Fuel consumption diff between triple 2.5 carb and 2.5 EFI??

[dkwestern]

What do you think the fuel consumption difference will be between triple 2.5 200 carb engines, and triple 2.5 EFI 280's on the same 6500 pound offshore V-Hull??? Any input in appreciated.

Also cruising speed useage, as well as top end useage. I mostly cruise 4000-5000 RPM. I don't think cruising will be that much different, but am curious what you think. Thanks, Darren

[Pro300x24LD]

What's up Darren?

I do not have an answer to your question, but smartcraft tells me that my 300x burns 35 @ wot and about 15 @ 3500-4,000 RPM's. Of course I only looked once then quickly switched to a different reading.

[eli]

200's at 4500 rpm get almost 5 mpg so it should be good, dont know about efi mpg.

[dkwestern]

Thanks guys, just to clarify I currently have the 200 carbs and am toying with the idea of going to the EFI's and making the boat into a missle, but haven't decided if the cost is worth it.

UP ROKTOY, I should be out Saturday on the lake somewhere.

[Pro300x24LD]

Thanks guys, just to clarify I currently have the 200 carbs and am toying with the idea of going to the EFI's and making the boat into a missle, but haven't decided if the cost is worth it.

UP ROKTOY, I should be out Saturday on the lake somewhere.
Might not be a bad day to go for a ride.....If I get down that way I'll call jason and try to catch up with you guys.

[Dd24skater]

I went from a 200 hp merc carb to bridgport EFI on a 17 Hydrostream Vector, If I had to guess I would say Double the fuel going to the EFI!

Hope that helps

Dd

[YELLOWSS]

double!!!!!!!!!!!!!!!!!!!!!!!!!!!
200 to a 280
i have a 575 lbs allison with a modified 260 efi.
i can run 40 mph @ 2500 rpm and get 6 mpg.
i get maybe 1 mpg @ 7000 rpm
and this is with a 15 1/4 x 32 prop
when i run my 28 prop it goes way down.
if you want to haul a** get trip 260's
if want gas milage and have a fatter wallet stay with the 200's
roy

[1BadAction]

not to mention the motorola box on the 280 is curved much closer than the older EFI stuff. im getting 7 mpg at 6000 to 6500 with a 30et. although thats on a hull that doesnt weigh much at all.

[Redneck]

My carb motor sucks down the fuel. Bigtime. Now I have to get a few things to get my 280 mounted on the boat and see how it does. Hopefully better than the carbs.

[TD]

Also depends on the hull that you have. A 20' Checkmate will have more drag and use more fuel than a 20' Allison will at same speed.

[dkwestern]

IF I could get double at cruise that would be worth the switch alone!! Much less the added HP and speed gains, and a 90+ MPH 33' rocket!!

[kimswang]

IF I could get double at cruise that would be worth the switch alone!! Much less the added HP and speed gains, and a 90+ MPH 33' rocket!!

I'm far away from 90MPH, but working on it with this setup on a 34 Scarab SS... 4.0 V8 Carb X3... Will go MAD EFI when the budget alows for it.

[kds]

if i was u i would put on a pair of 300x because the weight difference would be less by 200 pounds,more engines and more weight is more gas.the pair of 300x is more horsepower than the 3- 200 and u would be closer to 90mph.i have a friend with a 33 powerplay and his boat is better on fuel and is much faster than when it had on those 3- 200's.i have a 25 powerplay and i am putting on a pair of 300x.

[kimswang]

if i was u i would put on a pair of 300x because the weight difference would be less by 200 pounds,more engines and more weight is more gas.the pair of 300x is more horsepower than the 3- 200 and u would be closer to 90mph.i have a friend with a 33 powerplay and his boat is better on fuel and is much faster than when it had on those 3- 200's.i have a 25 powerplay and i am putting on a pair of 300x.

Don't do it! Twins on a 25' is OK, but stay with triples on 30' +. Any given hull / weight combination need a certain amount of HP for any given speed. The increased efficiency with EFI will be most noticable at cruise and hardly noticable at WOT. If speed is what u want - go big 3x300, if economy is what u want - stay with what u got as the upgrade will never pay for itself unless you boat daily. I like both, and is taking my time going from twin 300 to triple MAD EFI V8's. So far it's been a ton of fun and I'm far from finished. Keep in mind the speed record for a CC is a fountain with 4x300xs and a speed of 87.6MPH. 90 MPH ain't easy anyway you do it....

[Pro300x24LD]

I know where you could get a 300x

[dkwestern]

Thanks for the replies guys. If I had a big fat wallet I would go with the trip 300's, but I have a line on 3 280's so that would be the reason for the 2.5's. I know I will never get my money back in fuel savigs, and that is not my goal, but I was figuring the EFI's would burn less fuel even though they make more power.

As far as the twin 300 setup, the boat would run 74-76 depending on 300/300x. And that would require a total re-rig, new throttles everything, so that option is out and would probably cost more than 3 new engines.

[dkwestern]

if i was u i would put on a pair of 300x because the weight difference would be less by 200 pounds,more engines and more weight is more gas.the pair of 300x is more horsepower than the 3- 200 and u would be closer to 90mph.i have a friend with a 33 powerplay and his boat is better on fuel and is much faster than when it had on those 3- 200's.i have a 25 powerplay and i am putting on a pair of 300x.

Which boat does your friend have? I remember the one that was a 1989-1990 or so that got re-rigged with 300's, do you have pics? Also the factory built 2 with twin 300's, a purple one and an orange one. ran 74 with 300's, and 76 with the 300x's.

[kimswang]

What kind of setback do you have? I am still rigging my Scarab, and still have a ton of fun doing it. Learning something new everytime I take it out. If you have any measurements with respect to setback, prop height with respect to bottom, how far apart your engines are and so forth it would be highly appreciated. Not too much knowledge / experience with triples out there...

[dkwestern]

I have 24 inches of setback on an armstrong bracket. I have CLE lowers that are exactly even with the bottom of the hull (propshaft) (X-dimension=0 I think?). I am not exactly sure how far apart each engine is but it is somewhere in the 22-26 inch range center to center, as long as the cowlings don't hit I would think the closer the better. Hope that helps, I also run 3 blade choppers for bow lift.

[kimswang]

Is your bottom 24 degrees V Bottom? Do you run 30" mid or 25"? What is the difference in height between the props? Yeah, yeah, I know.... tons of questions.. Don't feel bad if you don't have the answers, I am just trying to eliminate my trial and error time... Thanks for the response though...

[dkwestern]

My outside are 20" my middle is a 25" The middle engine is mounted 2" lower on the bracket, so it is 7" lower at the propshaft. 24 degree bottom. Hope that helps!! Good luck

[kimswang]

It sure does. I was about to extend my mid to a 30", but think that getting two new mids (20") would be better. Guess I have to start saving / looking again...

Thanks a million though, highly appreciate your input.

[brotherxb03]

I didn't think anybody with 3 outboards on a boat was too worried about gas mileage.

[kimswang]

I didn't think anybody with 3 outboards on a boat was too worried about gas mileage.

We are not too worried, we are triple worried....:D

[dkwestern]

Not worried about mileage, just curious.

No offense, But I laugh when I read on hear that guys bring 6 gallons of gas to the boat for the day. That is awesome!!! I think I go through that when I plane off. Have 200 gallon tanks so it is just a different perspective.

FYI - I measured and my centerline is 21" engine to engine. (skeg to skeg)

[1BadAction]

Have 200 gallon tanks

im sorry...