Fuel Consumption on Old Johnson 30HP

[ByteWalker]

Hi,<br />You've all been so helpful, I first want to thank you very much. Now for the question:<br /><br />1956 Johnson 30HP RJE-18 - Approximately what is the fuel consumption per hour for this type of motor. I bought the boat in '95 but didn't use it. I have more experience with diesel motors and need to plan on how much fuel I should carry when I go on the lake with the boat. I have several gas cans of all sizes from when I lived on my sailboat.<br /><br />Thanks again

 

[nordy]

Re: Fuel Consumption on Old Johnson 30HP

Hi Bytewalker,<br /><br />I've got a 2000 Johnson 30hp.<br />The average consumption is about 5 l/h in the following driving situation:<br />50% speed around 35km/h, 30% 20-25km/h and 20 % around 10km/h.<br />The boat is a Zodiac 4,20m, driving weight around 500kg (1103lbs).<br />With maximum speed consumption will exceed 10 l/h.<br /><br />Greetings from Germany<br /><br />Nordy

 

[rolmops]

Re: Fuel Consumption on Old Johnson 30HP

Hello again Suzie.<br />With that little boat of yours you can probably do 2 miles per gallon maybe a bit more.Never go out with less than a full six gallon tank.<br />Enjoy.

 

[Lark40]

Re: Fuel Consumption on Old Johnson 30HP

All of the old "Big Twin" series of engines were thirsty. If you have two six gallon tanks, just keep the second one aboard for your first couple of trips, until you have a feel for distance and consumption.

 

[Hooty]

Re: Fuel Consumption on Old Johnson 30HP

A rule of thumb is 10% of the rated horsepower per hour at wfo. In other words, 10% of 30hp. is 3, so the fuel consumption would be 3gph at full throttle. You'll also find that the fuel consumption at 3/4 throttle drops to 1/2 or less then that 3 gph. Again, this is all approximate.<br /><br />c/6<br /><br />Hooty

 

[Paul Moir]

Re: Fuel Consumption on Old Johnson 30HP

The later 28hp (same displacement, etc) has a claimed consumption of 'almost three hours of cruising off a 5 gallon tank', which would be around 2 gph. I think that agrees with Hooty's rule of thumb. My one has been .6 pounds of gas per hour per horsepower, which is the same thing...

 

[ByteWalker]

Re: Fuel Consumption on Old Johnson 30HP

Thanks Everybody... I'll do the 2 six-gallons when I go out. Back in 1956 when the motor was new, I think gas was about 20 cents a gallon but then wages weren't what they are today!<br />I only drive a "land-vehicle" about 5,000 miles per year, so you can tell where I would rather spend my time, just haven't done it lately since moving off my sailboat! My little 3HP Johnson was on my dinghy, but I only used it to go to and from shore. I had a 15HP on my "dive-boat" that was 15' 11".... 8' beam. Really was a 'platform' for personal scuba trips... (that was in the Hawaiian Islands). If anybody wants any info on taking a trip to Hawaii, write me and I'll be glad to tell you why you should spend your money to go elsewhere! (Spent 5 years in the islands). <br /><br />I'm also looking for a forum for British Seagulls.... anybody know of any? I have 2 that I am going to hopefully re-build. They sure are noisy, but they're powerful for their size. Lots of torque. Good for kickers and dinghy's.