Cost of swapping a 115 for 150??

[-Marc V-]

I know this is kind of question with a lot of unknown varialbes, but wondering if anyone could give me a ballpark range of what it would cost to swap out a 115hp Merc 4 stroke 2007 for a 150 4 stroke. The 115 Merc has 199 hours and most of the hours, like close to 50% are below 2000 rpm. The 150 I'd want to swap out to would probably be a used 4 stroke with hopefully 200 or less hours and be a Merc, Yamaha or Suzuiki. Would also be willing to do an Optimax. Just wondering if anyone could ballpark it roughly...

I found a boat that doesn't come along all that often, but would just like a little more muscle on the back than the 115 on it now.

Thanks,

Marc

[MuskieJunkie]

If you can find a guy that has the motor you want AND is will to take your old one on trade he is going to give you wholesale value for your motor and charge you retail on the bigger one, plus labor.

Ballpark guess $3,000 to 5,000.

I would go online and find a local guy selling more than one used motor and give him a call.

[Kyhl]

I repowered my boat from a 115 4S to a new 150 4S last year. It was simple and the dealer was great but from now on, I will wait for the boat with the right motor. It is much cheaper in the long run.

Also, I wouldn't have done it if I did not plan to keep the boat for another 10 years.

I didn't look for a used option because it took me long enough to find the boat I wanted. Sounds like you may be in a similar position.

[lawdog]

What size is the boat? What are you using it for?

Realistically 115 horsepower will do just fine for the vast majority of boats. I can't fathom why people are wasting so much money getting more and more horsepower all the time, especially on fishing boats.

Good grief I regularly see $50,000 boats out there catching the same # of fish as $10,000 boats.

[delcecchi]

I know this is kind of question with a lot of unknown varialbes, but wondering if anyone could give me a ballpark range of what it would cost to swap out a 115hp Merc 4 stroke 2007 for a 150 4 stroke. The 115 Merc has 199 hours and most of the hours, like close to 50% are below 2000 rpm. The 150 I'd want to swap out to would probably be a used 4 stroke with hopefully 200 or less hours and be a Merc, Yamaha or Suzuiki. Would also be willing to do an Optimax. Just wondering if anyone could ballpark it roughly...

I found a boat that doesn't come along all that often, but would just like a little more muscle on the back than the 115 on it now.

Thanks,

Marc

What's the boat? I repowered from a 115 merc two stroke to a 140 suzuki and got about 3-4 mph max at WOT. The 115 had adequate power for my boat, mostly I wanted to get a 4s instead the the merc 2+2 two stroke.

[Kyhl]

Another thing to consider is the cost of changing manufacturers. When you change manufacturers you add costs for a different controls and in my case I had hydrolic steering that I wanted to keep without breaking the bank.

If you go used make sure they throw in the controls.

I know, it's easy to spend other people's money. I would guess a 2007 Merc 4S for a 2015 Merc could be in the neighborhood of $7k after trade in. So if you are looking at $5k for a used 150hp then it might be worth springing for new with a 5 year warranty.

[MuskieJunkie]

Just thought of another wrinkle to throw in. A lot of higher HP motors are the same block as their lower HP version, just with intake, exhaust and/or ignition differences. I guess you'd want to look at torque too.

For example, a 115 suzuki is the same block as a 140 so you will not see as big of a difference as a Yamaha 115 vs 150 which are different blocks.

[icehole10]

I have been considering doing the same thing. I have a 2002 17ft Mr. Pike d/c with the 115 4st Yamaha. I spent one whole afternoon at a marine dealership trying out different pitch props and I'm still not happy with it. The issue that im trying to cure is the way the boat rides in the water while on plane, at full throttle, with the motor trimmed up till just before coming out of the water, I can not get the front of the boat to come up at all. If you have the slightest bit of cross waves, its all you can do to hang on to it. The waves catch the front of the boat and make it difficult to control. I have started putting all gear in the rear of the boat, filling the rear live well and nothing in the front storage but life jackets and such. My biggest fear is more horsepower not helping, then it would be a big waste of money. If I could just talk the wife into a new one!!

[delcecchi]

Pitch of prop isn't the issue with "bow lift". It is the design of the prop. You should probably talk to someone who knows this stuff, like Soderbloom's or some other place. They might have some recommendations.

If you are planing well, a bigger motor won't help.

[Kyhl]

Ice, I'm curious what you mean by it not handling cross waves. I don't know any small fishing boat that can handle cross waves. This is probably a topic for it's own thread.

From what I could find the Pike 17 is rated for a 135hp max. You won't see much difference jumping up from a 115.

I agree with Del, look into different prop designs more than pitch. Props with more rake will allow the prop to have more grip when trimmed higher.

In my example earlier, I went from a 115 to a 150 on a boat rated for 175. There was a large difference in boat handling in my case because the 115 was under powered for my rig.

BTW, Marc, check your PM's.

[icehole10]

Its a bit hard to explain, but this is not my first boat and I just don't like the way this one rides. Maybe its the boat? It really doesn't have to be much of a cross wave, im not talking white caps or rollers. I have had a few other friends who own boats take it for a spin and they agree that the front drags to much. maybe that a better way to explain it. I know with my old oat trimming it up seemed to left the front of the boat at the same time, but the prop starts to cavitate before you get to that point. I feel the front of the boat needs to pitch up a bit more, that's why I was thinking horsepower. I've seen guys at boat landings with bigger boats and the same motor and spoke to them and they all seem to feel the motor is more than enough.

[Kyhl]

I dont know Yamaha props and it's hard to tell from that angle but the blade don't look like they have much rake which would create what you describe, cavitation with lots of room on the trim.

Look for something in the same pitch where the blade leans back farther (rake).

I have found the opposite works on my alumacraft, a prop where the blades are verticle works better (stern lift).

[delcecchi]

I dont know Yamaha props and it's hard to tell from that angle but the blade don't look like they have much rake which would create what you describe, cavitation with lots of room on the trim.

Look for something in the same pitch where the blade leans back farther (rake).

I have found the opposite works on my alumacraft, a prop where the blades are verticle works better (stern lift).

My thought was that a 115 ought to do the job on that boat. Mounting or Prop most likely the problem.

[BoxMN]

This is to icehole....

What hole is the motor mounted on? If you have enough bite with a specific prop, you can often raise the motor a hole, though it seems as if you aren't quite getting the bite you need - but it could be a combo of the two. The change in leverage will allow the motor to force the bow up wen it is higher, if you have the bite. IMHO Most dealers mount them too low because they sell them with carppy props, or buyers are too cheap to purchase a SS prop. They sell to the lowest common denominator. Heck, I even had them mount my pontoon 60 hp 4 stroke up a hole from usual, and it runs better. BTW you can raise and lower yourself with a half hour, a couple friends, simple wrenches, a floor jack, and a tube of silicone.

Try a merc trophy (i'd guess at a 17 or 18 maybe?...) if you can find one that fits and see if that helps. I don't think they make a Tempest that would fit, but the Tempest is awesome at the combo of handling plus bow lift plus speed for these style boats. Have heard good things about Vengence props but never tried one. Heck, get a hi-5 that fits (maybe a 18) and if that doesn't do it, you need a different motor. (Hi-5 is not great in reverse, but they are an awesome prop for handling and bow lift and general umph, but not the fastest.)

Most of my experience is with 2 strokes, and merc specifically, but we raised our 90 (years ago boat, SS 18" three blade) and were able to get better handling and speed and cornering out of the same prop. Also on our 150 we raised a hole (maybe 2?) with a Tempest and it is just awesome. If you happened to try a Laser prop (which many people do) that is not a good prop for this application so could be why you had poor results.

After driving boats with this size 2 and 4 stroke motor(s) I will however say that those saying their 4 strokes (of any hp) run great either forgot what it was like to drive a properly propped mid to upper-hp 2 stroke or never have run them Put a v-6 merc 135 opti (they don't make them anymore) or old style 2-stroke efi on that boat and it WILL be a totally different different beast, regardless of prop The extra cylinders ad displacement DO put a much bigger smile on a guys face, heh...

I personally think that boat and motor combo is lacking in hp in general, especially with 4 stroke (IMHO of course), but you certainly should be able to drive to without funky steering from normal waves.

Then there is peening the hull near the transom, but that is a bit more advanced and I am not the right guy to speak to it... I know there were several models of Alumacraft hulls several years ago that needed some peening adjustment due to porpoising when rigged with 90 and 115 4-strokes.

Anyway, good luck. I hope you get it figured out without spending too much $$. Should be able to with propping.

-edit - where is Hydro when you need him?

[Kyhl]

I agree Del.

Also, adding cupping also adds rake angle. Jay may suggest adding cupping which will add pitch and rake. The amount of cupping depends on your current pitch, prop, and rpm? Jay would know as Del pointed out.

When you call Jay, know your rpms, prop, and pitch and describe your problems. He will know what to do.

[delcecchi]

I agree Del.

Also, adding cupping also adds rake angle. Jay may suggest adding cupping which will add pitch and rake. The amount of cupping depends on your current pitch, prop, and rpm? Jay would know as Del pointed out.

When you call Jay, know your rpms, prop, and pitch and describe your problems. He will know what to do.

There is a guy over by Brainerd that is supposed to be good too, seeing as the OP is west. Brainerd Props I think is the place.

I got good service from Jay on my aluminum prop that had bad luck with a few rocks on Vermilion

[Mr.Seaguar]

Great looking boat Icehole.

[Down Deep]

Jay Soderbloom Prop's in Cromwell will come up with the right prop for this boat. I've been doing business with them for years and he has always hit the nail on the head. They will express ship a prop and its returnable for an exchange.

One of my fishing buddies had this same rig used on Lake Vermillion. Having had quite a bit of experience with this rig as a passenger and driver I can say this rig performed perfectly for a variety of uses including skiing and tubing. The sweet spot for cruising of this boat is about 38 to 40 MPH above that it gets a little light in the handling. My Pro V was the same way. He had a 17 pitch SS prop he got from Soderbloom's. I think about the only gain you will make is better hole shot and top end speed. If it were me I'd experiment with some different props and maybe change the mounting hole and check the trim range. You may save yourself quite a few $$$ doing a prop change.

[icehole10]

First let me say sorry for hijacking the post, second thanks for all the suggestions. I do know that the motor is mounted as low as it can be, as I looked at that and thought maybe it needed to be lowered. As it sits right now, if the motor is not trimmed all the way down when you go to punch it, it will cavitate, so you have to ease into it and then trim up once you get moving. As I said earlier, I spent many hours one day at a marine dealership in the Detroit lakes area, trying out different props, nothing really seemed to help as far as my original concern, but after your replies, I think that maybe something to look back into, someone with a little more knowledge on props. I'm going to run out to where its stored this weekend and get all the info off of both props that I have for it and start from there. Off the top of my head, im not sure what Rpm's it runs at, but i know top speed with me and some gear is about 33-34mph's Thanks again, hopefully that is all it is!

[Kyhl]

As it sits right now, if the motor is not trimmed all the way down when you go to punch it, it will cavitate, so you have to ease into it and then trim up once you get moving.

[delcecchi]

My 98 1775 pro-vee would do around 40, maybe 41 or 42 on a good day with just me and all my junk and a kicker and 3 batteries with a 115 merc 4cyl two stroke.

33 sounds like maybe over propped some. What is the RPM at that speed?

[icehole10]

I am getting the speed off of the GPS, and as far as the rpm's, its been a few months and my memory sucks, but I want to say between around 5k.

[delcecchi]

I am getting the speed off of the GPS, and as far as the rpm's, its been a few months and my memory sucks, but I want to say between around 5k.

OK, something isn't right. I looked at the performance bulletins at the Yamaha web site. WOT is in the range of 6000 RPM, and top speed was around 40. I had to look at Alumacraft since Lund isn't on there.

You can see a variety of boats with a variety of motors. They also tell which props are on them.

http://yamahaoutboards.com/owner-resources/performance-bulletins

[-Marc V-]

Thanks for all the replies! And sorry I was MIA for a bit. The boat is a Tuffy Osprey 1760 so she's a little heavier. Just picked her up over the weekend and pretty pumped. I didn't think a boat like this was going to come around too often so didn't feel waiting for one with a 150 would have been an option. This Tuffy did everything I wanted in an upgrade being able to store 8'6" rods, being able to fit in my garage, etc. I did a lot of comparing to other boats. Some tin boats were really nice and would have done some of this too but wanted to get into a glass boat to handle bigger rougher water a little better when needed. And was all within, well I stretched it probably just a bit , within my budget. Planning on keeping it long term though.

I'm thinking of upgrading to a 150 to cruise at the mid-range rpm's when gph would be significantly less than WOT with the 115 at a higher speed. And also just for the added power to ski and tube behind with ease.

I haven't had the boat wet yet. It's going to be a long wait for ice to break. So gonna wait to see what she's like once I can get her on the water. Maybe it'll be fine. I also like the idea of low 50 mph speeds vs maybe low 40's with the 115. What can I say, like to go fast.

No worries on hijacking the thread. Was good info to learn about rake and stuff too. I'll probably play around with prop pitch and get a 4 blade prop too. From seeing some prices of used, yet really new 150's, like a year old, it would probably be in the neighborhood of $5-$6k.

[delcecchi]

Thanks for all the replies! And sorry I was MIA for a bit. The boat is a Tuffy Osprey 1760 so she's a little heavier. Just picked her up over the weekend and pretty pumped. I didn't think a boat like this was going to come around too often so didn't feel waiting for one with a 150 would have been an option. This Tuffy did everything I wanted in an upgrade being able to store 8'6" rods, being able to fit in my garage, etc. I did a lot of comparing to other boats. Some tin boats were really nice and would have done some of this too but wanted to get into a glass boat to handle bigger rougher water a little better when needed. And was all within, well I stretched it probably just a bit , within my budget. Planning on keeping it long term though.

I'm thinking of upgrading to a 150 to cruise at the mid-range rpm's when gph would be significantly less than WOT with the 115 at a higher speed. And also just for the added power to ski and tube behind with ease.

I haven't had the boat wet yet. It's going to be a long wait for ice to break. So gonna wait to see what she's like once I can get her on the water. Maybe it'll be fine. I also like the idea of low 50 mph speeds vs maybe low 40's with the 115. What can I say, like to go fast.

No worries on hijacking the thread. Was good info to learn about rake and stuff too. I'll probably play around with prop pitch and get a 4 blade prop too. From seeing some prices of used, yet really new 150's, like a year old, it would probably be in the neighborhood of $5-$6k.

If the boat runs in the low 40's with a 115, it seems unlikely it will run in the low 50's with a 150. Most likely you will get somewhere around 5 to 6 mph more top end, which would get you from the low 40's to the high 40's.

I also doubt that you will see a significant improvement in fuel economy at cruise, unless you want to cruise at a speed that is pushing WOT on the 115.

Perhaps you could find some performance tests of a boat in the same class that has the 115 and the 150 on them.

The manufacturer's sites can be helpful, as can boattest.com, in giving you an idea as to what you would gain. You probably won't find your boat, but you might find a boat that is close enough in size and weight.