Repower Volvo 4.3s

PierPressure · **Joined:** Mon Nov 02, 2015 11:29 am **Posts:** 20

Okay..so I'm not ready to do this yet....maybe never...but I just wanted to get a ballpark feel for what I might be in for.

I have a 2004 Vista 288 with twin 4.3L Volvo GXI (225HP) engines. Engines currently have around 310 hours on them. Top speed is somewhere around 30-35 mph. Would like a little better top speed...and a much better time to plane. So three questions.

1.) If you were going to repower...what engines would you be looking at?
2.) Ballpark cost to get this done
3.) Is there any type of core or trade in value of the old engines?

Thanks in Advance!

Todd

noexcuses · **Posted:** Fri Nov 13, 2015 8:03 am

According to Four Winns specs, your boat should be getting 43mph at WOT and 31 mph at 3500 rpm which are respectable numbers for a cruiser. You might want to investigate your current engine performance before going down the road of a very expensive repower.

Here is a link for troubleshooting WOT.

http://forums.iboats.com/forum/engine-r ... of-low-wot

Since you have Volvo fuel injection, you might want to investigate paint peeling from you fuel pump assembly that will foul your fuel delivery system to include dirty injectors, the screen on your fuel pressure regulator and the screens on your fuel pumps.

viewtopic.php?f=11&t=14561

GI Auz · **Joined:** Wed Dec 24, 2014 9:12 pm **Posts:** 149

With 220+ HP a side you should do better than 30-35 mph.
Download the Four Winns Fast Facts 2004 - this has all the tabulated data for performance per engine.
My 2004 V288 with Merc 4.3 runs close to the FW data.

My actual real-life results this year
3500 RPM - when full with people (4) - 75% fuel - 150L water - smooth water - 25.5mph
3500 RPM - light - above return trip with 50% fuel - 100L water - 27mph
4000 RPM - 31 mph
4800 RPM - 41 mph - tested a few times
Knock off 3 mph in choppy conditions

I would do a full throttle test when light. Your props may be wrong size? But I don't think so - if you did your time out of the hole would be good but you would loose top end speed.

GI Auz · **Joined:** Wed Dec 24, 2014 9:12 pm **Posts:** 149

The new Merc 4.5 is magic.
Power of the 5L - lighter and sip less fuel.
$40k for a pair - full installed price.
Volvo 4.3 would be similar I would think.
You engine are less than 1/2 way through "typical life" of 1000 hrs.
Full re-power is not a great option unless you drive a Porsche 911 GT3.

FYI - I just had a makeover on my 4.3 Mercs. Pulled them out - cleaned them, new starter motors, changed some hoses, bearings in water pumps, sump gasket, full degrease and removed rust - new engine mounts, new transom assembly, scrubbed out engine bay.
The back end of the boat and engine room almost looks new. Good for another 10 years (I hope!)

PierPressure · **Joined:** Mon Nov 02, 2015 11:29 am **Posts:** 20

My issue may must be that I'm inexperienced in driving a boat with twins...with trim....with tabs...etc...

I've been starting with everything trimmed down (engines and tabs).
Throttle up...get on plane....use trim tabs to level out...

That's it.

I assume I'm missing something.

LouC · **Posted:** Fri Nov 13, 2015 4:52 pm

Start with the drive down and tabs down, but first once you get up on plane, trim up a bit till you get no increase in rpms, then use the tabs to trim side to side. Ultimately the tabs help get you on plane but once up they should be retracted and just used to balance out your side to side trim. Most important what is your wide open throttle RPM? It should be between 4600-4800 RPM. If not you may be over propped. May need to drop your pitch.

Surface Interval · **Posted:** Fri Nov 13, 2015 5:09 pm

Having trim tabs full down will help you get on plane, but they also cut speed on plane. Once you are on plane bring the tabs all the way up. On plane, use a tab only to level the boat if one side is low. Then start to play with trimming the outdrives up a little. At slow planning speeds you won't be able to trim up much. The faster you are going the more you will be able to trim the drives up, .....to a point. As you trim the drives up you will notice the RPM and speed come up. At full throttle and maximum speed, trimming up or down from this point will cause a loss of speed. At maximum speed the outdrive will be no more than just a few degrees above being neutral, (the anti-ventilation plate parallel with the hull bottom). As you trim up you should gain speed. If you notice the nose is porpoising up and down you have trimmed up a little too much.

GI Auz · **Joined:** Wed Dec 24, 2014 9:12 pm **Posts:** 149

Here is my technique.
Tabs full down, legs full down. Throttle up - I only use about 80% throttle which seems enough to launch.
As you just get onto the plain go 1 second up on leg trim. (Takes the leg off the stop and smooths things a bit).
Allow to accelerate - rpm rising.
Approaching 3400 throttle back to what feels like a speed stable power setting - but the will is still accelerate to about 3500.
Then:
If I'm doing a normal cruise I'll leave tabs full down and trim the leg up in 1 second increments.
Each increment will see a speed and RPM rise - as this happens nudge throttle back to 3500 each time.
Eventually, one of the increments will cause the props to cavitate - you will hear it - quickly trim the legs back down 1 second before you loose too much speed.
If there is any chop I will cruise in this condition at 25mph @ 3500 rpm.
If it is dead calm I'll go bow up 1 second on trim tabs and see if I go faster - if I do I'll do it again. RPM will rise - nudge back to 3500. Will be a bit faster that before - may be 26 or 27.

www.iFourWinns.com

Repower Volvo 4.3s

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