LTZCrew

new here but been doing a fair amount of reading and digging and have learned enough to be dangerous

I have a 210 four wins - stable v hull- 21'7 OAL weight in around 3400lbs, boat it self is about 19.5 with out the swim platform, its powered by a 350/300 mpi mag bravo 3 2.2:1 and 24p props
boat currently tops/ rev limits at 50/51mph with 3 people and 3/4 tank of gas

id like to get to the 65-70 range.

now I know the first guy in is going to say - go big block and I would but I don't have the space, that was my first choice and ive already checked and it will not physically fit in the engine bay with out re doing the interior and more can of worms. so big block is out

ive also seen the average seems to be 1k pre mph give or take it seems.
so is less weight or more power the bigger benefit?

my first choice was to pull, stroke and boost the stock mag make a older school style power house lots of grunt and a 5500 rpm range
but
the iron block and heads leaves a lot of weight in the back of the boat and more added with boost and all the goodies

second choice was a ls based small block, keep the iron block but aluminum heads keep it n/a and use cubes, big cam and lots of revs to get there, now I know dissimilar metals seems to be a thing in the marine industry is this still the case in fresh water boats as this is a fresh water boat only and never has and never will see salt water,

so im just curious about peoples opinions or any advice on direction

Fischan

First thing i noticed is you have a bravo 3, if you are getting a solid 50mph enjoy it for what it does currently in stock form. You will be money and time ahead by purchasing a boat designed and built to handle the speeds you are shooting for.

Tinkerer

Speaking from experience I would suggest a different boat that goes the speed you want and will handle that speed without a handling problem. The amount of $ it will cost to get to your goals would be better spent on a different hull. If you spend the $ you will find that you won't be happy with it after a while. I was NEVER satisfied with the results and every year it was something else. I finally got the boat that I always wanted. And the process is still going on. BUT this will be all that needs to be done with this boat since when what I have planed the boat will be capable of speeds that are insane.

rak rua

Four Winns build pretty nice boats, quality, fit and finish, I can see why you want to keep it. As the others have said, trying to improve significantly on how the factory designed and built it will cost you big $$ and may not work out. Possibly effect resale by limiting your market too.

Put your boat on the market and plan to buy something else that you like. Don't sacrifice your boat, hold on for a decent price because it sounds like a nice boat. If it doesn't sell, just keep enjoying it.

Just my 2 cents worth, losing money on boats is inevitable but try to minimize your losses.

RR.

LTZCrew

i was looking at a new to me boat but after thinking about it, witch was probably a bad idea in the long run, I just couldn't do it,

it seems the smaller boats - under 25 feet sit very low in the water and with the lake I run on, I don't want to run the risk of having issues rough waters and high winds. in the summer evening we can get a good couple hours of nasty winds take pretty much every low boat off the water quickly.

now id love to go 25+ in pretty much every go fast maker out there
but then I run into storage issues as space is limited, the launches we have here make it a hassle for anything with any kind of length when your towing along with being flagged by the cops right away. plus I then get a boat with a past I don't really know.

so that how I got to the more power options, not as efficient as a built to haul ass boat, but comes with issues I can handle, and with knowing just enough about how a marine engine differs from an automotive one I have know just enough to be dangerous

Griff

To add 15-20 mph you need to add roughly 250-300hp and switch to at least a Bravo 1 XZ drive. Then you really should get hydraulic steering.

If you're lucky, you might be able to get it done for 25k to do it right.

Then when you're done and ready to sell in a few years, the boat will be worth less than it was stock with fewer potential buyers.

LTZCrew

well this is depressing.
it seems there is no options for a small boat with a small block and the only way to go fast is to getting a bigger boat with a big block

I don't plan on selling the boat for a very long time. waited for ever for it and love it - most of it.
if I was to sell it ever, the mag would go back in it and the new power plant would find a home a new boat

i don't expect it to be cost effective, in it more for the fun and being able to tangle with the bigger boats haha

i kinda expected the 300 more horses would be needed, but what about dropping weight? i know a lighter object will do more with less. any idea on what kinda weight needs to be shed to see any gains? 100lbs per mph?
the drive would be the next thing,
it seems most go fast boats, from the digging and reviews ive seen with stock ish power plants, run a 1.5:1 with a 'shallower prop' 22-24p. is it more effective to spin a less pitch prop faster then it is to spin a prop with more pitch slower? even typing this looks like a dumb question haha

SB

iTrader: (1)

I justed posted a new best speed of a 20ft boat I work on. 72.8mph. And that was with the same prop (21" labbed cleaver) that worked best on it with a stock 260hp 5.7mag at 54mph or so. It is ready for a larger prop now though, as it spun 6200rpm on this 72.8mph run. BTW: It still has the 260hp shortblock. And yes, years of tweaking, this and that has been done. This is not a Bravo boat though. It ran mid to high 60's with stock Alpha at up to 5600rpm. The additional jump was the addition of an Alpha SS. So, yeh, the prop stayed perfect for the boat unti this last mod.

Too many people make a big mistake of selling/trading their 'best prop' before they trial there boat with a higher hp engine. Worst case scenario of trial running with last 'best prop' is that it doesn't work, but this info on how it ran will be a boat load of info (pun intended) for a prop guy to help dial you in.

Only a few times I talk people out of modding ere boat, and it is usually someone that has a way to big boat for stock single engine. Say, a mid 30-40mph boat. There are some boats out there that will be lackluster performance wise even if they swap a stock small block for a mild big block. They exist !

If you are going low 50's now, I think 60 is a reasonable goal. Anything over that is a cherry on top. And sometimes you'll get that cherry.

Too Stroked

Griff hit the nail right on the head. In fact if you do some searching around this site, you'll find lots of people who have asked almost the exact same question because the were in your exact position. The sad truth is that your Four Winns was never designed or built to take the kind of pounding going as fast as you'd like will give it. (And trust me, I speak from over 50 years of experience on the water.) Sure, you can drop in a motor that will give you the power you need to go that fast. Then you can slap on a new drive that will handle the extra power you just installed. Then you can install new hydraulic steering to handle both the speed and steering torque from the new power.

But then when you hammer the throttle in any kind of rough water, you'll start to feel the boat falling apart around you. (This assumes that you can actually open her up without discovering all sorts of evil handling traits that pushing a hull past its design limits will bring out.) Sure, you could have a professional add reinforcement to the hull, deck, stringers, etc. in an attempt to hold everything together, but that would add weight - which would scrub off speed. Back to step #1 again. And as Griff said, if you finally come to your senses and try to sell the boat, it won't be worth anything near what it would have been in the un-modified condition.

Trust me, if you really like the boat, enjoy her as she is. If you really want to go a lot faster, sell her and buy a boat designed and built to go fast. If you really dig into the design and construction details, you'll find that there's a reason a good high performance boat costs so much, but handles so well. They're a completely different animal than what you now have.

Please don't do what an idiot near me did a few years back. He added a Nitrous kit to an 18' Baretta. When he hit the bottle, he lost control, hit a cement pier completely separating the hull and deck. Oh yea, and he's dead now.

SB

iTrader: (1)

Oh, Donzi Matt has a stout low hr carbed 385 (AFR heads and the like) that came out of a 80mph 20ft boat with an Alpha SS. Yours won't go this fast, but the motor obviously has some steam !