4 Stroke Nissan 9.8hp Gas Consumption

[Super]

I have a 14’ open aluminum boat with a 1974 Evinrude 9.9hp 2 stroke outboard. I can do about 14mph if it’s just me on the boat. My 3 gallon tank takes me about 12 miles before I’m empty. That’s 4mpg.

The new Nissan 4 stroke 9.8hp outboards claim to use 1 gallon an hour. That would translate into 14mpg on my boat.

Are the 4 strokes really getting that much better mpg’s? 4mpg vs 14mpg is a big jump.

[Gerry Zagorski]

Need more information on your statement "1 gallon per hour". Is that at idle, running RPM or what?

In any event, I would doubt very much that you are going to go from 4 miles to 14 miles per gallon. 4 stroke vs 2 stroke is likely to get you 20 -30 % better but that's about it.

At idle is a much different ball game as 4 stokes are much more efficent at idle then 2 strokes.

[Capt. Debbie]

I have a very loaded alum 14' Mirrocraft with a 25hp EFI 4 stroke. I run a 12 gallon tank ( in bow to counter my fat butt in stern) for more than half dozen trips from Rumson Ramp west to the Front Street Bridge in Red Bank. That's 4 nautical miles as crow flies each way. Or a little over 4 nautical mpg's running near WOT making about 21-22k.

I can see you getting maybe hi 6 mpg or even 7 mpg at planing speed range.

But a 9.9 14mpg even idling along on a 6' inflatable seems optimistic.

[Super]

Thanks for the reply.

I also have a Mirrocraft, but I don't load it down too bad.

Nissan claims 1GPH @ 5500rpm.

http://www.nissanmarine.com/tech_talk/gas_mileage.html

New Nissan 2 strokes use 1.3GPH, so I guess that somewhat answers my question. Except now I'm not sure if my old 1974 Evinrude is a gas guzzler.