What Gives a 4.3LX 25 More HP? Or Go 5.0?

G

GJarrett

Member
Oct 3, 2006
649
Tampa, FL
Boat Info
'02 260 Sundancer
Engines
6.2 MPI
I think I've grenaded my current engine and am looking to repower. It would be MUCH cheaper for me to simply buy a longblock or shortblock and reuse as much of my original parts as possible - intake manifold w/4bbl carb, risers and elbows, etc - than to buy an entire new engine.

Claimed HP numbers go all over the place but as best as I have been able to research old archives and stuff, the standard 4.3 put out about 175~180 hp and the 4.3LX was rated at 205hp or so. The only visible difference I know is the obvious fact that the LX had a 4bbl carb and the std 4.3 was 2bbl. Did just the carb account for the extra hp or were there also differences in valves/cams etc in the head and/or other differences in the two engines?

I've been Googling some links and found some short blocks and some roller-cammed longblocks rated at 190hp. My boat is underpowered as it is (was) and I don't want to buy just a block whlie reusing my intake/carb if I lose any more hp than it previously had. Obviously, if I can just get by with that and keep my 205hp or so, I'd prefer to go that much cheaper route. If there's more difference than just the carbs I need to know; that way I can have the info needed to judge whether a roller-cammed 190hp longblock will provide at least 205hp with a 4bbl on it, or if a shortblock with my original heads (rebuilt of course) will produce that same hp, etc.

If not then I'm looking at an entire new powerplant and may just go to a 5.0 but for the thousands of extra dollars difference between blocks and whole engines I need a little help from your knowledge and experience to enable me to make an intelligent call on what options I have available.

Thanks!
 
Gerald,
You have a 1993 power package. That says volumes...
When I had to replace the engine in 1994, in my 1980 Sea Ray, the price differential for complete power package versus only the engine was about $1000. At that time, to purchase an Alpha outdrive alone was almost $2000. It was a no brainer. Everything new, and no second thoughts.
Unfortunately, not having a crystal ball to see the future, we sold the boat only one year after re-powering her.
No regrets, as the new owner has really enjoyed, and we got more than if it hadn't been re-powered...
Only you can decide....Best wishes.
 
I really want to, but:

4.3 longblock = $2,295
5.0 MPI engine = $5,995

I'm struggling through a rather expensive wish vs. budget decision with this. :smt017
 
Slow South Carolina Boy. :smt021 :smt043


Never said the 5.0 wouldn't be a expensive move up. The long block only costs you $12.08 per horse power while the 5.0 will cost you $23.06 per horse power. But what can you put on performance, and long term satisfaction as a cost?

Good luck with your decision. As I understand the argument, the wallet usually wins. :smt101
 
Dumb question so be nice guys.

If you don't go back with the same engine are you not going to have to change the whole system IE: outdrive, shifter, mounts, wiring/gauges, etc. The cost would not just be the more powerful engine, but the whole package would go up????? :huh:
 
No such thing as a dumb question.

I don't think it will be a big thing to go up in size as long as I stay with the carbed setup. As I understand it the 4.3 I have is simply a 6cyl version of the 5.0/5.7 V8; ie, it's the same engine with the front two cylinders removed. I'm also under the impression that the 5.0 and 5.7 are basically the same engine except the 5.7 has a larger bore. Take 5.7, divide by 8 cylinders, then multiply by 6 and you get a 6cyl 4.3. And both the 5.0 and 5.7 have models designed to mate to the same Alpha drive I already have.

So in theory I should be able to simply drop a V8 in and go; I might have to adjust/move the front motor mounts (?) but that would be it. I don't know enough yet to know if upgrading to an MPI setup would be that easy though; I'd think that alternate wiring harnesses, gauges, etc might be required so that's why I'm only looking at staying with a simple Thunderbolt ignition carb setup.

If I'm wrong I'd appreciate someone here telling me soon before I decide to buy a 5.0 :smt001 but I'm pretty certain I'm right and it should be an easy engine swap if I go that route.
 
I'm not an expert on repowering, but you might want to check the gear ratio on your Alpha first. I believe 5.0/5.7 normally has 1.50 gear while the old 4.3s have 1.84 gear?
 
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