US engine repower

[ReefRaider]

Anybody done business with this company?

http://www.usengine.us/mercruiser.html?gclid=CPnT_JqhlpoCFQOjFQod8zmsMg

If so, any good / bad experiences to share? I am looking for something to repower my '93 350/5.7 merc (260 hp). Do any experts on this board have any comments on their "sell"? They are recommending I go with the 300hp 350 "performance" engine, will have more power and use less fuel. Isn't that an oxymoron? Thanks in advance.

 

[QC]

Re: US engine repower

I have no experience with them, so I can't comment on their quality, but . . .

They are recommending I go with the 300hp 350 "performance" engine, will have more power and use less fuel. Isn't that an oxymoron?

This can actually be true. It is very hard to dispute without data, so it is easy to make that kind of claim. With that said, if the higher rated engine's combination is more efficient then yes it can deliver better fuel economy. That is generally not true if you use the extra power to go faster, but it is possible that a higher rated engine could deliver better fuel economy at a specific cruise speed as compared to it's weaker sister.

A good example is multi-point efi engines vs. a carbed engine. I understand that is not the case here, but to illustrate the point. A 300 MPI 5.7 could indeed be better on fuel at a 30 MPH cruise speed than a 250 bhp carbed 5.7 at the same speed. Many will say that is because the 300 is not working as hard, but if the engine's are running exactly the same RPM for the same speed (same prop), same displacement, then they are actually working equally hard Sooo, why would the 300 be more efficient in that example? Better control of air fuel ratio in each cylinder and every firing event. That one is kind of easy.

Also, if the engine's additional horsepower allows you to go up in pitch on the propeller, the RPM would drop for the same cruise speed. In this example, the throttle opens up slightly and pumping losses are slightly minimized, and fuel efficiency improves. This example drives people crazy, but if you can lower RPM, and open the throttle more, then efficiency improves against the same load (moving the boat at 30 MPH).

Finally, imagine both. More efficient technology and configuration, plus higher rating allowing the lower RPM operation for the same boat speed (same displacement). Then you get two pluses that theoretically should improve fuel efficiency and you might even notice . . .

 

[180shabah]

Re: US engine repower

QC - that was a great, easy to understand explanation, but i bet somebody still comes back with, "but my brother...."

Reef - Of course they are suggesting the higher output, it cost more. One thing to remember, though, a 40hp increase will likely require a prop change, unless you are currently running at the bottom end of your WOT range. Just one more expense to consider.

Questions you need to ask before purchasing. Is that 300hp rated at the crank or at the prop? An alpha drive eats about 30hp, so keep that in mind when comparison shopping. What are the differences between the 260 and 300hp engines. carb? intake manifold? heads? cam?....

 

[QC]

Re: US engine repower

QC - that was a great, easy to understand explanation, but i bet somebody still comes back with, "but my brother...."

Thanks and his brother may even be right . . .

 

[180shabah]

Re: US engine repower

OK, so I actually went to their website, and they do not give me the warm fuzzies.

"Includes Marine Long-Block, Gaskets
Our Mercruiser Engines Are 100% Marine NOT Auto Engines That Others Sell as Marine Engines "
What makes a block marine insted of auto? Nothing other than the paint, which they do not include. All of the differences are in the component choices.


"Automotive Engines Use More Fuel And Have Much Less Power "
Again, this is all about component choice, not auto vs marine.

All of the hp claims are "around" X hp at 4600-5000 RPM. This tells me there is no actual data to support them. All of the "works with EFI without requireing any reprogramming" is prefaced with, "and we have tested it". I don't read this as "optimized for FI", I see, "we finally got a combination that doesn't throw codes".

have you checked with a local engine builder to see what they can build for you?

 

[ReefRaider]

Re: US engine repower

I don't really have any local engine builders, depending on definition of local. Do have mechanics to help with the exchange. Thanks, I understand the possible better fuel economy depending on the running RPM's. Basically just looking for a new or remanufactured engine, price is of course a factor but not afraid to pay more for something "better". Never done this, don't have any first hand knowledge of any engine business, and not about to click "add to cart" without knowing or hearing something about them. If I don't hear any experiences with US Engines...good or bad..., I think I might go Rapido. A lot on this forum sure seem to like them. Thanks again.

 

[boatguya1]

Re: US engine repower

I've had good luck with numerous motors from Rocky Mountain Marine.

James

 

[ReefRaider]

Re: US engine repower

Isn't "had good luck" and "numerous motors" also an oxymoron? Just kidding, I'll google it and check it out. Thanks.

 

[AZSenza]

Re: US engine repower

Their prices dont look bad but I want to know everything about the motor, what kind of pistons (cast, hyperutectic, forged) camshaft lift, duration and lobe separation, crankshaft material, connecting rods, what type of bearings do they use? Are the heads magnafluxed? What kind of valves and valve job and what kind of seals are used? Those are questions you can ask them and expect to get an answer for and that would answer the buy or not question.