gas engine choices for a repower

[bud37]

Ok engine gurus, opinions on who is the best to repower with, a 20,000 lb boat thru RV drives.....mercruiser, crusader or volvo penta........I know that diesels are better but the cost is just unrecoverable in the short term imo.

Would you get the complete package,fuel injected etc or just the engines or the long blocks and swap out all the stuff you already have which would be carbed. Mercs are already there....Thanks as I have never done this before...

[Viper]

Source of the post Ok engine gurus, opinions on who is the best to repower with, a 20,000 lb boat thru RV drives.....mercruiser, crusader or volvo penta........I know that diesels are better but the cost is just unrecoverable in the short term imo.

Would you get the complete package,fuel injected etc or just the engines or the long blocks and swap out all the stuff you already have which would be carbed. Mercs are already there....Thanks as I have never done this before...

Mercs aren't at the top of my list but they do have the best infrastructure in place which really helps when you needs parts. Just about every marina will carry Merc parts or can easily get them. Crusader and Volvo, not so much however they are very good brands in my opinion.

Going with Merc long blocks would be the cheapest way to go. This way you don't have to replace everything or modify to accommodate another brand.

Going with EFI depends on a couple of things in my books; again, not only will it be more expensive for the unit but you'll likely have to replace a few other things depending on the vintage you go with if it's used units and most definitely if they're new. I'd also consider whether I'd be keeping the vessel for the long haul or would I be selling in the foreseeable future. While you may recover some of your money, the next buyer certainly won't give you the money you put into it for the repower. They may be new engines but it'll still be an older boat (how old is the boat?) and that will affect a buyer's perception of value/worth no matter what's been done. There comes a threshold where you don't recover the value that you put into it. Having said that, if this is your baby, and you plan on keeping her forever, then you can throw the "investment" way of thinking out the window since that only matters if you're selling. If that's the case, then let your wallet dictate (it will anyway) and get what you want/need.

The model and build of the vessel would also dictate to me which way I'd go as far as how much money I'd put into it given that some builds are more prone than others when it comes to requiring major structural repairs such as stringer replacement. If there's wood in those stringers, or a cored hull, I may thing twice about putting thousands of dollars into recent engines knowing that it's likely I'd eventually have to deal with bad stringers in either a repair or diminished value as a result when I try to sell. In my case, I have no wood stringers or cored bottom to worry about and the rest of her is still solid. Even if I had to do major work topsides, it would be nowhere as bad as a stringer job. Given that I plan on this being my last boat and really don't care about a return on investment, if the wallet allowed, I would go EFI and if I hit the jackpot I'd go diesel.

[tomschauer]

I pretty much agree with viper, only a few exceptions. If you are going gas, 5.7 or 7.4 the blocks are GM, not Volvo, or merc or crusader. So the base is identical.The bolt on parts are by the others. If you get a remanufactured engine(s) I would make sure you get a newer (96 and up) or new base engine with a roller cam etc. More HP less friction longer life. If you go with merc, you can use most of your existing parts, wiring etc. Saving some time and dollars. If you go with complete new engines, I would go fuel injection, easy starts, smooth idles pretty much plug n play.
As viper says, if you are going for the long run, put some little diesels in there. Volvo or Merc (cummins) 4cyl will push 20k lbs as well as a 7.4 ( a bit slower out of the hole) for about half the fuel burn. If you have a genny, you will need a separate tank or replace it with a new diesel $$$$

It all boils down to your budget....

[Viper]

Source of the post ...the blocks are GM, not Volvo, or merc or crusader....

+1 however my recollection is Merc and Crusader for example used different versions of the block. All external hardware would still bolt up but there were some differences in the block's build. If I recall, it was heavy duty truck application versus passenger car application. I seem to recall that Crusader used the heavier duty build. Don't remember if I got that from previous rebuilds or documentation. Would have to go through some paperwork to confirm. The later builds may have all been the same though as I'm sure they scaled back production once they made a decision to eventually mothball the block.

Agree with post '96 block is the way to go.

A couple of Volvo D6s would look sweet in mine

[tomschauer]

https://www.summitracing.com/parts/hpe- ... /chevrolet
Here's something to look into if you have 7.4's currently. A 415hp marine long block for under $3800.

[bud37]

Thanks guys ,now this is very useful info.....I know that all the 7.4's are GM blocks, just no idea what the different marinizers are doing to them, or not doing to them.After having read some bad info on Merc exhaust manifold problems as far as water ingestion, is that a concern in these boats ??...( early 90's Carver)

My take on diesels is that the low hp (under 300 ) is the only way to go, with the naturally aspirated 150hp fours lasting forever......I think you need a serious bank account to care for and run anything with a turbo, just my two cents.

Just read that last post ,huh maybe if this deal goes thru we could pick up a couple on the way back from south next spring.....bought lots from Summit over the years racing......good call.

[tomschauer]

Pretty much all the new turbo diesels are bullet proof. If you go with naturally aspirated, you will need a larger displacement (much larger and heavier) engine to produce the same hp and torque as a turbo.

[tomschauer]

also, I forgot, I believe it was the horizon engines that had some water ingestion issues, not the standard mercs.

[bud37]

Source of the post also, I forgot, I believe it was the horizon engines that had some water ingestion issues, not the standard mercs.

What is the difference between the Horizon and the standard, I have heard that horizon name before, can you tell by looking at them ??

[tomschauer]

They have a bit more HP. Should read Horizon on the air cleaner.