fuel consumption

[mr angry]

I know a v6 175 outboard will be far from economical to run but was shocked when it used 25litres of fuel in 20 minutes. Is this normal or is there anything I should be looking at apart from a smaller outboard?

 

[jorgens98]

Re: fuel consumption

I know a v6 175 outboard will be far from economical to run but was shocked when it used 25litres of fuel in 20 minutes. Is this normal or is there anything I should be looking at apart from a smaller outboard?

Boat size?
Speed?
Wind?
Current?

JJ

 

[sourbsted]

Re: fuel consumption

I have 150hp inline 6 merc.. wont use that much that quickly! :^

 

[EFI]

Re: fuel consumption

a outboard will use ' One gallon per hour, per ten horsepwer..wide open ,
175 horsepower = 17.5 gallons per hour.
convert to litres ..doesnt sound too bad

that is rule of thumb.. boat size, prop , wind will all play into that

 

[Texasmark]

Re: fuel consumption

I used to run crossflow charged 2 cycle outboards. Don't have the numbers but with a 35 hp (in the late '50's) you could go through two 6 gallon cans of gas on a Sunday afternoon outing with the boat beached most of the time.

In later years, My 125 OMC crossflow would empty an 18 gallon tank with us doing a lot of swimming around the boat, not running it.

Bought a Direct Charged tower @ 115 hp and could go all day on a 10 gallon tank and come home with fuel.

Direct charge was a ported piston, like loopers, but not exactly, and a couple of other refinements. OMC still had the patent on loopers when Merc tried to compete......and did a pretty good job.

Have a 90 3 cyl looper now and can go fishing on 3-5 gallons and I do a lot of just playing, not much fishing.

I would compare loopers to a poorly tuned 4 cycle having had a 4 cycle 120 Mercruiser.

Don't know what kind of lift you get with the new technologies in engines (EFI, etc), but baby, it's sooooooo much better than it was.

As far as buying a 4 cy just on fuel consumption alone, I'd say forget it. My opinion.

Mark

 

[mr angry]

Re: fuel consumption

The engine is a mariner 175 v6 and it is on a zodiac 6metre rib with 3 people unladen, no wind flat conditions on fresh water with a 18 pitch plastic prop at about 45 mph (not quite full throttle approx 5000 rpm)

 

[canadian_fisher]

Re: fuel consumption

Mr Angry.

I had a V6-150 Crossflow in the spring.
It would gobble up 15 gallons an hour or about 60 Litres at WOT around 50 MPH @ 5500RPM.
I would guess your 175HP V6 is around that mark.
So, 25 Liters in 20 minutes = 75 Liters / hour = 17 Gallons /hour.
Math is almost dead-on for a 175 HP.
I recommend you drive from Marina to Marina 8)

Good Luck....... CF

 

[Silvertip]

Re: fuel consumption

Or cut back to 3/4 throttle and save a little fuel at only slightly slower speed. That last 5 - 10 MPH uses lots of fuel.

 

[gss036]

Re: fuel consumption

I would suggest that you change your prop to alum or stainless. You have to be lossing a lot of power to the plastic prop slipping/flexing real bad. As the above post suggest, cut back to 3/4 throttle and save 4-5 gallon per hour. I don't see the need to go 50 mph. You would not do that in our water here. Too many logs and crab pots and gobs of ell grass/kelp.

 

[jorgens98]

Re: fuel consumption

Run it at 4000 rpms - the last 1000 costs incredible. And you dont get the equivalent in speed.


JJ

 

[Texasmark]

Re: fuel consumption

Merc used to have what they called "back drag" on the throttle setting. My tower had it I think. What they did with the engine was to increase spark timing as a function of throttle setting (guess everyone does this part) so that at WOT you were running max spark advance.

But the way back drag worked was for you to go to the WOT position on the throttle and then pull it back (to 4000 or wherever) and the spark would stay advanced.....don't know where it started to come off max. This allowed you to run leaner and cheaper.

Must have worked cause that engine had incredible efficiency for not being loop charged. Had a lot of low end torque....just a sweet engine....I loved it......sold it to my son-in-law who still has it....was an '89.......hell I'm going to start crying. Grin

Mark

 

[northvanwatertaxi]

Re: fuel consumption

are you kidding?
serious?
really?
I have a v8 ford 302 and would never ever run it fast
just get the boat up on a plane and throttle back a bit untill it's
just purring along on plane and you will go very far
where is the fire?

 

[Texasmark]

Re: fuel consumption

Don't know who you are addressing North, but if it's me my answer is the absolute truth. I mean it. The Direct Charge tower was my first non-crossflow and I couldn't believe the difference in fuel consumption. I'm running a little 90 hp 3 cyl looper now and it is incredible how fuel efficient it is.

Now I will say this. These engines are/were on padded boats so when you get them up and going, there isn't much wetted surface to gobble up hp and fuel so that has to be part of the equation too.

Mark

 

[deejaycee_2000]

Re: fuel consumption

Sounds fine to me, I also use about 25 litres in half an hour of wakeboarding .... 115hp suzuki ....

 

[Texasmark]

Re: fuel consumption

Was reading some old OMC brochures from the '60's and seems they had it too.....but didn't call it back drag.

Mark