5.7l horsepower?

[Tom97Sundancer]

Can anyone tell what the horsepower is on a 1997 5.7L mercruiser motor? The boat is a 1997 searay sundancer 240. The reason I ask is I/m barely getting 30 knots on a 14.25 x 15 ss prop at 4600 rpm's and I think it should be able to go faster(one person in boat, full tank of gas). How bad is it for the engine to cruise at 4000 rpm's to get 25 knots?? Thanks for any input.

 

[navigator336]

Re: 5.7l horsepower?

Most likely 260 or 270 horsepower. I think the Vortec engines came along in 1998, but I'm not sure. If the block has a sticker on it that says Gen Plus or Gen 1 Plus then it should be a Vortec and have about 300 hp. If your engine is carbureted, you're probably into the secondaries at 4000 rpm and sucking the gas. How do the plugs look following a 4000 rpm run?

 

[Tom97Sundancer]

Re: 5.7l horsepower?

Navigator-the engine is carbureted and I'm almost positive it's not a Vortec. I'll take a look at the plugs after the next go round at 4000 rpm's, what should I be looking for?? Does my speed seem normal for that engine/size boat? What can I do to increase my speed? I know I have an Alpha 1/Gen 2 outdrive, but is it possible it has the wrong gears in it to prevent me from getting the speed I think I should be getting?

 

[rml]

Re: 5.7l horsepower?

FWIW, nadaguides.com shows the '97 240 Sundancer w/the 5.7L to be 210hp. Also shows the boat to weigh in at 4500lbs - quite a bit of boat. I would research prop options to get a higher top end.<br /><br />Regards,<br /><br /> --rml

 

[navigator336]

Re: 5.7l horsepower?

I assume your carb is a four barrel. If so, I think the nadaguide has a typo. The motor should be 260 or 270 hp. If it is 210, you're doing pretty well at 35 mph. I think you ought to get more out of it on calm water, but I've never owned a boat of this particular size and weight so that's only a guess. You could call a Sea Ray dealer and ask them, they should know the boat well as it isn't that old.<br /><br />The plugs should be a light to medium tan color. This tells you alot about tuning and fuel/air mixture. If they're black and covered with soot, it's running too rich and probably not making as much power as it should. If you go on line, you should be able to find pictures of spark plugs in various states. Try searching with "condition of spark plugs or reading spark plugs".

 

[navigator336]

Re: 5.7l horsepower?

I forgot to mention, you are at the right WOT rpm range now. However, if the engine is not making full power, or, there's a problem with the hull, or the drive, or the prop itself, then with those conditions corrected, you would be able to spin a bigger prop and increase your speed. How's the prop look? Have you ever taken it to a shop with a computerized pitch measuring machine?<br />In regards to your drive ratio, if you're getting 4600 rpm at WOT, I doubt it's wrong for your boat.

 

[Bondo]

Re: 5.7l horsepower?

30 knots....<br />That's about 35mph........<br />I'd say you're doing Pretty Good,<br />For a Boat that Size.....

 

[xltier]

Re: 5.7l horsepower?

my friends 25 foot crownline with a 350 4-barrel doent do any better.do u have trim tabs.i hear they help alot.

 

[Tom97Sundancer]

Re: 5.7l horsepower?

Navigator-the prop is brand new, ss 14.25 x 15. I wanted to get a 15 x 15 but West Marine/Boat US didn't carry that size. Would a 15 inch prop make that much of a difference?<br /><br />Bondo-how bad would it be to run the engine at 4000 rpm's to cruise at 25 knots? <br /><br />I appreciate all the feedback, it helps a great deal.

 

[wvit100]

Re: 5.7l horsepower?

running a 4000 rpm's is pretty fast for extended periods, redline is only a couple hundred rpm's away. my 350 feels like it wants to cruise around 3000. at 4000 you will be using a lot of gas, but as long as it doesn't overheat and has plenty of fresh oil with good oil pressure it should be ok.

 

[MFG197]

Re: 5.7l horsepower?

The 5.7 also comes in a 4bbl 250 hp iteration. Mine is a 96 5.7LX on a 21.5 Sea Ray cuddy. Is there no plastic cowl on the top of the carb that says the model and or HP?