Johnson 60 to 90 HP jump

[Bent Creek]

Hello,
I am currently re-powering from a 1996 Johnson 60 to a 90 hp. Not sure of next make, either an 90 ETEC or Mercury ELPTO 2-stroke 90hp. I have my 60hp on a Crestliner 1860, 6 degree Mod V-hull Jon Boat customised. Total weight with me and full gear is about 1300 lbs. The only prop I have been able to use so far is model # 176214 (14x17) Aluminum and wore out with dings and pits but it seems to be ok. It moves me at 35 mph at about 5500 rpms. My questions are;
1) Will the Prop need to change with the added HP?
2) (Stupid Question) but does it matter if the new motor is an ETEC or Merc? I know a merc needs a merc. but does the pitch and size require changes? I do not think so, just checking to make sure!:%
3) would the same prop I mention above provide more speed/power in Stainless?

I have used a smaller diameter Prop from my other V-Hull boat and it did nothing but cavitate..

Thanks
Nickd

 

[Silvertip]

Re: Johnson 60 to 90 HP jump

You should be able to run a 21P on that boat with a 90 HP motor. At least that's what I would start with. Unless you are after every ounce of performance and every MPH is of extreme value to you, you do not need a stainless prop. Bolting on a prop of any type does not magically increase the "power" of an engine. It can only affect performance characteristics such as holeshot, wide open throttle speed, bow lift, stern lift, etc. Bolting on the wrong stainless prop may result in poorer performance than a correct aluminum. Work with the dealer selling you the engine. They may provide some props for you to try. The object is to use the prop that allows the engine to operate at or near its recommended wide open throttle RPM. That will determine what your maximum speed is. Too much pitch and the engine is being lugged. Too little pitch and the engine over revs. Do your research carefully.

 

[Texasmark]

Re: Johnson 60 to 90 HP jump

Heads up on engine selection. I have a 3 cyl 2 cycle 90 Merc. Engine is beatiful in all respects except propping for a light boat. Since the gearbox is 2.3:1, for a light boat it takes a lot of pitch. If you get that pitch in SS for performance, course you do with that engine on a light boat, you get "Clutch Dog Rattle" at idle speeds and it drives you nuts.

If you use an alum prop or low pitch SS on a heavier boat then you would work long and hard to improve over the 90 Merc.

Mark

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

Thanks guys, great advise. Currently, the Johnson 60 I have is mounted in the second hole and sits about an inch off the Transom with the lower lined up with the slight 6 degree bottom of the boat. Is there a bennefit to raising or lowering the new 90 hp motor with this type of mod V hull?
Texasmark, I see you run a similiar style boat, did you work out the "Clutch Dog Rattle"? I don't really know what that means as much of what you both were talking about is a bit over my head.

Thanks for advise
Nick d

 

[Texasmark]

Re: Johnson 60 to 90 HP jump

Yes what you see in my Avatar is the current boat with the 90hp.

The rattle is a banging and clanking you get at idle speeds (comes out of the lower unit gearbox), or slightly above, with the shifter in F gear only and it is caused by the way they designed the shift mechanism and related gear interfaces for F gear.

I looked at the older OMC shifter (haven't seen a new one) and it is different and probably doesn't make the noise....I don't think it is spring loaded like Merc is.

Lower hp engines or engines with more cylinders, or engines with a 2:1 gearbox (running a proportionally lower pitched, hence lighter prop) probably won't have the problem. My last 3 cyl was a '75 70 Rude and I didn't have the problem and had that sucker pitched (really too high)...but the 70 was lower hp meaning each bang of a piston was less, and as I said, OMC has a different shifter setup.

Is it resolved for me? Not completely. The the plugs I just installed did help significantly by firing more evenly at idle. But like I said, I like everything else about the rig and I can work around this.

HTH

Mark

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

Thanks Texasmark. I think I decided on teh 90 Etec. I found one for $6,500 new in crate at a fairly local marina here in Michigan. He said he has a complete line of props at various pitches and assured me he'd find the best fit for my boat. Allot of money, a mad wife, but I spent allot of time and money modifying my boat and have wanted to power and prop it right for 4 years now. I hope I'm happy with the motor choice and believe I will be. I was considering the Mercury 90 ELPTO but for $800 more I have the Etec Option.

Thanks
Nickd

 

[walleyehed]

Re: Johnson 60 to 90 HP jump

20" or 25"? (shaft length)

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

20" shaft length

 

[walleyehed]

Re: Johnson 60 to 90 HP jump

OK, that tells me you'll be using 13 spline props just like your 60...
I guess "my" next question would be; what are you looking for as an ultimate goal with this combo..speed?

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

Yeah, I like to go fast. But I have allot of gear and add ons to the boat at times, such as Fiberglass hood (front deck cover) approx. 100lbs. Blind and Frame work Approx. 100lbs during Duck Season. Plus another guy, dog, guns, deeks, heater, frying pan, coffe pot, scrambled eggs, bacon and toaster. Not to mention a TV at times. As you can see, I like to rough it out there.
So late fall and early winter I'll have an extra 800 lbs in the boat at times. 8)

Summer time, it's pretty light, Poling Platform,125 lbs. punt pole and me 300lbs. Sometimes on of the kids 100lbs.

The boat hull dry weighed 600lbs or so new. After I modified it (see avatar) I guess I added around 300 lbs to it in fiberglass.

Do you think I'll need 2 different props for both seasons? will this have any adverse effect on the engine computer?d

 

[walleyehed]

Re: Johnson 60 to 90 HP jump

2 props would be a best-case situation. If Idling around in a bunch of stumps/debris when getting to your fav duck hole, I'd go with SS because if you hit a stump or tree while puttering around in the timber, it will just kill the engine insted of bend a blade like would happen to aluminum. Pitch should vary about 3 inches between the 2 props, maybe even 4" when loaded. It'll be a case where you'll want to test a prop of known pitch in good condition to get a base-line so we know which direction and blade design you need.

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

thanks, i'll load it up and test it both ways. I'll likly get 2 props.

d

 

[Dhadley]

Re: Johnson 60 to 90 HP jump

Only 2? Good grief! I thought everybody had at least 5 or 6........per boat that is.......

 

[walleyehed]

Re: Johnson 60 to 90 HP jump

That's right DH..I forgot to tell him that the summer props were different than the winter props...not to mention spring and fall....
Bent creek, I'm sorry, but we're gonna need atleast 4 to test with......8)

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

Glad your all having fun with this!!!. That's ok, I think I'll start out with the Prop that gets me moving in the Spring when I get the Etec 90 on the boat. If I need another prope IN THE FALL, I'll be sire and tell you all.

By the way, as I have everything but "the kitchen sink" sticling off this boat, I can build a stick of sorts coming off the gunwhale that I can stack all of my props over and color code them per season. Yeah, that'd look pretty cool out there. 8)

Thanks guys. d
Nick

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

Well guys I bought the 2006 90 Etec this past weekend for $6500. can't wait for May to mount it and hit the water. Thanks for teh help

Nick d

 

[walleyehed]

Re: Johnson 60 to 90 HP jump

Keep us posted...and we want to see that rack of props mounted to the side of the boat.......8)

 

[Bent Creek]

Re: Johnson 60 to 90 HP jump

Will do Walleyehead, thanks for all the advise on all my posts.

Nick d