Volvo penta or Mercruiser repowering?

andyc

andyc

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I am Repowering a 1.5 ton boat single engined 5.8 efi volvo penta engine with Duo props.
I want to repower with either a 5.7GXI Volvo or a similar Mercruiser.

What is cheepest .
What is best for reliability?
What is best for fuel economy?

Seeing as the boat is very light, do you think I should save 170 kg and go for say a smaller and lighter volvo 3.0gxi 130 hp petrol or would I loose alot of top speed?
 
There could be all sorts of discussion re reliability, economy etc but for me Volvo fitted boats command a better resale price. My observation comes from my own boat which was fitted with both options. The Mercruisers seem to sit around a lot longer before a sale.
 
Had Mercruisers in my last one and Volvo's in this. dont think there is much to choose in the engine department, most are GM blocks anyway whichever you go for.

For what it is worth I heard that Mercruisers are the best engines, Volvo has the best drives.

Would not think resale is that much different on Petrols, may be different if you were going diesel

Ian
 
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There could be all sorts of discussion re reliability, economy etc but for me Volvo fitted boats command a better resale price. My observation comes from my own boat which was fitted with both options. The Mercruisers seem to sit around a lot longer before a sale.

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That may be the case with diesels, but with petrols there is really nothing in it. Both use the same blocks and many of the bolt on bits. It's really only the paint that's different. /forums/images/graemlins/grin.gif
 
Do NOT replace a 300 (ish) HP engine with a 130!!!

Yes it will be a bit lighter, and yes it will be a bit more economical, but you will HATE it!

I used to have a 28' boat with a 5.7V8 in it - my last boat was a 22' boat with a 145hp 4cyl in it and the difference is huge.

No oomph for getting on the plane, towing water toys etc etc....

Now having said that, if you don't want planing speeds often, and don't want to tow toys etc then it might be ok, but I doubt it!

I think the advice above is sound, go for a 4.3 if you must downsize, but try and get one of the fuel injected ones if you can, more power and less weight.

If the boat is over 21' I would reccomend duoprop style drives rather than single prop.
 
[ QUOTE ]
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There could be all sorts of discussion re reliability, economy etc but for me Volvo fitted boats command a better resale price. My observation comes from my own boat which was fitted with both options. The Mercruisers seem to sit around a lot longer before a sale.

[/ QUOTE ]

That may be the case with diesels, but with petrols there is really nothing in it. Both use the same blocks and many of the bolt on bits. It's really only the paint that's different. /forums/images/graemlins/grin.gif

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Not convinced!

Volvo and Merc outdrives are substantially different. Also cooling systems, electrical / engine management systems etc.

Just listen to the "grrrraaaaunnnch clunk" you get from a Merc Alpha engaging gear compared to the smooth(ish) clunk from the cone clutches on a Volvo...

dv.
 
All barr my first boat which was omc, they've all been mercs and i've had no problems.
As mentioned, the blocks are pretty much the same. I did hear once that volvos were harder and more expensive to work on but i cant back that up.
If you dont mind losing a little speed but want to increase fuel efficiency, then go for a 4.3 mpi engine. It will be cheaper to buy(new) and lighter. I once had a 4.3 efi in a bayliner 2052 which was well suited. Dont buy a carb engine.
 
Lot of good points here, I'd recommend a Merc V6 MPI 230hp with a Bravo 1 drive, then you get lowest weight for installed hp and smooth shifting with the Bravo drive, and better economy than a carb version.
 
my first real boat was 21ft 1600kg with Merc 4.3V6, 200HP max speed was 37kn and she had enough Oomph for toy's
the next one was 23ft 2200kg with merc 4.3Vp MPI, 210HP,
max speed was 32kn, Oomph was just on the edge of being acceptable. But still nice and economic cruising...


so depending on the weight of the boat make sure you have enough power.
I would never go below 4.3L for 1500kg, and alway's electronic Carb.

I ve alway's been afraid of these 5.7l petrol monsters, (fuel consumption) So then I would choose Diesel, but as there are so many GM bloks around, and diesel has also become expensive it must be OK to have one of them.

When petrol I would choose Merc, just for availability of spare parts and maintenance, so For Diesel I choose VP.
Agree about the unpleasant Clunk of the Merc alfa drive, but mine have never failed, and have you ever thought about the zillion units that are spread around the globe ? they must be OK IMHO

oh yeah and for the weight, make sure you have real figures, weigh the boat, or make a list of all extra bits and pieces, battery's, pumps, ankers, electronics, liquids, spare parts, fenders, etc... none of this is included in the published dryweight, you will be surpriced /forums/images/graemlins/shocked.gif
 
Some very good points Bart, especially the one about the 'brochure' weight of the boat.

Being re-sale obsessed, only because I understand power-boat, human nature, I would lean towards keeping the boat as original as possible.
The boat was clearly built for plenty of go, and those in the market for that brand, will expect just that.
You don't need to use the power, but its nice to know its there.

I don't agree the 5.7 M.P.I. engine is a monster in a small boat, normal cruise revs (3000 to 3400) should consume around 25 litres per hour, in a 1.5 tonne boat.

Merc. and VP have both come a long way with their petrol products. The OP should be able to drive a pretty good deal at the moment.
 
Well, Brought a nearly new 5.7gxi efi engine complete bobtail but with damaged block.Im going to get a new short block and swap everything over.
Fun part will be trying to mate it to my Volvo DPS drive that had a ford based Volvo penta V8, as the new one is GM based and came from a boat with an sx drive, so I think I may have to change bell housing assembly and do a little bit of modification to make it fit my drive.

Any one ever done this ?
 
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