Ok here we go, please advise! Another Power issue!

[NathanY]

I bought a boat, that has a 115 merc on it (1978 model), but is only rated for a 95hp. Here is my delima, I have always been against overpowering boats, but the 115 and the 90 are the exact same motor and weigh exactly the same at 300lbs, but a Johnson of the same year in a 85 hp weighs 312lbs. So if I power down, I gain weight, if I stay the same, I am overpowered. Is this even worth worrying about? What should I do?

 

[bob-o p]

Re: Ok here we go, please advise! Another Power issue!

if it floats and the transom isn't rotton or weak i wouldn't worry, just keep an eye on it <br />good luck!

 

[letsbarbq]

Re: Ok here we go, please advise! Another Power issue!

nathan, dont lose sleep over it. if its not broke, dont fix it. I have a boat that had a 150 and now i have a fat pig 225 on it. talk about adding a few pounds.

 

[snapperbait]

Re: Ok here we go, please advise! Another Power issue!

Peel the 115 sticker off and put a 95 sticker on.. <br /><br />Seriously, I'd leave it as is.. If it seems to be overpowered, back the timing off at WOT a couple degrees..

 

[JB]

Re: Ok here we go, please advise! Another Power issue!

Ahoy, Nathan.<br /><br />Like you, I usually object to overpowering. If you were making a choice between the 90 and the 115 I would advise you to go with the 90.<br /><br />But that isn't the case. You have the 115, which is a more highly tuned version of the same basic powerhead. Except at WOT, you probably wouldn't notice the difference.<br /><br />You might want to change the decals to avoid complaints from nitpickers like me, but I think you have a good engine and ought to keep it.<br /><br />Good luck.

 

[ob1jeeper]

Re: Ok here we go, please advise! Another Power issue!

Nathan,<br />Couldn't agree more with those who have replied thus far. Generally speaking it is indeed a poor idea to re-power with a powerplant which is larger than what the plate on the hull is stated to be able to withstand.<br /><br />However, the difference you're referencing is only 20hp, and since hp rating systems have changed from crankshaft to propshaft, you'd find that new 90 hp motors (rated at the prop) would probably be higher output that the older (like your 1978) if it were to be measured at the prop, instead of the crankshaft.<br /><br />But... If you are still concerned, get your 115 "dynoed", to see what it's really putting out...<br /><br />Good Luck, Obiwan Jeeper

 

[NathanY]

Re: Ok here we go, please advise! Another Power issue!

Well I tell you what Id really like to do, that is take and either sell this motor, or trade it for a 70hp 3cylinder JohnnyRude of the same era, I have no want or need to go fast. Boat will run 58 across the water(gps), And I dont need to go that fast. Some will say it is nice to have the extra HP when you need it, but I say it is better to have the extra gas.

 

[what200]

Re: Ok here we go, please advise! Another Power issue!

your 115 became the 90 later in the mid eighties. There are only minor differences between the two. Buy a 90 wrap around and a sticker for the lower cowling if you feel you need to.

 

[what200]

Re: Ok here we go, please advise! Another Power issue!

You might want to change the decals to avoid complaints from nitpickers like me,

So are you saying that you would complain about my hydrostream (145/165 rating) with a suzuki 200 (hopefully more after heads are cut) or my aluminum bay boat (100 rating) with a 150.

 

[G DANE]

Re: Ok here we go, please advise! Another Power issue!

Hi Nathan<br /><br />Please tell us which boat you have and which propeller on motor - <br />I am about to mount a 1991 115 ( prop rated ) on my 17runabout which is a deep-V weighíng 425 lbs + motor+crew+gear/gas/tank. Would like to get an estimate of speed.<br /><br />Dane

 

[NathanY]

Re: Ok here we go, please advise! Another Power issue!

It is a 1978 Cajun 16ft with a 1978 Merc 115 with a 19pitch turbo type prop, manual jack plate. I could very easily make the boat go faster than that. I have a set of 150 carbs that I could put on it,but probably wont.

 

[what200]

Re: Ok here we go, please advise! Another Power issue!

I doubt the 1500 carbs will gain you any power. The differences between the 900,1150, and 1400/1500 inline is mainly port size & timing and the power port in the piston & block that the 1400/1500 has.

 

[G DANE]

Re: Ok here we go, please advise! Another Power issue!

Nathan - how much does it weigh and how is the bottum ?<br /><br />Dane

 

[NathanY]

Re: Ok here we go, please advise! Another Power issue!

Putting the 150 carbs will infact give me more power, I have dont this on three other motors, my dad has already squared the ports (what he said I dont know what it means), the boat dry weight is about 500lbs, that motor weight 300lbs. The lower unit is in good shape, does not leak any oil, and there is and never has been any water in the oil.

 

[G DANE]

Re: Ok here we go, please advise! Another Power issue!

I guess he means machining ports from round shape to almost square, increasing port area, letting more gas/air mixture in - espacially if you change carbs. But then i guess you have a 130 perhaps and no 115. It seemed to mee 58 mph was a lot of speed with an old 115 !! I hope I will be able to gothat fast too.