Winter Bordom!!!

[Burton]

I've just finished my first "Season of the Donzi" I have a 94 "Sweet 16" 4.3 Merc..205HP w/upgraded Vortec Heads and 4BBL.I had a ball this summer. But I need some advise. I could make great use of about another 50 HP.And since I see the boat's spec say it will take it...
HOW DO I GET THERE? Supercharger? Engine Swap?
Can I do it with this engine? After all the experiences by club members, is there a consensus on "Best Bang 4 the Buck" Thanks :cool: :cool: :cool:

[Barry Phillips]

Put a V8 in that puppy, 50 hp is a lot to find in your V6 and will only gain about 1 to 2 mph. A a 350 would do nicely and be cost effective, plenty of parts arround. Your Alfa should handle 250 to 300 hp and this set up will be more relable than super chargeing. My 18 well run 65 to 67 with a 5.7L (350) making 250 hp and a Bravo 1, and more important it's relable. Donzi did not offer a V8 in 94. Now they are offering a 305, so it will fit, but wy bother with a 305 when you can have a 350.

SO-SLO

[Rodger]

I agree with Barry Philips if your going to do the engine swap. Skip the 305 and go bigger. I put a SB 406 in my 16' but they might be too hard to find and I did break my lower gears with that engine. A 350 is fine and can be found easily.

[Gearhead99]

Remember no substitute for cubic inch.

"Bigger is better, except in women"

Go to at least a 350, 383 would be nicer. Same external size too.

[ToonaFish]

"Bigger is better, except in women"
Really? Guess I'll stop shopping for a new set...

Ahem, anyway Burton, everything I've read and seen points to the cost/benefit ratio of improving the 4.3 being zilch. Far better to go to a V8 (don't forget the extra weight will eat a few of those horses) or simply enjoy the quite respectable speeds that you currently posses.

Bunches,

Celene 'you got snow yet? we got ice!'

[mikev]

Im going to have to hop up my 4.3 because a 350 wont fit under the doghouse of my 19' Regazza its to long. i know several gus with s10 pickups that have gotten over 300hp dynoed on a 4.3 without real radical cams im goint to run 10:1 compression GM high performance cam wit 1.6 ratio rockers, bigger valves, port and polish the heads this should get me to 300 hp. imco makes some nice manifolds for the 4.3 too. but if i had the room i would go with a bult 383 probably cost about the same and get 400hp.

[Burton]

Thanks for all the comments so far! If I do the engine swap, what is a resonable investment, and is the 4.3L worth anything?
:cool: :confused: :cool:

[Rootsy]

i have a 350 in my 16... i wouldn't trade it... cept for maybe 383 or 427 cu-inches of sbc and a BRAVO... downfall #1 of having a small block under the hatch... THERE IS NO ROOM TO DO ANYTHING! everything is a pain in the arse... the front of the motor is literally an inch from the back seat. you have to be a contortionist to change oil or do anything below the valvecovers... it is just tooo tight with stock mercruiser exhaust. soooo remote oil filter setups are very NICE. just to get the motor in and out (V8) you have to strip the front of the motor as well as remove the exhaust and spin the motor 90 degrees to get it through the hatch opening... and even then it is a tight fit...

Downfall # 2... as for the extra hundred or two lbs you tack on goin to the sbc... i dont know if it really makes a huge difference, BUT the 16 already has plenty of weight in the arse as it is... so less is better if at all possible... so to balance the swap think aftermarket exhaust, aluminum intakes and possibly cylinder heads (freshwater)...

even then the 16 will be slower than an 18 of equal power... just from the hull hydrodynamics, ride attitude and controlability... the 16 gets very skittish when trimmed at higher speeds but this can be minimized with some prop selection, seat time and weight distribution...

last thing to remember... the 4.3L setup uses a lower gear ratio sterndrive. 350's and 305's pretty much come standard with 1.47 ratio drives, there is the high altitude 1.65 or so ratio also... and i believe the 4.3's come equpped with the 1.8(something):1's... which really is probably too much gear for the torque and you'll end up spinning A LOT of pitch with a modified motor. therefore it is more than just a motor swap...

the good news is... the motor will fit under the hatch just like the 4.3 so you don't have to do any cutting... except for possibly behind the seat for power steering pump pulley clearance...

[Barry Phillips]

I put a remote oil filter on 350 after the first oil change, my rips were score for a week from laying on top of the risers. A Mercruiser remote oil filter kit off the MPI 350 Mag worked nicely. Changeing the oil is now a snap.

SO-SLO

[HyperDonzi]

Recently intrested in the exact same thing you are.... (in a baja, not a donzi :( ) I decided to stay with the 4.3 because of a few reasons. The first is the fact that the motor is in there now. The second is all the under hatch room. Third is the fuel system might need new lines, pump, etc.... The fourth is the gas guzzlers fee. That 4.3 is Lots smaller than that 350 so it dosent need as much gas (you can tell I'm in highschool by the last thing!)

cons: Wont gain as much hp/dollar as V8. A V6 of equal ci will never make as much torque as a V8. Wont have that nice V8 rumble either.

Remember, things that fit in a 350" will fit in the 262 because the 262 is a 350-2 cylinders)
ie-Rods, pistons, carb....

[Verdugo]

Hey Burton I am also looking to upgrade my 4.3 on my 16 ft 1994 Classic. Same senerio and am lookin at the 350 engine with 300hp I have been quated @ we are looking around 4,500 to 5,000

well I just got mine 4 weeks ago and think I will be waiting. Hear in AZ I ca run to the lake anytime but will be waiting to do this type of $$$ especilly when the boat has 125 hrs
I hope this helps you in the right direction

Verdugo

[HyperDonzi]

When thinking of the 350", I was told by a Factory 1 racer to go with a ZZ3 or ZZ4 crate motor with lightening headers. He said he put one in a ZZ3 in 1991 with a 125 shot of N2O and it HAS NOT been torn apart and had approx 50 hours a year on the motor.

[mikev]

you guys that swaped a 4.3 for a 350 how far forward did you have to move your motor mounts or did it bolt right in?

[Burton]

Heh Guys,
Found a reasonably priced 5.7L 250-260 HP with Alpha GenII.
What do you think?
Will it fit?
Thanks :cool: :cool: :cool:

[Rootsy]

it'll fit... center riser manifolds are a must... this is what it'll look like all crammed in there... it isn't difficult to do... just have to take your time, do some planning and don't rush things... being on the small side helps too... wink

http://www.donzi.net/photos/jaroot040.jpg

http://www.donzi.net/photos/jaroot041.jpg

http://www.donzi.net/photos/jaroot042.jpg

http://www.donzi.net/photos/jaroot015.jpg

[Burton]

Jamie,
Thanks for goin to all the trouble with the pictures! Think I'll be okay with a GenII Alpha?
:confused:

[Rootsy]

at 250 or 260 hp... you'll be just fine... get the transom assy for the GEN II also... the GEN II and the earlier alpha / R / MR and 1 drive transom assemblies won't retro without modification...