Fuel consumption

ChromeDome said:
The consumption is dictated by the amount of power you demand. I think your engine came in versions producing from 235 to 290 hp depending on version.

If you demand 200 horses to work, you´ll have to feed them. Or, in other words, if running your boat at a speed where the effort to drive it vs. the speed is low, the comsumption per nm or hours will be lower. Also keep in mind that the hours spend on board without running the engine (anchored, swimming, sun bathing, enjoying cold snacks) will be free (fuel wise).

It is a planing hull so the sweet spots are just above idle and at lowest speed where it is at a stable plane. Thus giving it enough throttle to get on plane quickly, then reducing throttle until it remains on a true plane, will produce economical cruising.

Weight is your enemy so keep it light by removing unneeded gear.

The engine is Ford based, marinized by OMC. OMC filed for bankruptcy 22 December 2000 and parts are becoming still harder (impossible) to find, so keep a close eye on things. Due diligence is crucial.

Repowering commonly is not economically feasible. Would involve a complete engine+sterndrive+instruments replacement - and then some.
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the block and heads are full rebuilds , new manifolds , its only the outdrive id assume to be a potential issue , all new oil and impeller .
being a ford lump most parts seem to be available thanks
 
darren west said:
im very new at this , so im afraid I really dont know what im hoping for , just some exploring , little fishing , visiting a few pubs
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I've always seen burning fuel as a positive, if you are burning fuel you are out having a good time.

I think circa 200 litres will be plenty for you. We have 260 in ours (8m 350hp) and its never been a problem. Just plan your trips accordingly and you will have a great time.
 
thanks for the reassurance

can anyone confirm its just std unleaded and not the liquid gold stuff
should I be adding a additive
 
I can't be certain,but I'd be really surprised if it need super unleaded. It's not a massively tuned engine ,being 5.8 litres capacity and around 250 to 300 bhp.

Run it on normal unleaded to start with and see how it goes.
 
Hi...I am almost certain that you could burn less than that, at cruising speed in the low to mid 20's. Very similar 5.7 GM carb engines will burn about 80 litres per hour at full throttle and about 4800 rpm...if you get the prop right, you could likely sit on plane below 3000 rpm and mid 20's....burning around 30/35 litres or close (at a guess) an hour. well propped, likely less.
I have a 300hp V8 Mercruiser mpi in my boat that can cruise around 2150-2200 rpm and mid to late 20's mph...it will use about 17/18 litres per hour or close at that..perhaps an exceptional example, but just a reference on what modern mpi engines can do, when well set up perhaps.
I would also say that you don't absolutely need to run it on super unleaded either...lots of bad advice going around about this just now. If you do the right things, it will be fine with normal fuel.
 
While working out theoretical fuel burn is useful to a point as others have said the time spent fast on the plane is usually not that long.

I think it is better to find out average daily use from real world. For example in my little 4.5 m rib with an old 60 hp 2 stroke and for a day out of mixed use in the boat I generally use about 20 ltrs. Never more than 30 ltrs. The truth is you do a lot at low speed and less at high speed.

with my 115 hp 2 stroke and 17 ft Fletcher for a similar day out it is about 30 - 40 ltrs.

Pleasingly you never seem to use as much as the theory would have you believe.

I also think there is a lot of scare mongering about the E10 petrol and feel it will be ok in your boat
 
darren west said:
the block and heads are full rebuilds , new manifolds , its only the outdrive id assume to be a potential issue , all new oil and impeller .
being a ford lump most parts seem to be available thanks
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Ford parts may be available, the hard to find parts are the marinized bobs and bits. With new manifolds one risk is gone so that is great.
 
I used to have a 260hp 5.7 V8 in a similar sized boat. I installed a fuel flow meter and would usually see between 10 and 12 Gallons per hour at speeds in the low 20’s. It used to get very near 20gph if I got throttle happy! My engine had a carb. If yours is fuel injected it may be slightly better, but I think 40 lph is probably slightly low.
 
madabouttheboat said:
I used to have a 260hp 5.7 V8 in a similar sized boat. I installed a fuel flow meter and would usually see between 10 and 12 Gallons per hour at speeds in the low 20’s. It used to get very near 20gph if I got throttle happy! My engine had a carb. If yours is fuel injected it may be slightly better, but I think 40 lph is probably slightly low.
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At 3000 rpm on that engine…you should use about 33/34 litres per hour. Well propped, most would be planing at that, I’d think. All about the prop, as you’ll know.
 
darren west said:
the prop is the one the boat came with , I honestly dont know how to tell if its right or not
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Several calculators out there weight might be more difficult to establish but is most important part of the equation! Although if it’s lifted a weight cell will give answer
 
darren west said:
the prop is the one the boat came with , I honestly dont know how to tell if its right or not
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First find out the engine manufacturers stated max rpm for that engine.

Then Get the boat on the water, loaded up with a similar amount of gear ,people,fuel as you expect to normally carry, ensure the hull,drive and prop are clean of any fouling, and take the boat up to full throttle, adjust the drive trim to the optimum position and see what revs the engine is turning at. If it's sitting at or around the engine manufacturers max rpm then the prop is probably about right, if it over revs significantly then the prop is too small,,try a larger pitch and or diameter prop, if it under revs significantly then the prop is too large, try a small pitch and or diameter prop.

Don't let the engine over rev by too much if the prop is too small.

Alternatively, find out for certain what year the boat is then download the fast facts pdf for that year from the four Winn's website, find your boat and engine combo and look at the table for the recommended prop size and compare it to the prop fitted to the boat. The prop on the boat should be stamped with the pitch and diameter info for you to compare with the four Winn's info in the pdf
 
Does the prop look perfect? No chips, dings or bend blades?

The engine max rpm at WOT should be 4400 (my guess as your actual engine version is unknown).

If you reach close to this the prop is right for your GW, if not the hunt for a different prop might start.
Rule of thumb is that one inch less pitch gives 200 rpm more, and since props normally comes in 2 inch steps, the next available prop pitch should change rpm by 400.

If you have any functional problems like rpm going up without the boat following, a different prop type/design could help.

If comparing to manufacturer data make sure you compare to the same gear ratio as your sterndrive.
 
all very good advice regarding props however I would add that it is easy to become obsessed with props. They are not cheap to buy or indeed easy to swap over on the water. So messing with them is expensive and a lot of faffing. If you can establish that your prop is correct before you put it in that is the best thing you can do
 
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Bigplumbs said:
all very good advice regarding props however I would add that it is easy to become obsessed with props. They are not cheap to buy or indeed easy to swap over on the water. So messing with them is expensive and a lot of faffing. If you can establish that your prop is correct before you put it in that is the best thing you can do
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Yep. Despite the marketing hype for stainless my experience it that 80-90% of performance is due to design, the rest at best is due to the material. Completely different game (and price) if talking high speed competition.

Composite never did it for me either. As for brands I´ve been happy with Quicksilver and Michigan and impressed by some specialty labbed props (priced like 24 kt gold). The 3rd party props I’ve tested performed ok for their price, but never better than OEM as claimed.

3-blade is the common and universal standard, for special uses 4 or even 5 blades can be the rigth choice.
 
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