90HP or 115HP

[Bent Creek]

Hello,
I have a 1860 Crestliner Mod V Hull with a 1985 Johnson 70 HP on it. At WOT this motor pushes my boat at 32 MPH (GPS) Original the boat weighed 650lbs I believe and it clocked at 38MPH again GPS. I added a lot of wieght to it with modifications approx 300 lbs.
I am in the market for a new motor and am concidering either a 90 or 115 2 stroke. Mercury or as recommended by other an ETEC.
First, will the difference in speed from the 70 I currently have and a 90 be disernable?? if so approx. what type of speed gains could expect?d
Second, Is the difference between the 90 and 115 of either brand be worth the investment? What speed gains could I expect from the 115?

Thanks

 

[DJ]

Re: 90HP or 115HP

What is the boat rated for?

 

[Bent Creek]

Re: 90HP or 115HP

Well, it's rated for a 90HP. Just trying to see how much I can get?:$

 

[DJ]

Re: 90HP or 115HP

Well, it's rated for a 90HP.

There's your answer.

Overpowering it will open up a real can of worms, for the following reasons.

1. Your insurance company will disown you, if you have an accident.

2. The hull might not be able to handle it.

3. There is a big difference in weight between 90 and 115 models from numerous (not all) makers.

A 90 may give you five + MPH, with the proper set up. Maybe more.

 

[Texasmark]

Re: 90HP or 115HP

I was hoping that your rating would allow for the 115 which is a 4 cyl, not 3 cyl. I have had a 70 hp OMC with a 21P SS prop and it was smooth. I also have had 4 and 6 cylinder engines which were smooth.

I currently have a 4 year old Merc 90hp 3 cyl. I do not like it because with my 24p ss prop I get what's called "clutch dog rattle". The 3 cyl 90 is not as smooth as the 70 and I attribute that to the cylinders being so large and so few of them.....when a cylinder lights off you get a big bang and that shakes things up...as mentioned. With a high pitched, heavy prop, at idle rpm's you get this clanging and banging (not shift clunk, running noises while in gear). Shift to a low pitched SS or an alum and the noises go away.

The 90 has a 2.3:1 gear ratio. On the boat you mentioned you will be running a high pitched prop (to keep the rpm's in check at WOT) and with the right hull design will be up in the high 40's or so. I get 52 out of my 17' padded alum bass boat with it with the 24P Ballistic prop. The boat mfgr says the boat is 750# dry, plus 3 big batteries, livewell, 22 gal of fuel, anchor, tackle, me and all.

Don't know what advice to give you but just consider this a warning. You might be disappointed.....course you can stop the rattle by increasing the rpms to around 1000, but when you are trying to load onto your trailer, or are docking, you don't want to be at 1000.

Mark

 

[tashasdaddy]

Re: 90HP or 115HP

i get 42 with 3 people, 45 with just me. 1988 88spl johnny

http://i46.photobucket.com/albums/f119/tashasdaddy/bow.jpg

 

[Bent Creek]

Re: 90HP or 115HP

Guys thanks for the info. I wish I could go with the 115 but I surely would NOT want my insurance to dump me in a time of need. Important to concider, thanks. I had a blast building this thing, and am fairly happy with the power I have, the little bit more will surely help. If not, I'll sell the package to some other Duck Hunter and start over. Possibly a Roughneck or PolarCraft 16 footer. we'll see. Any preference to Merc basic 90 (not Optimax) or the 90 Optimax or a 90 ETEC?

Thanks again

Nick

 

[tashasdaddy]

Re: 90HP or 115HP

etec

 

[WillyBWright]

Re: 90HP or 115HP

I might not elect to go with a brand new motor on a 22 year old boat (is it the same year as the motor?). An 88 or 90 Johnson or Evinrude of that era would really wake that boat up. That way you can use your current controls and gauges. If you want new, get a whole package and trade yours in. E-tec or a 4-stroke.

 

[Bent Creek]

Re: 90HP or 115HP

No the Boat is a 2001 Crestliner Mod V Hull (6 degree) Jon Boat. I've had a 1986 70 Johnson on it and a 1996 Johnson 60 on it. The 60 has a bad Powerhead as of last summer so the 70 is temporary until I get a new motor. Are special controls, Guages needed for the Etec?

 

[Cricket Too]

Re: 90HP or 115HP

Yeah, but your gonna need new controls and harness, no matter what you buy though, unless you buy a used OMC, since your running and old OMC right now, you'll have to switch for a Merc or an E-tec.

The Merc options you listed don't compare at all to an E-tec. The Optimax is a DI system, but isn't close to the quality and performance of E-tec.

 

[Bent Creek]

Re: 90HP or 115HP

Yeah, the current controls are OMC and about 4 years old or so. I know they'll have to be changed out. Do you think the Cubic Displacement difference between the Etec 90 and Optimax 90 will have dramatic speed / power affects on this style boat?. The Opti has more cubic inches but a smaller lower unit, the Etec has 10 or so less cubic inches (? exaclty how much) but a larger lower unit. Does the lower unit size really make a difference, Gears, Prop size???
I read many forums and reviews and some say the 90 ETEC was MUCH more powerful than the reviewers 2 year old Optimax 90, Noticebly... and "that Etec was with a Jet Drive". Others say that the Optimax will always be faster as the displacement is greater. Just trying to get some straight facts or at least honest opinions. I like many (ALL) of the options offered by Etec. I do however want the most power and speed available.:/

 

[jimmbo]

Re: 90HP or 115HP

Check with your insurance company regarding over powering. 23 years ago I had a little boat rated for 100hp I took the crank rated Mercury 90 off and replaced with a prop rated 115. Gained 10 mph. Told my insurance company about the new engine being over powered, they increased my premium 30 bucks and didn't seem too concerned. It was noted on my policy that the boat was 15hp over powered. By noting it and accepting my money they assumed liability.

 

[Bent Creek]

Re: 90HP or 115HP

Great idea, i will check into it.
thanks

 

[Bent Creek]

Re: 90HP or 115HP


I know I should power the boat at the Max hp of the boat at 90HP (per Tag). But doany of you have any experiences good or bad with anyone stretching it just a bit to lets say a 115HP? I would expect Insurance to be an issue, possible boat / Transom stress and breakeage, buut do you all consider this little step up in wieght & power will effect the boat adversely? Would'nt the people who test and rate these boats have considered possible idiots like myself who just want more and back the rating down a little to "be on the safe side". I'll more thanl;ikely go with a 90hp. just wanting to get your thoughts.

 

[Bent Creek]

Re: 90HP or 115HP

i get 42 with 3 people, 45 with just me. 1988 88spl johnny

http://i46.photobucket.com/albums/f119/tashasdaddy/bow.jpg

What motor do you have and about how much does your boat weigh? Is your Johnny Alum. or Glass? Looks good. V-Hull, Mod V?

 

[jimmbo]

Re: 90HP or 115HP

Well the old inline sixes weigh pretty much the same whether they were 90hp, 115, 140hp, or 150hp. In actual use the lower power engines being the same displacement as the higher power model actually accelerated harder and quicker at low rpm. I found my 115 to have a weaker hotshot stressing the transom less than the 90. Once the rpms reached 4500 the 115 didn't run out of breath. That said not all 90hp and 115hp nmotors have the same displacementso... your results may vary.

 

[Texasmark]

Re: 90HP or 115HP

jimmo, I think the difference in what you are talking about was the gear ratio. As I recall the 90 had the 2.3 (which it still does in 3 cyl) and the 115 had 2.0. Do remember the sales brochures of the day talking about just what you said....lots of low end torque with the 90 and for faster, lighter hulls, the 115. Course I had a 115 I6 on a pretty heavy boat, but it was a Ranger and had a fast hull and didn't blush.

Mark

 

[jimmbo]

Re: 90HP or 115HP

Standard, the inline 6s after 72 had 2 : 1 gears, the 4 cylinder 85, 80 and 75 had the 2.3 : 1 case. For a couple of years in the mid 80s Quicksilver offered the 2.3 case as a high altitude replacement for the sixes but it wasn't a factory option.

pre 1973 115hp had a 1.78 : 1 gears

 

[Bent Creek]

Re: 90HP or 115HP

The boat is a 2001 Crestliner Mod V-Hull (6 degree). 21" sides. side console. I have added the approx. 300lbs of fiberglass structure along the gunnels and storage compartments within. The boat was about 600 lbs original, approx 350 lb 70 hp 1895 Johnson motor, 300lb structure wt. added, during Duck season and additional 200 lbs of blind, fiberglass hood for bow, decoys and guns. My 280 lbs or so, a buddy and a dog another 300lbs. The total wieght for the boat when loaded at its heaviest is about 2000lbs. The current old 70 hp Johnson pushes it totally loaded down around 28 mph (GPS). I'd like to reach at least 35 when loaded down this heavy if at all possible.
A normal summer time total weight would be around 1500lbs. Under this weight, the boat will go 34mph with just myself in the boat.

Before I modified the boat, this motor pushed me and the boat at 43 mph, super light, lots of fun.

I'd like to be in the 40 's with the new motor but I doubt the 90 hp will get me there. I guess I don't know for sure. My current motor has the stock Alum beat up prop on it. I imagine a stainless performance Prop would help some, but not sure how more I could expect from a prop upgrade alone.

Thanks