need to repower my deck boat, is 4.3 engine enough?

[stang32]

i have this boat(96 cobia sportdeck 229) that I just picked up. it has a 4.3 mercruiser, the bottom line is the boat needs a new motor. I am concerned that the v6 motor is not enough power for this boat.i have not driven the boat in proper operating order and
the last thing I want to do is repower the boat only to be unhappy with the results. anyone have one of these boats w/this powerplant? some guidance is much appreciated.the boat has a towing weight of 4000lbs.looking for top speed info & overall handling info
thanks
i do not have ulimited funds & I know Iwill have to change the gears in the drive if I go with a 5.7 v8 but I do not want to do the job 2x

 

[tpenfield]

Re: need to repower my deck boat, is 4.3 engine enough?

I'm thinking a 5.0 V8 would be better than the V6. It might be a good compromise between the 4.3 and the 5.7, and not have to mess with gear ratios, etc.

 

[stang32]

Re: need to repower my deck boat, is 4.3 engine enough?

you still have to change the gears from what I remember. the gears on the v6 to v8 are different

 

[rick3452]

Re: need to repower my deck boat, is 4.3 engine enough?

I have a 24ft deck boat with a 5.0 M/C, 3700 lb boat I would only go with a 5.0 and you will be very happy.

 

[Stamey]

Re: need to repower my deck boat, is 4.3 engine enough?

4.3 has 1.81 gears and 5.0 has 1.5 gears, so a change would be in order there. Don't discount the 4.3 too quickly. They have good power and good fuel mileage. To me, that's why I'm going to stay with a 4.3 in my 24' Rinker Flotilla deck boat. The current engine in mine has only 70# of compression on number 4 cylinder, but I bought it knowing that, and the fact that I would probably have to put an engine in it. I had her out for the first time this weekend, with the weak engine, weighing 3500# before fuel and people, and was very happy with the performance and fuel mileage. Running up an down the lake all weekend, to the tune of about 54 miles, pulling a towable some of the time, I only used about 20 gallons of gas. I'm really happy about that.

My 4.3 is rated at 180hp, from what I can tell about the specs. While I have not verified it yet, I was told by a fellow this weekend, who had a 4.3 in his 19' bow rider, that if you switch to a 4 barrel carb, you get up to 225hp, and if you go fuel injection you get it up to 275hp. If I can get that out of a 4.3, I will be really happy about that. I don't know that I'll go as far as fuel injection though.

Chris

 

[Struc]

Re: need to repower my deck boat, is 4.3 engine enough?

I have a 4.3l in my 20' Sea Ray bowrider. It's the 175hp 2bbl version, and it has PLENTY of power.

If you're worried about it, do a Vortec head swap (1996+), get a new intake manifold and 4bbl carb, and you'll be in the 235hp range. That's V8 territory.

Edit: Just re-read your original post, and see you have a 1996. Ensure the intake manifold has 8 bolts holding it down instead of 12.
8 = Vortec
12 = older non-Vortec

 

[jkust]

Re: need to repower my deck boat, is 4.3 engine enough?

I have a 4.3l in my 20' Sea Ray bowrider. It's the 175hp 2bbl version, and it has PLENTY of power.

If you're worried about it, do a Vortec head swap (1996+), get a new intake manifold and 4bbl carb, and you'll be in the 235hp range. That's V8 territory.

Edit: Just re-read your original post, and see you have a 1996. Ensure the intake manifold has 8 bolts holding it down instead of 12.
8 = Vortec
12 = older non-Vortec

Here's my take and my background, I've got the basic 4.3 liter carb and my boat is 3000lb dry plus 33 gallons of gas and usually 4 people. It does a respectable job considering the 270hp v8 was the optional engine. I wish I had the optional v8. Also, the vortec heads plus the 4bbl carb/intake will not get you near 235hp sadly. You can check the widely available specs for that upgrade on the internet.

 

[Scott Danforth]

Re: need to repower my deck boat, is 4.3 engine enough?

with the 4.3 your drive should be 1.81:1 ratio. the 5.0 was usually a 1.62:1, and the 5.7 was 1.5:1

the 4.3 should do fine in the boat. put it in and go boating. no mater which engine you put in, you will always want more power (until your at the fuel dock)

 

[bnicov]

Re: need to repower my deck boat, is 4.3 engine enough?

A newer style Vortech with a 4bbl carb will run about 210hp, not 225 and up. With a fuel injection setup, about 220hp. Any more than that and someone is blowing smoke up your wazoo unless the engine has been modded. A boat that size, I'd be thinking 5.0 or even a 5.7, reason being, it's better to have more than enough power than just enough power. A few people on the boat + their stuff and it will be heavy and sluggish. Unfortunately, it means changing out the leg as well although you can get some dough for yours. Good luck.

 

[sstone]

Re: need to repower my deck boat, is 4.3 engine enough?

24' sundeck has the 5.0 and I think its a perfect mix of power and fuel mileage. Easily pulls skiers up with an 8 passenger load, but can cruise and pull tubes all day on a half tank of gas. Top end of around 45, a little more with an empty boat, no complaints

 

[HT32BSX115]

Re: need to repower my deck boat, is 4.3 engine enough?

i do not have ulimited funds & I know Iwill have to change the gears in the drive if I go with a 5.7 v8 but I do not want to do the job 2x

You will spend a LOT of money re-powering with a larger V-8 and replacing the drive.


2 identical boats side-by-side will consume approx the same fuel (flow) to go the same medium planing speed when loaded approx the same because both engines exhibit approx the same BSFC (Brake Specific Fuel Consumption) to produce the same power.

The fuel consumption will not increase all that much unless you do a LOT of full power cruising or a LOT of full power starts.

Your "right hand" will control your fuel use.

I would always want to go to a bigger engine. (more is usually better in boats) But a deck boat? it's a floating, planing, portable "DOCK"!! not a racing boat!

Save your money and buy fuel, propane for the barbecue and ice for the cooler!!!!!

 

[stang32]

Re: need to repower my deck boat, is 4.3 engine enough?

well considering the P.O replaced the original motor with a junk yard engine, I cant confirm the year of it.
I have repowered several boats w/larger engines already, I can buy a new drive top end for 500, new & sell my old one for around 4oo.I can sell of my complete 4.3 for a couple hundred as well
if i find the right 5.0 or 5.7 ready to drop in, i will be ahead of the game. i already have an eye on a complete 5.7 tbi engine w/closed coolant system for under a grand, only thing I have to do is put a new crank & bearings in , due to a knock. so after al lis said & done under 2 grand & I am back in business.
if I go with a new 5.0 or 5.7, yeah, big bucks, 5-8 grand easy,
if I go with rebuilding my 4.3, like i said, I have no idea on whay year it is, it probably is not a counter balance engine, it will need crank, bearings, rings, head job & gasket kit so if after all that I still have an underpowered boat, what did I gain?

 

[HT32BSX115]

Re: need to repower my deck boat, is 4.3 engine enough?

That boat probably performed ok with the original (Correct) engine.

i already have an eye on a complete 5.7 tbi engine w/closed coolant system for under a grand

But if it were me, I would do the 5.7L "upgrade".
And if you do a 5.7L engine (with TBI) you won't use a LOT more fuel if you keep your "foot" (hand?) out of it!!

 

[stang32]

Re: need to repower my deck boat, is 4.3 engine enough?

well the 5.7 turned out to be a bust, the efi set up will not work w/my alpha drive since it is an MPI made for a bravo set up .
the engine is real nice,although it needs a new crank(rod knock) I pulled the heads & there is no oil build up, no ledge on the tops of the cylinders so they dont need to be bored out & the bearings I pulled still have not completely worn in. I wonder what happened to cause the rod knock.
anyway, i cant use the efi set up, and i am re-reading this post thinking i might be better off w/a 4.3 vortec. at least i can use the closed coolant system from the 5.7 & sell off the fuel injection system & the long block as well.
so, anymore info on how to get the most out of a 4.3 vortec motor would be appreciated

 

[Tail_Gunner]

Re: need to repower my deck boat, is 4.3 engine enough?

Hmm you didnt miss a thing with a old tbi engine..parts are not avaible and those are old engine's. Cant you just call some junkyard and get a 5.7 out of truck for 1500 or a 1000 they should be a dime a dozen....but 4.3 its not so readily avaible.

 

[stang32]

Re: need to repower my deck boat, is 4.3 engine enough?

well yeah i can get a junk yard motor but as a machine shop owner pointed out to me, there is more than just marine gaskets involved in a marine engine, the cams are different. you try running your truck @ 4400rpms all afternoon & see where that takes you.

the 4.3 vortecs are really popular as well. I have found a rebuilder who has them @ 1495 w/2yr unlimited warrantee & free shipping & pick up of old engine, no core charge. he is located in maine, Marshall's marine.net, so i am leaning toward going that route now, I flip flop from moment to moment, my issue these days is money is very tight & technically I can just sit on this boat job till next year, i have a good running(knock on wood) bowrider that i planned on selling once the deck boat is up & running, so I can use that, I am just looking for a project, rebuilding the 350 would have been fun, since i have not done it in years but the thought of having to replace the top of the drive is causing me hesitation. plus buying a new intake & carb on top of that

my problem is right now, i have more time on my hands than money & as THEY say, "idle hands are the devils workshop"

 

[Struc]

Re: need to repower my deck boat, is 4.3 engine enough?

well yeah i can get a junk yard motor but as a machine shop owner pointed out to me, there is more than just marine gaskets involved in a marine engine, the cams are different. you try running your truck @ 4400rpms all afternoon & see where that takes you.

the 4.3 vortecs are really popular as well. I have found a rebuilder who has them @ 1495 w/2yr unlimited warrantee & free shipping & pick up of old engine, no core charge. he is located in maine, Marshall's marine.net, so i am leaning toward going that route now, I flip flop from moment to moment, my issue these days is money is very tight & technically I can just sit on this boat job till next year, i have a good running(knock on wood) bowrider that i planned on selling once the deck boat is up & running, so I can use that, I am just looking for a project, rebuilding the 350 would have been fun, since i have not done it in years but the thought of having to replace the top of the drive is causing me hesitation. plus buying a new intake & carb on top of that

my problem is right now, i have more time on my hands than money & as THEY say, "idle hands are the devils workshop"

Here is my 4.3l engine build up - it might have some interesting info in it for you.

http://forums.iboats.com/showthread.php?t=520824

Truck cam is fine. The problems start when you get a "hot" automotive cam. On the short block, about the only thing you have to worry about is the core plugs. Make sure to swap them out. Other than that, find a junkyard 1500, Astro Van, etc and start rebuilding. I did the engine rework (without actually rebuilding the motor) for $500'ish, including having to buy and set up a whole new electric fuel pump setup.

I also wouldn't get too hung up on Marine gaskets, depending on if you're running fresh water or salt water. Hard to say with only "NY" in your location field.