I think he’s saying he’s getting better mileage on 91.
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I think he’s saying he’s getting better mileage on 91.
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No I saved fuel on 91 not premium it’s a 115 Yamaha nearly 10 months old pushing 200 hours
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well there u go.. ive never extensively tested it.. of course all we have to go on is the fuel companys pushing it on us.. maybe in some cases some and i say some people get more on 98.. but thats awesome u get better fuel economy on 91.. as said i dont know enough to tell someone theres no benefit of 98.. but for the bloody price lol i am happy with the performance and cost of my 91 which i use on my car mower and boat.. and all my engines last a long time..Originally Posted by Jason Green
ill be somewhere up the creek, happy trails..
The benefit of higher octane fuel is its resistance to knock and ping nothing more, nothing less. My new 8hp yami 2 stroke manual says to use a min of 90 and if knocking and pinging occurs to use a different make of fuel or higher octane fuel.
The links I posted on the previous page also highlighted that synthetic fortified oils fall out of suspension when used premix in 91 octane fuels, but apparently no so with 95. No problem though if you don't use synthetic or synthetic blend 2 stroke oils.
And in relation to a previous comment - I'm not so sure drag cars run lean mixtures - top fuellers are on the verge of hydraulicing they run that much fuel through the engine.
There are many who run 91 and there are many who run 98 and everyone has some good and bad results.
I personally have a 2000 Model 115hp Johnson Oceanpro (2 stroke) and very happy with the use of 95.
There is mounds of literature for and against different fuels in different size outboards. I guess it’s what makes you happy that counts. Each to their own.
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thats it shakey use what makes you happy in life and if others dont agree/like it well just do it your way.. dont verbally beat some1 up,, if i had a bigger hp engine like you id use 95,, as for me a run a 9.9 so me 91 does the trick just sweet....
ill be somewhere up the creek, happy trails..
just a thought and could be wrong... but yamaha use 100/1 mix tohatsu and mecury 50/1 ... i dont care what motor i run i always go 50/1 (back of hippies or ill turn ya power off if i cant have me 50/1 lol) so the point is just cos yammie says there engine can handle 100/1 ive always run smaller engines on no less then 50/1.. maybe if its knocking and pinging uping the 50/1 mix may help... as said could be wrong but my motors on 91octane and 50/1 have never knocked or pinged,, just a thought to throw into the mix.
ill be somewhere up the creek, happy trails..
98 over 91 is 15-20% more here in the bush you are not going to save that same percentage in fuel use between the two
98 has cleaning detergents added its probably just giving a dirty engine and carb a clean
too small a sample size
could have just been other factors on the day
bimini up and down
wind behind you
flat surface v small ripples
Hi stevej if you’re talking about my comment conditions have been the same as usual if not worse on the last few trips I have done and it’s still saying my fuel economy is running better on 91 I don’t know why but anyway it is
Usual day trip is 150-200 km
Roof doesn’t change bit hard folding it down and driving
Weight is usual except the last couple of trips heading out into 10-15 knot northlies with 4 foot swells at 4 seconds on a outgoing tide which is not real comfortable at the top end of Hervey Bay but I have been locking the ballast tank off keeping 150litres of water on for extra weight for the trip out which makes a big difference in comfort but does burn the fuel
I don’t know why it is doing better but anyway it’s saving me a bit on fuel money for more beer
When I get decent conditions to open her up next I guess I will be able to see whether there are any changes at wot
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Jason wasn't aware of the large trips you were doing, any dollar saved is a bonus
I haven't checked in for a while so I just noticed the critique of my post.Thanks for confirming my admission of limited fuel science knowledge and possibly you could clear up all the other inaccuracies in my post for me so that next time someone asks for thoughts I won't make the same mistakes.
this is my experience. Putting 98 instead of 91 does no harm to motor. Putting 98 in costs more, gives a slight boost to the performance does increas range slightly. No where near 10% improvements. On a cost basis, pay more go further, its a zero sum gain. Now if your motor is tuned to run 98, you would be crazy not to take advantage and. 10% gain has been factored in by design. Does 98 go off faster than 91? No idea but i have never experienced bad fuel either.
my take is that its just not worth it long term. Short term, hey it doesnt hurt and may clean up the insides a bit.
Agree.
I reckon I got around 10% more range on every modern motorcycle I have owned and done the standard commute day after day. The XR had something like a 9 litre tank so I really noticed it there. Boats - dunno...probs not.
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The higher octane fuels are more refined and have more stable hydrocarbons resulting in the ability to reduce octane loss and vapor pressure loss over a longer period of time. There is one answer to this conundrum, if you use your boat frequently 91 is OK, but if stored for any period then a higher octane would be preferable. Most motors benefit from going up to the next octane level but generally no further and would be considered a waste of money. There is also other factors involved but it starts to get complicated especially if you start comparing carby 2 strokes vs 4 strokes and even newer 4 strokes vs some old ones.
Best way is to test for your selves and be happy with your decision. I know of people where the pennies are tight and will always go the cheapest (except E10) and that is fine with me, others have done some research and have their opinion, fine with me also. I use 95 after talking with mechanics, both car and outboard, a mate who works in the fuel industry and another who is an industrial chemist so I am happy with my decision. ☺
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