New to outboards fuel usage compared to I/Os

[MIKEHTMSR24]

I would like to know what the difference would be in fuel usage
Let's say we use a 24 foot cat with cabin, I/O, 540 ci, 850 carb, 650 hp, and boat weighs 4200 pounds.
Then we have a 22 foot cat range with a 300 pro max not an X
Speed would be cruising 35 to 50 mph
who will win the gas war??
I know this is a little hard to predict but give it your best shot.

[Tom Brown]

The PM will consume about 30 GPH at WOT and the big block will consume about 65 GPH at WOT.
I'd guess the big block to be a little bit faster (but not a lot) and the outboard to be far more fuel efficient (close to half the fuel usage). That's my speculation.

[tamalewagon]

I would have to agree with Mr. Brown in stating that an outboard will sip gas compared to a big block. My buddy has to fill up at least 3 times more than I do in a week long trip and running the boats equally as much.

[UltraLucky]

Smaller (lighter) Boat with less horsepower will win gas war every time.
Put 2 of those 300's on the 24 & the 650hp in the 22 & i think the outboards would be more thirsty.

[stoker2001]

Smaller (lighter) Boat with less horsepower will win gas war every time.
Put 2 of those 300's on the 24 & the 650hp in the 22 & i think the outboards would be more thirsty.i would agree at cruise speeds,but at top end it would by close and in my opinion the outboards if propped on the lower side would out accelerate and be faster on top

[cougarcat]

Mike, Haven't seen you guys in a while. I boat with the Atlanta Powerboat Club and we see you guys on Murray or Hartwell occasionally. Concerning fuel comsumption......A good friend of mine in our club has a '02 26 Daytona with 300x's and I have a Merc. 575 with the 575 kit from Arizona Speed and Marine in my '01 26 Daytona. He does a little better than me at the pump. Same conditions....I'll burn maybe 65-70 gallons a day and he'll eat up around 60 or so. BUT.......His boat will run 112-114 all day and I'm stuck at 90. New boat with blenders on order for me!!!!!!
Hope to see you guys this summer.
Gerry

[MIKEHTMSR24]

I really didn't know
I would have thought the I/O would have done better in the cruise range but I don't have any experience in O/Bs.
Thanks for the education
Gerry see you at the lake this summer. In something.
Anybody want to buy a black cat
Thinking about down sizing???????
Original owner
1999 HTM SR24
540 ci
683 hp
676 ft/tq

[stoker2001]

I really didn't know
I would have thought the I/O would have done better in the cruise range but I don't have any experience in O/Bs.
Thanks for the education
it really depends on what you mean by "cruise range"?i had a friend with a 600hp blown 23' nordic v-bottom.if he did not get into the boost i think it got better mileage then my out board.if you take a 300hp inboard verses a 300 hp outboard with boat weight being equal then i think the inboard wins in fuel consumption category.

[ToffenG]

it really depends on what you mean by "cruise range"?i had a friend with a 600hp blown 23' nordic v-bottom.if he did not get into the boost i think it got better mileage then my out board.if you take a 300hp inboard verses a 300 hp outboard with boat weight being equal then i think the inboard wins in fuel consumption category.
Hi!
A PM 300 use approx. 15 gallons at 4.000 rpms and 30 gallons at wot.
Cheeers, Toffen G

[MIKEHTMSR24]

683 at 5684 and 676 tq @ 4600
@ 5684 fuel F #/HR = 265.5
fuel is around 6 lb a gal
266 / 6 = 44 gals an hr.