88 268 fuel consumption

G

G Wilikers

New Member
Aug 29, 2010
23
Southern Calif
Boat Info
1988 Sundancer 268
Engines
gm 454
Was wondering what is the general range of an 1988 268 sundancer w/ a single 7.4 & 100 gal tank? How can I figure what the most fuel efficient rpm is? What would be the top speed? All this is considered w/ the original drive & a stock rebuilt engine.

Thanks,

Greg
 
Depends on a lot of factors, but I want to say 30 to 35 is the top speed depending on state of tune, altitude above sea level and amount of "stuff" carried aboard. The optimal cruise for the 7.4 is usually around 3,300 rpms. On your boat it might be a little higher due to the weight and deadrise. The 268 is a great boat but it really needed a 502! You want to be on a clean, crisp plane. A friend had a 268 and it seemed his best cruise was around 28 mph or so. RPM's were higher than my 250 DA with the same engine and outdrive setup. Seems like I'd be running 3,200 and he'd be around 3,600 or so. It's been many years since we did that, so I may not have the numbers right!

The other thing to take note of, is the Alpha 1 is rated for 300 hp while your 7.4 is capable of producing 330 hp. If you are easy on the drive it should last a long time. If you go from dead stop to full throttle, it will take it's toll on the drive and you run the risk of damaging the gears.

I'd estimate your mileage to be right at 1 mpg. That's a total guess, but is probably reasonably close until you can start comparing trip distances traveled with gallons consumed.
 
A good running 7.4 in a 268 with moderate load and clean bottom should top out right at 40 mph.

Like Sundancer said, 3300 is likely the best cruising RPM, giving a speed of 26-27 mph, burning around 15-16 GPH. Best cruise should provide at least 1.5 MPGs, giving a safe range of around 125 miles.
 
I think 1.5 is pretty optimistic. In our 250 DA, we rarely got 1.25 and most of the time it was less. He is at sea level, but I don't think it will make that much difference. I had troubles hitting 40 mph in a much lighter boat with the same engine and outdrive.
 
Sundancer said:
I think 1.5 is pretty optimistic. In our 250 DA, we rarely got 1.25 and most of the time it was less. He is at sea level, but I don't think it will make that much difference. I had troubles hitting 40 mph in a much lighter boat with the same engine and outdrive.
Click to expand...

Well, you have to figure --- 3300 RPM gives at least 25 mph, right? (if propped correctly) And a 7.4 burns no more than 16 GPH at 3300 RPM, right? So, that equals at least 1.56 MPG. I think you'll find that the 268 owners with clean hulls and good running engines are getting at least these numbers.

I don't know for certain about the top speed --- but, I do remember reading that some 268 owners with the 7.4 have reported top speeds of at least 40 mph. But, it is possible that those boats had the Bravo I drive.
 
EricW, you could be right! I never had our 7.4 at sea level! The numbers SEEM right. And maybe you CAN hit 40 at sea level in a 268! I'd guess a few more rpms for a 25 mph planing speed, but not enough to lower the fuel consumption that much either. There are so many variables like props, water condition, weight loaded on to the boat, trim, etc.....
 
I have a A-1 and have gone past 40mph when low on fuel, and light load...It happens..Approx. 500 ft above MSL.
 
Popeye, what have you experienced in terms of miles per gallon or gallons per mile? :grin:
 
Sundancer said:
Popeye, what have you experienced in terms of miles per gallon or gallons per mile? :grin:
Click to expand...
I have never checked .....I lake boat and never really go anywhere. I believe the numbers of 15 gph @ crusing speed is about right for me as well.:thumbsup:
 
In the beginning of the season, before ALL my gear was onboard, my WOT is at 4200 rpm's, and Im over 40 mph (according to the speedo)..

Durring the season, with gear on board, full tank of water, 3/4 fuel, I can still hit around 3800-4000 or so and about 35-38 mph..I can get to the canyons pretty smoothly like that, but running WOT for almost 3/4 of an hour will burn a nice amount of fuel..Its not terrible, tho....but to be honest, I havent really took notice what my GPH is..

If I just cruize 2800-3200 rpm's, my consumption is not too bad at all.

Like Sundancer said, there are variables, prop pitch, size, water conditions, you can play with the trim tabs, with the outdrive angle, ect...

My 7.4 in my 268 is actually .40 over, which I believe is a 462..

:grin:
 
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AntVinTas

I'm curious about your transom and what appears to be a seat back there. Do you have a collapsible seat bench?

If so...could you possibly post a picture or two of it?

I want to build a transom seat for my 268 this fall/winter.

Thanks.
 
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I'm new here and we are contemplating buying an older sundancer in the 268- 270 range. I'm wondering how you guys feel about the 350 versus the 454?

There is an 89 268 close by we are waiting to see but it has the small block.

Does the small block have the guts to move a big boat?
 
Depending on the the amount of cargo, and bodies on board will be your big determining factor. Personally, I would stay away from the small block, unless it was supercharged. This boat really is to much for the 350.
 
Like BBY said, stay away from the small block. It's too small for these boats, plus you need the extra weight of the big block to balance out the boat better.

My philosophy is to get as much motor as you possibly can get. You can always back off the throttle.:grin:

These boats are going to burn some fuel. If it is a concern, this might not be the right boat for you.
 
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I had a friend that started out with the 268 it was his first and only boat. He was concerned about how much fuel it would burn and the cost. Told him to figure on a gallon a mile, after 5 years of hearing him complain about the fuel costs on a boat he only took out 3 or 4 times over the summer he sold it. To this day he still complains about all the money he wasted on fuel. Fuel is not cheap but if you are not prepared to pay the price to go use a gallon a mile then don't buy this boat, start out with a bow rider and get use to the fuel consumption. Boating should be enjoyable and shared with the family you might do what I do and that is to budget what I will spend on fuel for the 4 months that we really get to boat. It does not matter if you plan to spend $1,500.00 or $4,000.00 what can you afford to spend over your boating summer.

Ken
 
well on my 88 268 Sundancer. with 4 adults and 2 teens, with about 90 gal fuel and on the ICW with smooth waters i was doing about 42 mph. i have not done any consumption studies yet. i keep the boat stocked for fishing minus the ice and drinks and bait. i estimate the weight to be about 5k for the boat + 2k in pax and gear. it is a cruiser and takes a little to get going that fast but i generally only cruise at about 25-30 depending on conditions and traffic. about 21-2400rpm i think. all things considered. i love the boat, its the perfect size for me and my 2 kids and there friends, the wife is now the X so that much better lol (no i didnt toss her over, i wouldn't want to scuff the oxidation, but the 260lb reduction in weight and the noise reduction greatly improved the performance and pleasure factors :) I'm in Afghanistan at the moment and have only had the boat since 09 and have been out about 20 times. i really need to get a logbook and come up with a name for it.
 
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