7.4 MPI vs 5.7 EFI, on a 260 Sundancer, gives the best mpg

[hakon]

Hello!

I want to import a 260 DA to Norway, and the fuel price in Norway is very very high. $6 for a gallon.

So I need the engine that will give the best milage on a gallon.

Is it true that a 7.4 will use less fuen then 5.7, because of lower rpm on cruising speed?

What kind off engine will you recomand?

Thanks hakon

 

[skolbe]

Mine with a 7.4 MPI with a Bravo III got 2.25 MPG on long cruises. It loved to cruise at 3200 RPM's which was around 29 MPH.

 

[wickeral]

I'd go with the 7.4! I have one with a Bravo III pushing a 250 Sundancer. Very thrifty and lots of go. It's propped to cruise. Al W.

 

[dpmulvey]

Tough question. Stress comes from noise and vibration. The 7.4 may or may not be as economical. It will however attain the same speed at a lower RPM and depending on how the boat is insulated, most likely at lower noise from the engine compartment. It may be a trade off worth the cost.

 

[Stray Cat]

Your first post....Welcome to the board!

My 310 hp 7.4 MPI / BIII consistantly averaged 2.0 mpg, on a 6500 lb 270DA. The newer 5.7 (350 Magnum) is published at 300 In my opinioin, the 7.4 is a torque monster compared to the 5.7....

Curious...Why import a US boat vs. seeking one in your area?

 

[Aarrhh & Aarrhh]

I have the 5.7 in my 260. At cruise I see 12-13 gph burn rate. I haven't worked out the MPG yet.

 

[dpmulvey]

Hello!

I want to import a 260 DA to Norway, and the fuel price in Norway is very very high. $6 for a gallon.

So I need the engine that will give the best milage on a gallon.

Is it true that a 7.4 will use less fuen then 5.7, because of lower rpm on cruising speed?

What kind off engine will you recomand?

Thanks hakon

If it is a new boat, you will not get the 7.4. Merc does not offer it anymore. If you are ordering a European version, your options are limited to a 6.2L, 8.1L or diesel. The diesel will not be as fast, but will average 3-4 MPG (a Regal owner on the former Regal site had a diesel on his 2465). The 8.1 will run at the same speed as a 260 equipped with a 6.2 albeit at a lower RPM and hence quieter (see my previous post). That does not necessarily mean lower fuel consumption however as the 8.1 is several hundred pounds heavier than a 6.2. In theory, one would think the lower RPM would yield a better fuel economy at cruise, however, modern engines are made to run at a higher RPM Cruise than their predecessors and burn less fuel doing so. Makes no sense to me but that is the way it is. Additionally, a lower than optimum cruise RPM may not necessarily be good for the engine's longevity. I am sure there are some engineers here who could chime in on that aspect.

The question being begged is for those who have the boat you want post actual GPH figures for their boats.

HTH