High test gasoline shows increase performance

[pecheux]

Re: High test gasoline shows increase performance

Ok fellow I know you all read enough about gasoline, but I have to add this latest test and state my case ... LOL since a few posts raised my curiosity one more notch.

Today took the small boat (avatar) out again, same river, same wife aboard, same beer & sodas cooler, but this time using my 1981 Johnson 9.9 hp. and using a new fresh tank of gas using PREMIUM 91 octane with synthetic oil.

I use this motor a few times a year only for trolling purpose. I was simply amased at the extra push power it had, even my wife who knows nothing about motors noticed. Now I am not saying Way more power ... but some, enough to feel the difference.

Next time I m trying this 94 octane premium available at a close by gas station. But I wrote enough already and will keep the result to myself. LOL LOL

Cheers

 

[ondarvr]

Re: High test gasoline shows increase performance

The thread was entirely about 2 strokes 15 HP engine, this statement can be applied to new 2 strokes also. Computarized outboards are completely different animals. Been reading that E fuels lowers octane ratings by 2, so a 87 could be really a 85 and so on. That's why using higher octane fuel would be advisable, and besides, higher octane have better cleaning aditives than lower octane fuels, will keep pistons, plugs much cleaner in case you don't use periodically carbon guard or products that mixes on tanks.

Happy Boating

Maybe these things are true in Peru, but here in North America 87 octane is is 87 octane, it makes no difference if it's E-10 or E-0.

also, by law all grades of gas have the same ingredients, the only difference is octane rating.

 

[ondarvr]

Re: High test gasoline shows increase performance

Begging the question abounds.

The fixed timing might be set such that the whole system operates better on higher octane fuel. Unfortunately, that's the reality against your argument.

I am not saying the OP got results from the octane change; I am saying that in an older non-EFI engine, you can bet your hat that there are going to be engines that benefit from higher octane, because they are going to work better with the timing.

It's also possible I will win the lottery this week, but the odds are slim.

The manual will state what it needs, running a higher octane is just a waste of money. People can buy the higher octane stuff and think the motor runs better and faster, and if it works for them...great.

 

[tomstehr]

Re: High test gasoline shows increase performance

The octane rating you see at the pump is a formula of two different test used to dermine octane rating on fuel and is actually the Anti Knock Index number. The higher the number, the more resistant to explosion the fuel is when compressed. According to research, an Anti Knock Index of 67 is sufficient for typical two stroke engines. If your motor runs that much better on higher octane fuel, then perhaps a timing adjustment will make it run just as well on regular? I think Canada and the US use the same RON+MON / 2 formula on the pump for labeling and that is the formula Research Octane Number + Motor Octane Number / 2 = AKI ,or pump labeled octane rating.

 

[5150abf]

Re: High test gasoline shows increase performance

At least he didn't call it Ethyl.

I am of the camp that gas is gas and one test has no more "power" in it than any other, the only thing that changed is resistance to preignition.

I always run 81 in mine and it runs slighty different every time I go out, same strecth of river, same boat but some trips I get 26mph sometimes 29-30, current, temp and humidity are the only differences.

 

[pecheux]

Re: High test gasoline shows increase performance

At least he didn't call it Ethyl.

I am of the camp that gas is gas and one test has no more "power" in it than any other, the only thing that changed is resistance to preignition.

I always run 81 in mine and it runs slighty different every time I go out, same strecth of river, same boat but some trips I get 26mph sometimes 29-30, current, temp and humidity are the only differences.

I am not turning my back on your opinion and I would rather switch than fight (lol cigarette add) One factor that I forgot to mention is that Premium gasoline at our local Ultramar gas station says clearly on the pump "Ethanol free" and I wonder if that would not be the reason for the differece I withness ??

They have a discount on that Premium every tursday, same price as Medium range (but higher than Regular), and you have to wait in-line to get to the pump, so I guess I am not the only one that like this particular gasoline. Happy boating.

 

[foodfisher]

Re: High test gasoline shows increase performance

That, sir, is a game changer.

 

[ondarvr]

Re: High test gasoline shows increase performance

One factor that I forgot to mention is that Premium gasoline at our local Ultramar gas station says clearly on the pump "Ethanol free" and I wonder if that would not be the reason for the differece I withness ?? Happy boating.

Now there is a possible real reason for a difference in performance. As I said earlier in this thread, ethanol content will affect HP, possibly enough for you feel with the motor you have, octane...not so much.

 

[ampcarfan]

Re: High test gasoline shows increase performance

I'll jump in. Ethanol has an octane rating of around 100. I'm sure the oil companies take this into consideration when blending with gasoline. It seems to me they would be able to blend it with a lower octane gas to achieve the overall desired octane rating... win, win again for them. Some here are right, without the benefit of electronic variable ignition timing and knock sensors, the use of high octane fuel on a stock engine with a oem 87 octane rating would see no benefit to the use of "premium". However, if a combustion chamber was carboned up enough to create a higher compression ratio, then "some" may notice an increase in performance with the use of higher octane fuel. my 2 cents

 

[jmerc650]

Re: High test gasoline shows increase performance

Things are getting mixed and confused.

Your SUV has fuel injection and a computer to adjust the settings and take advantage of higher octane fuels, it in no way equates to increased performance in an old school O/B.

Merc and a few other outboard manufactures have specific motors that should run higher octane fuel and it says so in the manual, the vast majority of motors are designed to use the cheap stuff though, just check your manual.

In some parts of the world you can't always trust the fuel being supplied is all it should be, so maybe running a higher octane is good insurance if the quality is in doubt.

The facts are your typical old school outboard is not going run better or make more power with a higher octane gas than it was designed to use.

a dyno test on my merc 650 says otherwise. bone stock tuned engine. on regular, the wot HP is 69.31 hp at 5296 rpm. on super the wot HP is 72.12 hp at 5423 rpm. both test were performed four times each alternating reg, sup, reg, sup, reg, sup, reg, sup with identical conditions on each test, 26% hm at 72? and water temp of 84?. just un able to measure speed on the dyno. but rpm increase is a speed increase

 

[ondarvr]

Re: High test gasoline shows increase performance

If you notice I mentioned Merc in my responce, they tend to be tuned for higher performance.

 

[Silvertip]

Re: High test gasoline shows increase performance

Thank you for your support ...LOL Actualy 10 years ago an old friend who was an Ex Mercury dealer, and who was also my outboard motor mecanic, told me I should use 91 octane (hightest) gasoline at all times. According to him gasoline's quality was on a downward trend. Now just 2 weeks ago the senior mecanic from our local and major Mercury dealership told me the exact same thing.

Furthermore my 4 cyl SUV that should use 87 octane fuel happens to run better and show bigger horses when fueled by 91 or 94 octane fuel. Now what is the old saying ??? no smoke without a fire ??? or something like that .. LOL Cheers

You are obviously ignoring the fact that your SUB has a knock sensor and that the ECU can adjust the ignition timing automatically just short of the pont of detonation -- and it does it in a heartbeat With higher octane fuel the timing advances further and hence more power. I do not buy the better performance from premium fuel in an outboard with a standard ignition system. If that outboard was last tuned so the timing favored premium fuel then one could expect better performance. But if that's the case, then the engine is tuned incorrectly for regular grade fuel and you could risk detonation. Without a tach and without a gps I simply don't buy a "significant" performance increase by chaning grade of fuel -- especially if the engine is tuned for regular and that's what the manufacturer recommends.

 

[pecheux]

Re: High test gasoline shows increase performance

You are obviously ignoring the fact that your SUB has a knock sensor and that the ECU can adjust the ignition timing automatically just short of the pont of detonation -- and it does it in a heartbeat With higher octane fuel the timing advances further and hence more power. I do not buy the better performance from premium fuel in an outboard with a standard ignition system. If that outboard was last tuned so the timing favored premium fuel then one could expect better performance. But if that's the case, then the engine is tuned incorrectly for regular grade fuel and you could risk detonation. Without a tach and without a gps I simply don't buy a "significant" performance increase by chaning grade of fuel -- especially if the engine is tuned for regular and that's what the manufacturer recommends.

It's a 1981 Johnson 9.9 hp. Bought new, it never went back to the dealer, no repairs, low hours, I only change gear oil and new plugs every other years. Maybe gasoline was better back then ... and it remembers ... LOL cheers.

 

[Sea Rider]

Re: High test gasoline shows increase performance

Most 2 stroke Tohatsu, Yamaha, Evinrude manuals from engines that have owned says about fuels : unleaded minimum pump posted 87 posted is recommended (91 octane based in research octane rating method) including the use of higher octane. Yesterday made a experiment on a rowing watercourse: ext temp 24? C, water temp 17?C, Tohatsu 2 strokes 18 HP mounted on a 420 sib, total weight, passenger/boat/engine 300 KG on a 1 Kilometer wot staright course. All our fuels are rated what stated at each pump.

2 independent fuel tanks, 90 & 95, with 50:1 fuel/oil ratio
90 octane fuel 37.3 Km/H
95 octane fuel 39.9 Km/H

Even the sound of the engine changed, you coul feel the engine response difference while slight throttling , to maintain plane needed less throttle than runing with 90, if it works well for me will continue to use higher octane gasolines. Don't like the idea of saving some cents buying lower octane fuels and needing to refuel at a faster rate because of faster consumption with least performance, a very stupid form of saving and in the process cheating yourself issue.

The posters will need to experiment if on their particular engines this octane issue works or not for them. By the moment will stick with Pecheus, JMerk650, Sea Rider's musketeers motto ; one for all, all for one...

Happy Boating

 

[pecheux]

Re: High test gasoline shows increase performance

Most 2 stroke Tohatsu, Yamaha, Evinrude manuals from engines that have owned says about fuels : unleaded minimum pump posted 87 posted is recommended (91 octane based in research octane rating method) including the use of higher octane. Yesterday made a experiment on a rowing watercourse: ext temp 24? C, water temp 17?C, Tohatsu 2 strokes 18 HP mounted on a 420 sib, total weight, passenger/boat/engine 300 KG on a 1 Kilometer wot staright course. All our fuels are rated what stated at each pump.

2 independent fuel tanks, 90 & 95, with 50:1 fuel/oil ratio
90 octane fuel 37.3 Km/H
95 octane fuel 39.9 Km/H

Even the sound of the engine changed, you coul feel the engine response difference while slight throttling , to maintain plane needed less throttle than runing with 90, if it works well for me will continue to use higher octane gasolines. Don't like the idea of saving some cents buying lower octane fuels and needing to refuel at a faster rate because of faster consumption with least performance, a very stupid form of saving and in the process cheating yourself issue.

The posters will need to experiment if on their particular engines this octane issue works or not for them. By the moment will stick with Pecheus, JMerk650, Sea Rider's musketeers motto ; one for all, all for one...

Happy Boating

Support at last ... LOL LOL Cheers

 

[ondarvr]

Re: High test gasoline shows increase performance

Most 2 stroke Tohatsu, Yamaha, Evinrude manuals from engines that have owned says about fuels : unleaded minimum pump posted 87 posted is recommended (91 octane based in research octane rating method) including the use of higher octane. Yesterday made a experiment on a rowing watercourse: ext temp 24? C, water temp 17?C, Tohatsu 2 strokes 18 HP mounted on a 420 sib, total weight, passenger/boat/engine 300 KG on a 1 Kilometer wot staright course. All our fuels are rated what stated at each pump.

2 independent fuel tanks, 90 & 95, with 50:1 fuel/oil ratio
90 octane fuel 37.3 Km/H
95 octane fuel 39.9 Km/H

Even the sound of the engine changed, you coul feel the engine response difference while slight throttling , to maintain plane needed less throttle than runing with 90, if it works well for me will continue to use higher octane gasolines. Don't like the idea of saving some cents buying lower octane fuels and needing to refuel at a faster rate because of faster consumption with least performance, a very stupid form of saving and in the process cheating yourself issue.

The posters will need to experiment if on their particular engines this octane issue works or not for them. By the moment will stick with Pecheus, JMerk650, Sea Rider's musketeers motto ; one for all, all for one...

Happy Boating

Again...What is the the ethanol content of each grade, less E = more HP. The only way to know is to test it yourself, what's printed on the pump only says "may contain up to 10%" not what it really is.