Premium Fuel ?

[Ron173]

Hi,<br /><br />I live in Australia and have had a few high powered motorcycles, I ran these on PULP, (premium unleaded petrol) and found that despite the extra cost, you got a bit more grunt and slightly better fuel economy.<br /><br />Would this apply to a 2 stroke outboard??<br /><br />Any views / opinions appreciated<br /><br />Ron

 

[05GlastronSX]

Re: Premium Fuel ?

people always say run what your engine was designed to run on. if it wasnt designed only for high octane fuel, to me, theres no need for you to use it, its just extra money out of your pocket. all higher octane does is increase the engines resistance to knocking. if your engine performs well and does not knock, there is no need for higher ocatne fuel. Also, the more expensive gas sits in the holding tanks for longer periods of time and is not as fresh as the cheaper gas that is being used quicker by more people.

 

[ZmOz]

Re: Premium Fuel ?

Yes, anything over what your motor was designed to run on (probably regular) is a 100% waste of money. This goes for any internal combustion engine...

 

[pwiseman]

Re: Premium Fuel ?

One reason to run premium that makes sense is to get away from alcohol blending. Some states require a percentage of ethanol, which can cause problems for some motors. There is a provision in my state that allows off road vehicles to use non-oxygenated gas, so it is available in some locations, but generally it is premium grade only. My current motor manual says it requires 87 octane and 10% ethanol is ok, but straght gas is better.

 

[05GlastronSX]

Re: Premium Fuel ?

here in wisconsin, there is only reformuated gas(gas with ethonal) in major cities like milwaukee, but anywhere else outside of milwaukee is non reformulated with no additives.

 

[bernieb]

Re: Premium Fuel ?

What about e85 gas (85% ethanol) 15% gas ,does anybody use this in any outboard ? I'm hearing up to 50% cheaper on this gas.

 

[walleyehed]

Re: Premium Fuel ?

50%????maybe....If you run your outboard on E85, plan on buying a new outboard next year....

 

[Joey One]

Re: Premium Fuel ?

Regular gasoline is more volatile than premium; that's why it pings in high compression engines. So if you don't have a pre-ignition problem, use regular. Starting is easier on regular.<br />I think the manufacturer's restriction on ethenol is to prevent damage to synthetic gasgets in the fuel system. During WW-II, we burned anything that even smelled like fuel(paint thinner, alcahol, kerosene).<br />We used rationed gasoline for starting fluid. But then, gasgets were made of paper, asbestos, cork,<br />or leather. I guess the alcahol didn't disolve these materials.

 

[05GlastronSX]

Re: Premium Fuel ?

i will not fill up either of my boats down in any major city due to their reformulated gas. i will only put the strait gas with no additives in, and plus, its actually cheaper than city gas. Also, my engines seem to run much better with the non refomulated gas...

 

[pwiseman]

Re: Premium Fuel ?

Originally posted by bernieb:<br /> What about e85 gas (85% ethanol) 15% gas ,does anybody use this in any outboard ? I'm hearing up to 50% cheaper on this gas.

Politicians will spew anything to get an agenda passed. This E85 might be a good thing at some point, but right now it is a problem for most engines. Most of the newer outboard manuals that I have read say no more than 10% ethanol or 5% methanol. Ford came out with some car engines designed for E85 or regular gas a few years back. Have not heard much about this of late since most of the focus seems to be on hybrids at the moment.<br /><br />I am waiting for the F-350 Hybrid myself. I don't want a stinking prius.

 

[monkeyboi]

Re: Premium Fuel ?

i've read elsewhere in the forums that the higher octane burns at a hotter temp as well. do a search on 'premium gas' or something similar. the consensus seemed to be whatever the manufacturer recommends

 

[Bwalker]

Re: Premium Fuel ?

"higher octane burns at a hotter temp "<br />Who ever spewed that little tid bit does not know what he is talking about. ALL gasoline regardless of octane has about the the same BTU per gallon. Its also a common misconception that higher octane fuel burns slower, cooler and is less volitile. All of these are false. Higher octane fuel simply resists abnormal combustion(pre ignition,detonation) better than lower octane fuel. In a nutshellhigh octane fuel is less pressure sensitive.

 

[Dhadley]

Re: Premium Fuel ?

The old leaded hi octane did burn cooler. Todays hi test actually creates a higher combustion temp in stock, as produced recreational 2 stroke outboards. Just run any stock recreational outboard motor with an EGT gauge and switch back and forth between 87 and 93.

 

[Bwalker]

Re: Premium Fuel ?

"Todays hi test actually creates a higher combustion temp in stock,"<br />I dont buy that. I have done a bunch of testing with various two cycle motos and have never noticed a temp increase with premium. Could one fuel be RFG and the other not?<br /> BTW where are you hooking up the EGT gauge on a outboard? I have used EGT for years as a tool in tuning snowmobiles.

 

[walleyehed]

Re: Premium Fuel ?

Ben, before you get completely frizzed, Dhadley has not only raced profesionally for many years, he has been involved in the develpement of some of the engines we run today in the outboard industry and many of the rotating mass components...listen to his advice, you can't "Buy" the kind of knowledge he shares with us...<br />The EGT probe is very easily installed in the aft section of the exhaust chamber..

 

[Dhadley]

Re: Premium Fuel ?

On the dyno motors there's a probe on each cylinder. On the boat with V6's we put one probe in the adaptor plate in each exhaust chamber. On a V4 we use one probe since there's a single exhaust outlet coming out of the block.

 

[Bwalker]

Re: Premium Fuel ?

What kind of temps where you seeing at those locations?

 

[Bwalker]

Re: Premium Fuel ?

I think I misread Dhadley post. What he was saying was modern premium burns hotter than the olded leaded gasoline. If thats so I agree. EPA regs have changed the charachteristics of fuels greatly in the last 20 years..<br /> i might also add this change in temp from old to new my be a result of carb tuning and not the fuel itself. If the distallation curve of the fuel is change engine tunign parameters also change.

 

[Dhadley]

Re: Premium Fuel ?

The numbers vary with what version we are working with but one test we did that I remember the numbers exactly was with a V4 looper. It was on a Calif type ski boat (Starcraft Ca-Am by Warlock) and was set up at 6500-6600 rpm for skiing. As you see the motor was never under stress. There were 2 tanks on board, 87 in one and 93 in the other. <br /><br />On a long set cruise the exhaust temp was 925 with the 87. We never touched the throttle or trim -- just switched the tank valves. With the 93 it would climb to 960-975. Switch the valve back to 87 and it went back to 920-925. You could actually time how long it took to the gas to hit the carbs. It was pretty amazing really.<br /><br />We did the same thing on the dyno with everything from an outboard to 502 GM's.

 

[gator68]

Re: Premium Fuel ?

Dhadley !!! 4 stars and A+