cruising rpm's & gph 2000

This has come up a few times before. Someone had a chart on this. J Levine? Frank C? The fuel burn #s for each 7.4 340hp are identical at each RPM regardless of the boat they're in. Your speed will vary, because of boat size/weight/hull design. If you're 340HP, than you are carbuerated, right? Those numbers would be different from the MPI version, which I think make 370HP. In a nutshell, I can't answer - I have observational numbers for my boat using floscans - but someone will see this and have the actual graph for the engine on a dyno.

I don't recall ever seeing boat specific numbers published. But you can easily do the math if you have the dyno data and your speed over ground at each RPM interval. You can then formulate your optimal cruising economy, which will PROBABLY be around 3200RPM, burning about 32GPH and get you moving at around 24MPH. That keeps you out of the secondary carb barrels and gets you about 0.75MPG. It aint no Prius but pretty good for a gasser that size and weight.
 
Last edited:
Apples and oranges. That's a 8.1L MAG Horizon. Completely different engine that what Hoo'sdave has.
 
rondds said:
This has come up a few times before. Someone had a chart on this. J Levine? Frank C? The fuel burn #s for each 7.4 340hp are identical at each RPM regardless of the boat they're in. Your speed will vary, because of boat size/weight/hull design. If you're 340HP, than you are carburetor, right? Those numbers would be different from the MPI version, which I think make 370HP. In a nutshell, I can't answer - I have observational numbers for my boat using floscans - but someone will see this and have the actual graph for the engine on a dyno.

I don't recall ever seeing boat specific numbers published. But you can easily do the math if you have the dyno data and your speed over ground at each RPM interval. You can then formulate your optimal cruising economy, which will PROBABLY be around 3200RPM, burning about 32GPH and get you moving at around 24MPH. That keeps you out of the secondary carb barrels and gets you about 0.75MPG. It aint no Prius but pretty good for a gasser that size and weight.
Click to expand...
7.4 310HP no carburetor
 
MPI? are you sure? I thought the FI models were more than 340HP?? ANYONE???
 
We own a 2001 340 with 7.4s and v-drives. We ran an 829-mile cruise in 7 days. We burned 1128 gallons. We had one portion of the trip in which we ran 150 miles against the current of a swollen river. Other conditions were we ran a little heavier than normal. We kept a full water tank. Six full 5-gallon cans spare gasoline. Supplies for the seven-day cruise. When heavy we ran 3600 RPM at about 26 MPH (21 up the swollen river). When light we ran 3500 for the same speed. Total run time was 49.5 hours, of course not all at cruise Average .74 miles per gallon. Average about 23 gallons per hour.
 
You must log in or register to reply here.

Forum statistics

Threads
113,253
Messages
1,429,373
Members
61,133
Latest member
Willbeckett
Back
Top