Test done of RPM vs MPH vs MPG on CD25 with a Honda BF150

S

smckean (Tosca)

New member
I just had the Honda BF150 tuned up (major tune) on my CD25 Cruiser; so I did this test. Thought I would post it here just in case it is useful to someone. The numbers seemed in keeping with factory specs, my expectations, and the previous owner's experience.

GPH were determined via a NavMan. MPH via a speedo (which tends to read 2 MPH low at slower speeds -- the numbers reported here are uncorrected for this). MPG were calculated. Everything is statute miles.

4/8/15: testing with S3x14.5x15R prop on nearly flat water with 1 person; medium loaded; <1/2 tank gas; full tank water

RPM MPH GPH MPG
- 1000 2.3 0.1 n/a
- 1500 4.0 0.6 6.7
- 2000 5.2 - 5.4 0.9 5.9
- 2500 6.3 - 6.6 2.0 3.3
- 3000 9.7 - 10.0 4.5 2.2
- 3500 12.8 - 13.1 4.6 2.8
- 4000 17.8 - 18.1 6.5 2.8
- 4500 23.0 7.7 3.0
- 5000 28.0 9.5 2.9
- 5600 32.0 ? ? (this was WOT)
 
Good data. That's just about exactly what I get with my twin Yamaha 80's. I tend to cruise between 15-18 nmph and average 2.5-2.8 nmpg depending on loading and sea conditions. This has been pretty consistent over the 12 years I've had the boat.

Thanks!
 
Here's some mileage/speed/rpm figures done a couple of years ago. I'd bet the difference is the loading of the boats. Clost to your figures, pre ethanol.

Daydream and Anna Marie

Mileage
C_25_MPG_0.jpg

MPH (NOT KPH)

C_25_RPM_0.jpg

Boris
 
And here's Tosce. I feel that performance is best seen as a graph.

Speed
Tosce_RPM_MPg.jpg

Mileage
Tosce_RPM_MPH.jpg

I'd have liked to overlay these data, but I've lost the original data.

Boris
 
Very cool.....thanks, journey on.

Not sure why I didn't think of doing that. I certainly will from now on. I'm doing a series of these tests using the 2 props that I have to see differences. I also want to see how these numbers change with loading. I'm doing it now because the engine just got a major maintenance so I figure it's running about as efficiently as it ever will. (BTW, the tune up definitely has increased the boat's performance.)
 
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