or subtract HP.

 

[Bondo]

Re: mercruiser 140hp--has the question ever been answered?

The Head has under gone Several changes over the years,......

I've seen them with Little Bitty ports,+ Great Big ports,......

But when you're starting at just over 100hp,.......10, or 15% Don't amount to Squat......
The actual Preformance differences between the 120hp,+ the 140hp is Minimal at Best.........

 

[Jeremy420]

Re: mercruiser 140hp--has the question ever been answered?

The Prop makes a difference, certain props run better than others.. Get a cupped prop if you don't have one on.. I really like my hustler on my 3L.. With this engine I think Propping correctly for the conditions is very important to get the desired outcome.. But you probably knew that part..

I have been wanting to put a larger air intake filter on mine, a "Tornado" or different air filter would be cool! Also have an idea to put an inline blower on my intake side and pipe it right up under the intake so I get cold air induction..


Hey have you guys ever heard of adding pure acetone to gasoline to improve efficiency and fuel burning. The acetone cracks the fuel and makes it atomize better, improving gas mileage and performance. You add 2oz of acetone per 10 gallons of fuel.. I am trying this in my older truck to see what happens and I notice more power... I think..

Not sure if it would harm any of the marine engine fuel components - any ideas guys?

 

[Bondo]

Re: mercruiser 140hp--has the question ever been answered?

You're Both Nuts,.......

Enjoy your Boat,........

If you want to Go Faster,......... Buy a boat with a Bigger Motor........

The Fancy Scamcy Air Filter will get you Nothing, but a Dent in your Wallet......
The Acetone additive will Probably get you Nothing but a Blown Motor........

 

[mkpj1]

Re: mercruiser 140hp--has the question ever been answered?

2 OZ Acetone to 10 gallons will probably do nothing. My dad was an old racer who make his own fuel additive for cleaning purposes and octane boost. IE....having a high compression motor....you need higher octane to limit detonation. Your own mixture would also help at the track. It usually comprised of a mixture of toulene, paint thinner, and ATF(for cleaning). Not any different than the expensive stuff in an auto parts store. the ratios are much higher than you suggest above and as Bondo suggests, really does not apply to your application as your motor is not built for it.

I would keep her stock as Bondo suggests....keep her tuned......and pick the proper prop for what you want to do...ie...skiing cruising. Notice I didn't put racing? The 120/140 was never...and never will be....a racer. Fact is, You could propbably figure a way to boost HP but your hull couldn't take it as I think it is designed for you 120/140.

Ahhh, Just listen to Bondo. This guy along with Don S. and a few others here preach the gospel and I am very thankful for their wisdom!

 

[Don S]

Re: mercruiser 140hp--has the question ever been answered?

Ya but,...........
There are 3.0L 120's and 3.0L 140's
Is that all just marketing B.S.?

There were never any 120's that were 3.0L engines, they were the 2.5L

I have been wanting to put a larger air intake filter on mine, a "Tornado" or different air filter would be cool!

Marine engines MUST have CG approved flame arrestors, NOT air filters.

I'm with Bondo on this, if you want to go fast get a boat with a different engine and drive setup, or spend the money and remove your present engine and drive package, and put in something bigger. These are boats, not cars. You will need at least a 10 hp increase in the engine to gain mayby 1 mph.
To get on plane in a hurry, you need torque, and that is going to be hard to do with a 2.5L engine.

 

[AEROCOOK]

Re: mercruiser 140hp--has the question ever been answered?

The 120hps are 2.5l, 153cid motors.......

The 140hps are 3.0l. 181cid motors........

There's No Replacement for Displacement...............

Sorry to jump in, but I have a question... Just bought a 1974 boat wit a Mercruiser 140 (according to the plaque on the dash board) the motor is an inline 4 cyl. which I believe is a 2.5?? were 2.5s of this vintage evere rated as high as 140 hp?

 

[Haut Medoc]

Re: mercruiser 140hp--has the question ever been answered?

Is your boat 14 feet long, by chance?........​

 

[AEROCOOK]

Re: mercruiser 140hp--has the question ever been answered?

Please pardon my ignorance, I didnt realize that the 3.0 was also an inline 4 cyl... my boat is 19 feet. and it has a plaque that says "Mercruiser" 140 on the dash, so I must have a 3.0.

 

[Skid-joe]

Re: mercruiser 140hp--has the question ever been answered?

About the debate of Hp for the 3.0 I/O.

I can tell you that my 3.0 is rated at 130hp, 1988 Thunderdraft Nova.

I have all original literature from previous owners,( and the spec sticker on the engine says 130HP).

I am not looking to modify or anything but am curious about the difference if it is really 10 hp or if it BS......

thanks in advance...............................joe

 

[tommays]

Re: mercruiser 140hp--has the question ever been answered?

Somewhere in the middle of this HP mess the switched from rating at the crankshaft to rating at the prop shaft

I am sure this is a reason for a LOT of the difference


Tommays

 

[whywhyzed]

Re: mercruiser 140hp--has the question ever been answered?

were 2.5s of this vintage evere rated as high as 140 hp?

no, in fact some 6 cylinders of that vintage were only rated 140 HP

 

[Don S]

Re: mercruiser 140hp--has the question ever been answered?

no, in fact some 6 cylinders of that vintage were only rated 140 HP

1963, Mercruiser 194 Cu.In. IL6

 

[Skid-joe]

Re: mercruiser 140hp--has the question ever been answered?

I am talking about the 4 cyl, 3.0 I/O 1988, if 88 is vintage so be it.

Tommays comment would make sense, but I am wondering when this came into effect........

So again, is the difference from 130 to 140hp only a technical writing stand-point or is there two 3.0 litres engines.

Anybody here has the 3.0?......what is yours rated at??? I am talking the 4 cylinder around 1988........

Thanks for any response......................joe