Looking at a boat with Volvo power

[NHGuy]

I'm going to check out a boat with a Volvo Penta setup It has a 5.7 dual prop drive. Question, does the same drive go on the 8.1?

 

[BRICH1260]

Volvo`s dual prop drive can be found on both motors. However, there are different drive gear ratios for each engine.

 

[NHGuy]

Reason I asked is the boat would be far better off with a big block. 5700 lbs. Can a swap be done? Does a certain type of big block plug and play?

 

[tpenfield]

@NHGuy . . . where you been? What are you buying? It would be best to get a boat with the proper engine setup rather than buy something just to swap the engine.

Winnipesaukee? Lots and lots of boats there.

 

[Scott Danforth]

gear ratio is different between an SBC and BBC. if going BBC, I would pick a 8.2/502 vs the 8.1/396 just because the 8.1 production stopped in 2008 by GM (volvo had inventory and kept offering until 2011)

agree with Ted here, buy the boat you want/need vs forcing something

 

[NHGuy]

Boat is kinda special to me 01 Chris Craft Constellation but the low speed is not for me. I have been enjoying my little Formula F223LS. It's pretty dialed at this point. But I can never leave things alone.
I put on an AFR gauge and vacuum gauge to really get it maxed and with the added rpm, blew my head gaskets. So I had it decked which is a blessing because now I can use an MLS head gasket and still have .040 quench. I had been warned by the guys at hotrodders.com that the thin gasket was trouble. And of course they were right.
I am getting to the point that a cabin and a marina slip may be next! So I want a good boat. There is a lesser brand 26 footer with a recent 454 nearby too. And that one has had it's vinyl, canvas and exterior redone. I forget, think it's a Caravelle or such.
I really like quality stuff and I'm willing to work with it.
If I got the Constellation I'd be adding a supercharger, but of course being a Volvo, there are no kits. So I miught have to do my own efi with megasquirt or one of the efi outfits.

I have always like Chris Craft classic stuff. This one has a good price and nice interior. I'm going to probably see it this weekend.

 

[Tail_Gunner]

I'm with Mr Danforth on this topic, the 8
1 would not be my first choice. Actually a lot has changed in the past ten yrs with big blocks, their is a guy named Vortec Pro, getting a very loyal following due solely his success with big blocks. What he did with peanut port heads was eye popping. I'd do some snooping around in regards to this guy. Below is a link, note it's not slick or eye popping, he does not need that. It's all referrals. The guy can build reliable high torque engines at low rpm levels.

VortecPro - Racing & Machine - Homepage

 

[Scott Danforth]

Reylar is the 8.1 source regardless if MC or VP

However a NA 540 or 572 (stroked 502) would be a better all-round motor than one with a huffer. And about 3k cheaper

Megasquirt is one sure-fired way to grenade a boat motor. Remember, you have to run a boat motor rich, not at stoich

 

[NHGuy]

Appreciate the input. I really do enjoy working out all the ifs and buts.
Main reason I would even think about power adder is that the engine would not need to come out. The prochargers for Mercruiser can run as much boost as I'd dare anyway without pulling the engine for ring filing. And some people have done it. I would use conservative power. And I am fully aware of boost referenced fueling and timing retard. There are some nicely integrated air to water intercoolers to help control detonation, and there is software nowadays that listens for knock.

 

[QBhoy]

Depends

Reason I asked is the boat would be far better off with a big block. 5700 lbs. Can a swap be done? Does a certain type of big block plug and play?

my thinking if it helps. I think it depends on what 5.7 it is. Some of the modern 5.7s ain’t lacking power at all. If she is a 5.7 gxi VP for example…you’re talking 320hp and punching over 5000 rpm. Compared to not much older big blocks that struggle to equal that Hp and won’t see 4600 rpm…not to mention the quite serious extra weight they carry. Pound for pound…these later GM 350’s do pretty well. I’ll admit that an 8.1 or 8.2 is a lovely thing and would be more powerful for sure…but…maybe don’t dismiss or underestimate a good modern 350 mpi or gxi for what they can do. So good on fuel, much lighter and just good all around, I think.

 

[Kosmofreeze]

An old thread but one I find interesting - I've got an '01 CC Constellation 26 with 5.7 GXi. It'll do 40+ mph on flat water sucking down 17+ gal/hr. How fast do you need to go?