Here is a scenario I'm sure has been beat to deth.two boats same day same water. 100 mile trip 3500 rpm.
Boat one. formula 271,502 completely stock
Boat two. donzi 28 ,twin 350 mag

App how much more fuel would boat 2 use?

The twin engine boat will be running much faster at 3500 than the single, 502 and 454 will burn very close to same amount of fuel. So approximately 80% more on twin? 502 is 415 hp the 454 mag is 385hp

wow almost double

I think he said the twin boat was running small blocks not 454 mags. But I agree that the twin will be cruising faster and you'll have alittle less strain on the motors.

I've heard that at wot a boat will burn 10 percent gph of the horsepower. So say a 502 mag 415 hp will burn 40 gph at wot and just say a solid 20 at 3500 rpm.

Now twin 350 mags are rated 320 hp? 350 hp? So say 65-70 gph wot for both motors and cruising like 28-30 gph. So 33 percent more ?


I could be wrong on my math any twin engine boat I've ever wrenched on or been on no one looks at the fuel consumption. Just chalk it up as a fun tax.

But you'll get there faster with the twins, I don't have twins but everyone loves them! Lol

Maybe someone more intelligent then myself will chime in.

You changed your story from 454 mags to 350's! ...Either way you would be surprised how little difference there will be in fuel burn. Sure the twin 454's will use a little more than the 502 per hour, but you will be going faster. I actually use less gas in a 30' boat with twin 425's than I burned in a single 24' boat with 575-600 HP. Not exactly the same scenario but you get the idea.

That being said, twins make life so much easier in so many other ways that I would not let that deter me if I was worried about cost. Gas and oil changes are the cheapest part of boating.



-Artie

...However at WOT it will use DOUBLE the fuel. No way around that one!

The difference will not be huge either way. Whats an extra $50 when you're spending around $300 on fuel.

$300 on fuel? Must be a rowboat. Lol. I have and love the twins and would never go single again. But with a 130 gallon tank $300 is only about half a tank. Lol. I don't have the exact figures yet as I haven't finished flo scan but best estimate so ft is somewhere around 1.5 mpg at cruise. Not horrible and not much different ten my old 20 sea ray with a single 350. Plus cruise for me is around 40. So your making better time anywhere you go.

His original post said 292 with 454 mags, then he changed it. And yes 80% more is nearly double

I was just trying to get some idea on how much a 27 with the 502 would burn compared to next step into small twins.the majority of ppl on here say they don't watch how much it cost them in gas so my question is on average how much does everyone burn in a weekend and what boat set up?