350 Mag/Horizon B3 enough for '06 260?

Back in January I went out and did my own un-scientific analysis. 2006 260DA 496 MAG Bravo III Ratio 2.0, Genny, 75% fuel, no guest.

Best fuel efficiency at 3500. I usually cruise around 3300.

Fuel%20Curve%20260DA%20496%20MAG.jpg

Interesting Chuck.
My same cruising speed 3500-3600RPM, 25.7 Knots and 9GPH.
 
Here are the real world numbers for my 350 MAG. I have posted these numbers several times before. This is from a thread I started two years ago:

I mentioned in a couple of my other postings that I would get some accurate fuel burn numbers on my 260DA from my Smartcraft enabled Chartplotter. I was able to do that today and I have posted the numbers below. First off this is what the Chartplotter tells me in real time.

DSC03096.jpg


This picture was taken as I was idling out of the Marina. All speeds are GPS SOG. The temperature was 85 degrees and the lake was like glass. As you can see we had roughly half a tank of fuel and about the same in the freshwater tank. Only my wife and I were on board. No tabs were used...........only the outdrive was trimmed for the best performance. Please note............some of these numbers may be off a fraction or two because as I was driving along I was shouting them off to my wife who was writing them down and since that takes a bit of time some of the numbers may have flucuated ever so slightly ....such as fuel flow or consumption. I guess what I am trying to say is if any of you math wizards start computing this stuff by hand, it may not exactly match by a hundredth or two here or there. :lol: Since the consumption numbers are stated in gallons per nautical mile , the lower the number the less the consumption. And I need to remind everyone that a nautical mile is roughly 1.151 road miles too in case someone is trying to verify the math. :smt018

Speed/ RPM / Fuel Flow/Consumption

07.7/ 1540/ 02.32/ .36
09.7/ 2410/ 05.86/ .69
15.7/ 3120/ 10.78/ .78
25.3/ 3570/ 12.08/ .55
27.9/ 3950/ 13.37/ .55
31.7/ 4380/ 17.50/ .62
35.2/ 4680/ 20.24/ .65

Running between 25 and 28 mph seems to yield the best overall consumption numbers.
__________________
 
Scotto, a few years back I had a lengthy conversation with a Merc technician. He said they recommend not maintaining over 3600 rpm for "more than a short time".

The reason your cruise feels better at 4100 is because that is getting a better speed for your hull. A 496 will produce the same speed at 800 - 1000 rpm less. I'm not sure how many of you have done engine swaps. Through myself and close friends and family we have done a lot with a number of boats. Going from a small block to a big block in the same boat is very enlightening. You get the same fuel burn numbers at given speeds, but with a motor noticeably working far less.

Todd, you mentioned maybe a desire for a 350 mag. We went from a standard 350 to a 350 mag in the same boat for a 70hp net increase. There was no perceptible difference. That was one of the first swaps we did. We quickly learned to ignore hp and look at the torque curve.
 
I agree with Keokie and if you look at the two charts above comparing my 350 MAG to Chuck's 496 you can see the 496 works a lot less harder than the 350 at the same mph. That engine will likely last longer than the 350.

Just the same, the initial cost difference is staggering when the boat is new and that's why you don't see too many 260DAs with the 496. So in that regard the 350MAG makes sense even if you may shorten it's life somewhat by running at higher RPMs.

On mine I typically run at around 3700-3800 RPM. At 3500 RPM it is barely on plane.
 
I would make the decision based on your anticipated usage of the boat.
Fuel burn/longevity of gas engines are affected by loading. Clearly, small block power in a boat that size is marginal.
If you're going to run the boat lightly loaded in calm conditions, the small block may be sufficient for you.
If you typically take a boatload of friends and their kids out with you- together with all the coolers and gear that accompany them- I suspect that you'll find it may be underpowered.

I would load the boat the way you're going to use it most of the time before taking it for a sea trial. Add enough bodies to equate to a full fuel tank if you need to, and as many other friends as you need to get the right weight in the boat.

Too many people sea trial a boat with a near-empty fuel tank and two people aboard- then wonder why it can barely plane when they load it up for a weekend at the beach.
 
ChuckW and Dave S
Not that this was my thread.
Thanks for posting your performance data.
The fuel burn rates were what I expected.
The 496ci 3000rpm cruise speed is 5 mph slower then I was hoping for.

When I prop my 496ci. I'm seriously looking at Merc Racings Bravo 3 Prop. Double cupped, Designed for mid range performance. Merc Racing has a impressive add for it anyway.
 
Scotto, a few years back I had a lengthy conversation with a Merc technician. He said they recommend not maintaining over 3600 rpm for "more than a short time".

The reason your cruise feels better at 4100 is because that is getting a better speed for your hull. A 496 will produce the same speed at 800 - 1000 rpm less. I'm not sure how many of you have done engine swaps. Through myself and close friends and family we have done a lot with a number of boats. Going from a small block to a big block in the same boat is very enlightening. You get the same fuel burn numbers at given speeds, but with a motor noticeably working far less.

Todd, you mentioned maybe a desire for a 350 mag. We went from a standard 350 to a 350 mag in the same boat for a 70hp net increase. There was no perceptible difference. That was one of the first swaps we did. We quickly learned to ignore hp and look at the torque curve.

I agree. The only reason I would want a 350MAG is for the gooey MPI/Smartcraft stuff. The HP increase isn't worth the jump. Torque in the big blocks certainly is great, but my point earlier is that I like my fuel burn rates.

Chuck's 496 for sure is a great power package, but I'd stay with the 350MAG for the newer models if fuel burn is any concern.
 
I know I can get better numbers out of mine. Back in January when I did that I was having drive and trim issues. They have since been resolved and I plan on retesting In July. When I do I'll post the updated numbers.
 
I'm due for a re-power in the near future. The 5.7L (1992, 4 Barrel carb) has always been marginal. I was thinking of going 6.2L, maintaining the small block so I didn't have to fiddle with engine mounts and the "Y" pipe. Should bolt right up to the Bravo II gear box.
Anyone got any thoughts on this combo ???
 
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Here are the real world numbers for my 350 MAG. I have posted these numbers several times before. This is from a thread I started two years ago:

I mentioned in a couple of my other postings that I would get some accurate fuel burn numbers on my 260DA from my Smartcraft enabled Chartplotter. I was able to do that today and I have posted the numbers below. First off this is what the Chartplotter tells me in real time.

DSC03096.jpg


This picture was taken as I was idling out of the Marina. All speeds are GPS SOG. The temperature was 85 degrees and the lake was like glass. As you can see we had roughly half a tank of fuel and about the same in the freshwater tank. Only my wife and I were on board. No tabs were used...........only the outdrive was trimmed for the best performance. Please note............some of these numbers may be off a fraction or two because as I was driving along I was shouting them off to my wife who was writing them down and since that takes a bit of time some of the numbers may have flucuated ever so slightly ....such as fuel flow or consumption. I guess what I am trying to say is if any of you math wizards start computing this stuff by hand, it may not exactly match by a hundredth or two here or there. :lol: Since the consumption numbers are stated in gallons per nautical mile , the lower the number the less the consumption. And I need to remind everyone that a nautical mile is roughly 1.151 road miles too in case someone is trying to verify the math. :smt018

Speed/ RPM / Fuel Flow/Consumption

07.7/ 1540/ 02.32/ .36
09.7/ 2410/ 05.86/ .69
15.7/ 3120/ 10.78/ .78
25.3/ 3570/ 12.08/ .55
27.9/ 3950/ 13.37/ .55
31.7/ 4380/ 17.50/ .62
35.2/ 4680/ 20.24/ .65

Running between 25 and 28 mph seems to yield the best overall consumption numbers.
__________________

My numbers are almost identical to yours.
 
I don't know for sure but, I think all you small block 260 owners are in denial:grin: My 06 260 had the 6.2 in it and I felt like it was way underpowered with anything more than 2 adults and 2 kids. With my normal loads, it took full tabs to plane it with 6 adults and 2 very small kids. It was OK in calm lake waters but the one time I ran it to the blue water, it struggled in 2' following seas big time. Try putting 2 adults in a tube and 2 onboard and running tight circles to create a large center wake to run through, then you will realize how underpowered it really is. IMO, the deeper 21deg hull of the 05+ needs the 8.1 to be adequately powered.
 
I'm due for a re-power in the near future. The 5.7L (1992, 4 Barrel carb) has always been marginal. I was thinking of going 6.2L, maintaining the small block so I didn't have to fiddle with engine mounts and the "Y" pipe. Should bolt right up to the Bravo II gear box.
Anyone got any thoughts on this combo ???
I have not heard anything good about the 6.2 engine.
I have heard some bad things about it.
The 383ci is a engine lots of people like.
Merc has one in a EFI version.
 
I thought the 383cid was a 6.2L. I was planning on installing one with FWC (all salt water here), and MPEFI.

Anyway, that's why we ask on the forum, learn new stuff every day.
 
I thought the 383cid was a 6.2L. I was planning on installing one with FWC (all salt water here), and MPEFI.

Anyway, that's why we ask on the forum, learn new stuff every day.
Merc says this engine is 320 prop Hp and 390 lbs tq.
I was told you can get it in a FWC.

A 6.2 may be 377ci Has a shorter stroke then the 383ci.
Check www.marinepowerservice.com Has the 6.2 and 383ci. www.perfprotech.com has the 383ci and a 377ci (6.2 ?)
I just now looked this up. The info and pics are from today.
During my long research on best power packages.
I heard some older 6.2ci had engine problems.
one new 26 DA with a 6.2 could not hold plane at 4000 rpm even after numerous trips back to the dealer. Another 32' with twins needing to spin 4000 rpm also.


I read a engine test on,...The 6.2 Merc and Volvos 5.7 320 hp engine. They are suppose to be a big block replacement engine. 370tq for Volvo/ 375Tq for 6.2.
The Volvo got better MPG. The 6.2 got better mpg at WOT.
Testers sid the 6.2 may be a better choice if your WOT all day. The test boat was something like a 25/26' Crestline.
The 496 matched there MPG at 2500rpm maybe gave up 1 GPH at 3000rpm and smoked them both in performance.
 
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I thought the 383cid was a 6.2L. I was planning on installing one with FWC (all salt water here), and MPEFI.

Anyway, that's why we ask on the forum, learn new stuff every day.

It is.

I haven't heard anything bad about it, but that it is no longer offered from Merc. There may be a few out there still.
 
Back to the origional thread topic: From my experience with my 270 WE, the 350 MAG Horizon would only just make it in good weather. But I don't know the weight of an '06 260. My Weekender is just on 3 tons ! (Dry)

My research (while you guys were all asleep !!) seems the 6.2L comes as a 377cid and the 383cid (stroker) at 320HP and 350HP but both quoted as having 390f/lbs torque. Both available in FWC.

Prices here in Oz, $25-$27000. So I think when the time comes, I'll import one (a 383cid seems the way to go) from the USA where the cost is down to about AU$9-10k with shipping !!
The old 350 will sell here for $4000-$5000.
 
Back to the origional thread topic: From my experience with my 270 WE, the 350 MAG Horizon would only just make it in good weather. But I don't know the weight of an '06 260. My Weekender is just on 3 tons ! (Dry)

My research (while you guys were all asleep !!) seems the 6.2L comes as a 377cid and the 383cid (stroker) at 320HP and 350HP but both quoted as having 390f/lbs torque. Both available in FWC.

Prices here in Oz, $25-$27000. So I think when the time comes, I'll import one (a 383cid seems the way to go) from the USA where the cost is down to about AU$9-10k with shipping !!
The old 350 will sell here for $4000-$5000.
Check out the updated post #56
 
Since we're posting some some numbers, for comparison sake: I can't offer GPH as I've never had the option to run the boat at one RPM for 5 or 6 hours straight and then fill-up. But, I was out yesterday with 4 adults, 2 kids (and of course the kid's stuff), a tad under 1/2 tank of fuel. Full water and hot water tank. Nothing in the waste tank.
I thought of this post, and it made me wonder what kind of speed I get at a certain RPM. With my 5.7L EFI 260HP, I get 31MPH at 3,850RPM. Also, with 3 adults and 2 kids, it pulls me out of the water on one ski with no problem. :grin:
 

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