3.0L to 5.0 or 5.7 swap on pontoon boat???

[ski cat jr]

Hi,

I am wondering if I could gain a little more power and atleast 10mph by pulling out my 3.0 and bolt in a 5.0L MPI. I have a Alpha 1 outdrive. Has anyone ever attempted this, is it even possible? Thoughts??

Thank you in advance!

 

[Bondo]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Hi,

I am wondering if I could gain a little more power and atleast 10mph by pulling out my 3.0 and bolt in a 5.0L MPI. I have a Alpha 1 outdrive. Has anyone ever attempted this, is it even possible? Thoughts??

Thank you in advance!

Ayuh,... It's possible, but ya need everything from the pulleys to the prop to do it right...

 

[Silly Seville]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Don't forget a change of gearing (drive ratio) must be done to better use that V-8 power!

 

[John_S]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Nothing like making a plowing hull try to plane. Lots of work, added weight, and potential handling issues on a pontoon, and maybe not the speed increase you want. But, could still be an interesting project.

 

[ski cat jr]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

So, how would I figure out what the gearing ratio is in the boat now and what I should have coupled to a V8??

 

[Don S]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

A 3.0L engine uses a 1.98:1, while a 5.7 uses a 1.50:1 ratio

 

[John_S]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

A 3.0L engine uses a 1.98:1, while a 5.7 uses a 1.50:1 ratio

Those are standard ratios for planing hulls, but would bet for a pontoon, going to want a higher numeric ratio. I'd try to find out from a pontoon mfg what ratio they run with a 5.7L. Outside of a 3.0L, have not seen an I/O on a pontoon.

 

[Lodgepole]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

I had a pontoon a while back and went to a deck boat with a 3.0. I don't think you will get the desired results with the V8 since the pontoon is just designed to plow. With that kind of power, if you hit a wave, the bow may just submarine. Some of the newer ones with the planing finns realy get on top and go. I would not consider a pontoon without the finns unless I just wanted to put around.

 

[Bamaman1]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

There are some pontoons with larger V8's, however they're usually tritoons with lifting strakes. And, they're late model, expensive units.

If you want more speed, it might be best to sell your present unit, and buy another that'll perform better. High speed toons comes from having three toons, the strakes and a having the bottom crossmembers covered with aluminum sheeting. Then, you can trim the front end up and out of the water if you have adequate horsepower.

We're now seeing 250-350 hp pontoons regularly, and they can approach 50 mph with a load. That's fast.

 

[Don S]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

I'm going to move this over to the Pontoon forum. If you decide you are going to go through with the change over and need specific info for replacing, no problem and the Mercruiser forum is the best place for your question. Since pontoons aree kind of in a boat class of their own in how things work, the Pontoon forum may be the best place for this thread at this point.

 

[The Rooster]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Hey "ski cat", as "bamaman1' stated, without a third tube w/ lifting strakes and full underskinning, it's doubtful you will get the results you are after. Of course, there is also the possible legal issues of overpowering the barge and insurance if an incident happens. Can you be more specific about brand, year, and length of your barge ?

 

[5150abf]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Find out what this cost before you go any farther and that will probably make up your mind.

I checked on an engine from work(Bennington) for a freind, a 5.7, and just for the engine it was in the 26K range and you would need a different drive too so add another 3K plus the install so I think it would be quite alot cheaper to just find a boat with the engine you want already in it.

Most I/O pods are the same they just use different engine mounts, which are normally welded in so changing them would be a real bear too so you could technically do it but it wouldn't be cost effective and you wouldn't know how the boat will do until it is done.

 

[Scott Danforth]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

isnt the purpose of a pontoon to go slow loaded with coolers, babes, and having the best stereo you can afford?

 

[Blank-N-Ship]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

We're now seeing 250-350 hp pontoons regularly, and they can approach 50 mph with a load. That's fast.

"Approach 50mph" in a 250HP outboard tritoon? We've broken the 50 barrier a while ago and now we have to put in the 75mph-top speedometer on some of them.

 

[ski cat jr]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Okay, so I think I am ruling this swap idea out. I just hate the idea of a deck boat as I Live in Az & the lake around here have more of a decomposed granite beaches and it is very hard on fiberglass. We like the pontoon set up for durability as we go boat camping everyother wkend in the summer and I am being a wuss and dont want to carry all our camping gear thru the water to set up camp if we traded for a deck boat. Thanks for all your help

 

[Scott Danforth]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

I just hate the idea of a deck boat as I Live in Az & the lake around here have more of a decomposed granite beaches and it is very hard on fiberglass.

thats why they sell keel guards

 

[Bamaman1]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

Blank-n-Ship:

I saw your local LeisureCraft manufacturer's pictures of their tritoon running 53 mph on Lake Tansi with a big Suzuki engine. Don't you know the local retirees were glad to see that thing barreling down that little lake. They're having to put bass boat speedometers on them when the horsepower goes up to 250-300. That's incredible performance.

Unfortunately, such speed costs serious $. But when a pontoon will easily last 30 years if kept out of the weather--they're a great value for the long run. Re-engining a pontoon is just so much easier when it's an outboard.

I/O's just take too much maintenance after the first 5 years, and rear weight is a very strong factor in a pontoon boat. I don't know how they do maintenance on I/O engines on a very skinny toon.

 

[hellion68]

Re: 3.0L to 5.0 or 5.7 swap on pontoon boat???

We are running a 4.3l alpha 1 1.62 ratio w/ a 15p stainless offshore prop, at 4100 rpms it goes 34 on gps with 4 adults and 2 kids. 24' Crestliner already came underskinned...