Replace Early 4.3l V6 With Newer Gen Vortec Engine

[vultron81]

I have a 1992 Wellcraft Eclipse 196 XL. The boat has a Alpha One Gen II outboard and Mercruiser 4.3l LX 4 barrel that overheated and now two rods are knocking. The older motor has the Thunderbolt IV ignition, roller cam, and fluid motor mounts. I plan to replace the broken motor with a newer 4.3l vortec long block from Rapido Marine. I discussed this with Raul and he mentioned I will need a newer intake manifold, aluminum oil pan, and electric fuel pump. Is there anything else I need that will not bolt on from the older motor? What kind of power increase can I expect from this newer generation 4.3l motor?

 

[180shabah]

Re: Replace Early 4.3l V6 With Newer Gen Vortec Engine

You will also need an oil pressure switch for the fuel pump.

Vortec + good intake manifold (edelbrock performer) + 4bbl carb should give you a solid 210-215hp at the prop. That will be very noticable over the 175hp you have now.

You will also need to look at a new prop after this (unless you are over-propped now).

 

[mylesm260]

Re: Replace Early 4.3l V6 With Newer Gen Vortec Engine

Yes, a new prop will be highly recommended.

This upgrade will not only give you more peak HP, but also give you more torque across your entire RPM range. Those Vortec heads flow much better across the entire band.

Increasing your prop pitch will also help with cruising fuel economy. For me, I used to have to turn 3600-3800 or so to stay at 30 MPH, now I can cruise @ 30 MPH at 2900 rpms.. makes a night and day difference.

When I upgraded from my carbed 160 HP 4.3 to my 220 HP EFI'ed vortec 4.3, I went from a 19P to a 23P prop, and my top speed went from 50MPH to 63MPH (GPS)

And even with the "bigger" prop, my hole shot and plane time is about the same.

 

[vultron81]

Re: Replace Early 4.3l V6 With Newer Gen Vortec Engine

The intake manifold I am getting is a cast iron GM and not the aluminum Edelbrock 2114. I believe it is the same as this one: http://www.michiganmotorz.com/Marin...-+4+Barrel+Vortec+Intake+Manifold+(1996-2008). Any opinions performance wise between the cast iron GM and aluminum Edelbrock manifolds? I will only be using the boat in fresh water lakes so I wouldn't need to worry about salt water corroding the aluminum. I plan to use the stock 4 barrel quadrajet Rochester that came stock with my 4.3 LX.

 

[vultron81]

Re: Replace Early 4.3l V6 With Newer Gen Vortec Engine

I created a new thread for the intake manifold question here: http://forums.iboats.com/showthread.php?p=2117127.