Comments needed about a 5.7l or 8.1 Volvo engine

[Seevee]

I'm comparing two engines installed in Formula 31PC boats, one with the Volve 5.7 320hp engine and one with the Volve 8.1 8.1 osi bf engine (not sure of the HP). The 5.7 was a standard option and believe the 8.1 was a special option. Also, the 8.1 is equipped with brand new Volvo Ocean drives, a huge plus.

Can anyone comment about the 8.1.... issues, performance, reliability over the 5.7?

Seevee

 

[Bondo]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Ayuh,... The 5.7l is the SBC, 'n the 8.1l, 'n the 7.4l are BBCs....

Ya can't go wrong with Any of 'em...

 

[Don S]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Your title is a little confusing asking about a 7.4 or 8.1, then in your post it's about a 5.7 or 8.1
As Bondo stated the 5.7 is a small block, the 7.4 was replaced by the 8.1 back in the late 90's. The 8.1 is a good engine, no problems there. The problem is the sterndrive. If it has the XDP drive, run away. Only used for a few years and was a total failure. Couldn't keep bellows on them, and the aluminum drive under that composite exterior would corrode away. That mistake cost Volvo a bundle, and you don't want anything to do with them.

 

[tpenfield]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

The Formula 31PC needs Big Block engines . . . While the 5.7's have the overall horsepower rating in a similar range as the 7.4L engines of old, I do not think the low end characteristics will be as good as the BBC engines, either 7.4 or 8.1

What year is the 31PC ???

 

[Seevee]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

This is an 05 Formula 13PC.

Yes, my mistake on the thread title.... I'm comparing the 5.7 with the 8.1.

FWIW, this is the only 31 I've seen with big block engines, does anyone know if that's unusual?

Is there any additional expenses with the big block that the 5.7 doesn't have?

Also, the 8.1 does not have fresh water cooling, but a Salt Away system. Is that the same as Neutra Salt? The 5.7 has fresh water cooling. I really want FWC unless someone convinces me that it's not worth it. I'd guess about $2500 to install on both engines.

Other thoughts? Thx

Seevee

 

[HT32BSX115]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

This is an 05 Formula 13PC.

Yes, my mistake on the thread title.... I'm comparing the 5.7 with the 8.1.

FWIW, this is the only 31 I've seen with big block engines, does anyone know if that's unusual?

Is there any additional expenses with the big block that the 5.7 doesn't have?

Also, the 8.1 does not have fresh water cooling, but a Salt Away system. Is that the same as Neutra Salt? The 5.7 has fresh water cooling. I really want FWC unless someone convinces me that it's not worth it. I'd guess about $2500 to install on both engines.

Other thoughts? Thx

Seevee

Howdy,

I wouldn't buy a used salt water boat that DIDN'T have closed cooling unless it was nearly brand new. (so I could install it myself!)

Don't even consider the 5.7L powered Formula unless and until you drive IT or one equipped just like it.

There is NO substitution for cu-inches! (8.1l engine fuel consumption won't be all that much more for medium speed cruising)

If it has the XDP drive, run away. Only used for a few years and was a total failure. Couldn't keep bellows on them, and the aluminum drive under that composite exterior would corrode away. That mistake cost Volvo a bundle, and you don't want anything to do with them.

TAKE HEED ON THIS! (unless the seller reduces the price accordingly or replaces the drives (which probably won't happen)

 

[QC]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

There is NO substitution for cu-inches!

I would argue that the DuoProp helps a little with this. If top speed is not the most important thing, then I believe the 5.7s are a great option. If top speed is your bag, 8.1s. Agree on the used saltwater boat and closed cooling though.

 

[Seevee]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

First, the XDP are NOT in the picture, it has BRAND NEW Ocean drives.

Second, speed is important, but not an absolute necessity. I'm a fan of bigger engines.

Third, I should have clarified things a bit..... I wanted to compare the two Volvo engines, but if I didn't buy the 8.1 Volvo powered one, I'd probably buy a 6.2 merc one, that is FWC. Similar hours. The 8.1 has a Saltaway system, not FWC.

I basically wanted to see comments on the 8.1.

 

[QC]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

I have a 6.2 and love it, but the 5.7 320 Volvos are the same horsepower rating. Anyone that believes they will not deliver similar top speeds as the 6.2s must believe that Volvo lies on their spec sheets. I don't think they do, so I believe they will perform similarly, especially with DuoProp drives. The 6.2s may have a slight advantage with hole shot (low end torque).

 

[tpenfield]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

This is an 05 Formula 13PC.

Yes, my mistake on the thread title.... I'm comparing the 5.7 with the 8.1.

FWIW, this is the only 31 I've seen with big block engines, does anyone know if that's unusual?

Is there any additional expenses with the big block that the 5.7 doesn't have?

Also, the 8.1 does not have fresh water cooling, but a Salt Away system. Is that the same as Neutra Salt? The 5.7 has fresh water cooling. I really want FWC unless someone convinces me that it's not worth it. I'd guess about $2500 to install on both engines.

Other thoughts? Thx

Seevee

I looked at an older 31PC and it had the twin 7.4L engines. You could possibly add closed cooling to the big block engines. You might want to sea trial the 5.7 boat to see if it does it for you (or not)

 

[GilligansIsland]

Re: Comments needed about a 7.4 or 8.1 Volvo engine

Re: Comments needed about a 7.4 or 8.1 Volvo engine

This may be helpful or not...

I had an 86 Contessa Sunbridge witht the Volvo 260A (SBC) with a SP and then upgraded to a DP... nearly a 30% increase all around.

Now I have an 85 Contessa Command Bridge (Same hull, basically same weight) with the Volvo 7.1 (BBC) with the DP and there is NOOO comparison. The big block at ANY speed just sounds relaxed while the SBC always sounded like it was working.

MPG are the same between the two, in my cases. The BBC will cost you more in parts down the road so that may be a consideration and if you are in salt water, FWC is the only way to go IMHO.



...best of luck.

 

[Seevee]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

Thanks for all the comments, folks, really helps.

Just found out that the 8.1 engine came FWC from the factory, verified by Formula, so that puts it in a strong light.

One of my mechanic friends told me to seriously stay away from Volvo, because parts are so expensive and they have corrosion issues... and the Merc 6.1 is bulletproof, as are the BIII drives. Not sure I totally believe him that the Volvo is that bad. I have no issue with either, however, in my part of the world there sure are a lot more Merc mechanics... but enough Volvo mech to make it work. And while Mercs are pretty good, I've had some issues with them, too. Comments?

 

[GilligansIsland]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

I've never heard of any Corrosion issues with Volvo, but I have heard of them with Bravo lll. Volvo parts are more expensive, that's true.

I think, unless you have an allegiance to a particular make, then you need to decide based on availability of good mechanics, used parts in the area, your willingness to learn how to service the drive (or not). I think they are both fine products and Holy wars can be had over which is better. The question really is, which one is better for you and your situation.

I've only been in boating for 7 years and have only owned a Volvo. I am clearly in Merc country and finding one mechanic who really knows Volvo is difficult to impossible... never mind friends who might be able to help. Had I realized this before I purchased, I would have avoided Volvo. Now, however, that I have become "self certified" in most of the workings of the drive and do all the work myself, I would not buy a Merc. But, only because I know the Volvo so well.

...hope this helps

 

[HT32BSX115]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

I've never heard of any Corrosion issues with Volvo, but I have heard of them with Bravo lll. Volvo parts are more expensive, that's true.

The engines are literally "the same". There is a Volvo drive (the XDP that Don mentioned) that has had MANY problems. You only have to google it and you'll see a LOT of people out that there that had the problems (including severe corrosion).....If that's NOT an XDP drive, I don't think you have much to worry about.....

Many of the Bravo III corrosion problems were related to the electronic corrosion prevention system (Mercathode) not being set up correctly (or at all).
Not being set up correctly could corrode the drive faster than with it disconnected!

Any drive with as much exposed dissimilar metals (SS Bravo III props) MUST be set up to prevent corrosion by following Merc procedure to the letter.

Otherwise, park it in the garage! (I wouldn't want to park ANY boat in salt or brackish water for an extended length of time)

The biggest adantage for getting a Merc might be the availability of parts and/or service. For every Volvo sold, Merc sells 10 (that's an exaggeration but you get the idea)

 

[GilligansIsland]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

I was referring to corrosionn issues in General with the Volvo. I've heard about that nightmare drive and its corrosion issues.

I think considering resale value should be considered as well.

 

[MarkSee]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

For every Volvo sold, Merc sells 10 (that's an exaggeration but you get the idea)

Not an exaggeration here in SoCal as mentioned in other threads. I drive around the lot my boat is storage and I see 1 Volvo and many Mercs.
Same at the ocean boat ramps.

I think considering resale value should be considered as well.

That's a good point as I just mentioned above, here in SoCal many a buyer are not even interested in Volvo outdrives; only Merc.

Now a guy looking to buy a fishing battlewagon, especially diesel is another story out here.

Mark

 

[HT32BSX115]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

Not an exaggeration here in SoCal as mentioned in other threads. I drive around the lot my boat is storage and I see 1 Volvo and many Mercs.
Same at the ocean boat ramps.




That's a good point as I just mentioned above, here in SoCal many a buyer are not even interested in Volvo outdrives; only Merc.

Now a guy looking to buy a fishing battlewagon, especially diesel is another story out here.

Mark

I really don't want to turn this into a Merc vs Volvo rant. The original poster didn't really ask for a brand comparison....

BUT,

My favorite comparison is to look on eBay in "Boat Parts", 2 separate searches for "Volvo" and "Mercruiser" usually produce approx 3 X more new and used for Mercruiser "stuff" over Volvo.

Just now,

Mercruiser: 31,485 active listings

Volvo: 12,558 active listings

More importantly, If you're going to work on your engine and drive AND you're going to scrounge your parts either on eBay or Craigslist, Boat-Trader, or other parts list, (including dealers), there's just more sources of new and used parts out there for Merc.

The numbers above don't really tell the whole story.

If you're looking for engine and drive parts and components, Mercruiser:Motors/Engines & Components (27,578),
Volvo: Motors/Engines & Components (9,290) (one must note that *some* parts are "the same".... heads, long-blocks, etc)

Many of these are the unique parts that you priced at the dealer (Merc OR Volvo) and then walked away with "Sticker-Shock" pushing you to go to a secondary source, Internet, 1-800 dealer(OEM or aftermarket) for new parts. OR you decide to find something used at the local boat "Wrecking-Yard", craigslist, or eBAY.

When you do that, you obviously want access to the most "stuff" because the market forces prevail here. More supply=lower prices


I did exactly the same when I pulled my old 87 OMG 460 King Kobra out of my 211 Liberator.

There was an advantage somewhat of "Supply/Demand" when I sold all the King Kobra "stuff" I pulled because some of it (Y-pipe, flywheel housing, t-stat housing etc) was not available anywhere at any price and a LOT more than 2 or 3 people wanted them!

I actually looked for a used & complete, Big-Block Volvo Penta Duo-prop combo to replace it with. (I even priced new! $$$$ The new ones were priced approx the same as the similar Mercruiser [uninstalled] )

But, I never found (locally) a used BBC/Volvo engine and drive for sale. I found several Mercruiser SBC & BBC 300+ HP engine/drive combinations.


ymmv......

Rick

 

[Seevee]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

Thanks for all the replies.....

I've pretty much decided on the boat with the Volvo. I like the bigger engine and the brand new drives.

Now, I'm looking for good sources for parts, if anyone can help.

Mostly the basic consumables and replacement items.... plugs, hoses, belts, filters, oil, lube, accessories (starter, alternator, fuel pump etc), for the engines, generator and the outdrives.

Any good sources?

Seevee

 

[QC]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

Here

 

[Seevee]

Re: Comments needed about a 5.7l or 8.1 Volvo engine

Here

QC,

Yes, I do use iBoats for some of my stuff. Had a bad experience, where the guy screwed up the PNs and sent the wrong part, so I ended up paying retail locally to get the job done, and returning it was a PITA, however, I'm not giving up and will use them again. (Hope I don't get kicked off this forum <g>).

Looking for other suppliers, especially of some of the OEM parts that I'd like to find better prices, like the spark plugs, or the fuel pump assembly, which IBoat does not sell.

However, thanks

Seevee