4.3L V6 Questions

[Kerr713]

I am in the process of purchasing a 18' NW Jet boat with the 4.3L V6 Vortec with Holley 4bbl and have a couple of questions. Have tested the boat, handles well, gets up and moves and cruises at 28mph on 3600rpm but a little more power never hurts...and I can never leave anthing as is....

1) The EFI versions of the 4.3 Vortec are rated at 225HP vs. the 190hp rating on the engine I am purchasing. Is the only difference the fuel injection, or are there other factors in the HP difference?

2) A Converion to EFI woudl be rather expensive and a little tricky, but very doable. Are the enough power upgrades to effeciently (GPH) get the 4bbl to to 210- 230HP range?

3) What kind of fuel consumption should I see, I am guesing around 6-7 gph?

4) What manuals, sources are out there for information regarding maintenance, rebuilds, upgrades etc...?

Thanks in advance
Aryn

 

[mkast]

Re: 4.3L V6 Questions

Questions are cheaper than parts.
Having said that, maybe you might think about taking the purchase price $xxxx plus the cost of upgrades $xxxx and look for a boat that is more to your liking.

 

[paultjohnson]

Re: 4.3L V6 Questions

That sounds slow to me, I dont know how much different a jet is but my old 18' 86 pre vortec 4.3 2 bbl 185 HP Runs about 40 mph or so at 3600 rpm if I remember correctly. From about 20 mph to low 30s i run pretty much matched rpm to mph. 2600rpm=26mph maxes at 50 or a bit above at 4400 rpm. Not really an answer to your post ,, just me talkn...

 

[kellmike626]

Re: 4.3L V6 Questions

Why spend the money on upgrading the 4.3 to efi, when you could find a boat with an i/o already EFI equipped? If you want more power and speed, go for a 4.3 EFI or MPI, or just go for a boat with a 350 V8 motor.
Seems more reasonable and way less expensive.

 

[thumpar]

Re: 4.3L V6 Questions

Don't buy a boat that you plan to upgrade because it is not what you want. Unless you get it free or dirt cheap it will cost you more in the end.

 

[Silvertip]

Re: 4.3L V6 Questions

You might consider this: The 4.3 spins the pump at whatever WOT is with existing engine. In other words, the pump is sized to the engine. Since making more HP does not necessarily increase RPM the impeller still spins the same RPM therefore you've done little to increase speed but you would likely increase hole shot and mid range performance. So unless some changes are done to the pump as well, you are spendiing money on only half the problem.

 

[Tail_Gunner]

Re: 4.3L V6 Questions

Efi will not give you any gains by itself. I ve found it to be a simple system that allows you to precisly control fuel flow rates and timing advances... a bit over simplified but that is what it is. (you can control fuel flow rates every 200 rpm...and that again requires specail equipment to get your afr right)

You can benefit from it in terms of turn key starting along with slighty better fuel economy and a small increase in power..perhaps.

A 4.3 will benefit from revising the cam profiles and valve train componets costing about 1600-1800 if your a do it yourself person. Horsepower gains could range from 250 to 280.... Not a lot of hp gaing for a jet boat

But you can pick up a crate 350 doing about 350-400 for 2800...another 1000 to marinize it...Marine hotrodding is not cheap.