Supreme unleaded fuel


15 replies to this topic
  • 2004greenkx250f

Posted July 04, 2010 - 02:16 PM

#1

After seeing the performance on my friend's CRF after he used Supreme in his bike I'm going to start using it in my bike. My question is will Supreme be okay to use in my riding lawn mower? (which has always used Regular unleaded) I use the same gas for my dirt bike and lawn mower and it would be cheaper not to have to buy Regular and Supreme in different gas cans.

  • highmarker

Posted July 04, 2010 - 02:24 PM

#2

crf and your kx250f should've been using prem all along (owners manual?) won't hurt the mower just your wallet

what altitude do you ride at?

  • DerHossMeister

Posted July 04, 2010 - 06:20 PM

#3

I've always used Premium, treated with Marine Sta-Bil, in all my equipment.

No worries!

  • Chokey

Posted July 04, 2010 - 07:05 PM

#4

Here we go, another "higher octane makes more power" thread...:)

FYI, any MX bike requires at least 95 RON octane, which will typically be around 90-91 (RON+MON)/2 coming out of the pump.

  • yz144builderlol

Posted July 04, 2010 - 08:45 PM

#5

I believe stock bikes run fine on normal pump gas and the only reason for high octane gas is for higher compression pistons. like chokey said, higher octane does not make more power. you need a higher compression for that and it gets complicated there..

octane is how good the fuel resists preignition. technically it might add insignificant amounts of power, something like 1/5th of a percentage point or something? (.2%)

  • Chokey

Posted July 05, 2010 - 05:54 AM

#6

I believe stock bikes run fine on normal pump gas and the only reason for high octane gas is for higher compression pistons. like chokey said, higher octane does not make more power. you need a higher compression for that and it gets complicated there..

Most stock bikes still need premium pump fuel.

octane is how good the fuel resists preignition.

Octane determines a fuel's resistance to detonation, not pre-ignition. Two separate issues.

Detonation is, in the simplest terms, an explosion, just as it's name implies.

To understand detonation, you first have to understand normal combustion. When the spark plug fires, it creates what is called a "flame kernal" between the electrodes. This tiny flame rapidly spreads in all directions, a smooth wave of burning fuel that continues until it reaches the edges of the combustion chamber, burning all of the fuel/air mix very rapidly, but very smoothly. The burning fuel mixture creates a tremendous pressure rise inside the combustion chamber. It is this pressure rise that propels the piston down the cylinder, turning the crank shaft. The pressures created inside a modern motocross engine can be as high as 30 atmospheres (440 psi).

Detonation, on the other hand, is not normal, smooth combustion. As the fuel/air mixture is being compressed in the engine, the heat and pressure begins to degrade the fuel at the molecular level, creating very unstable molecules called free-radicals. If the concentration of these free radicals becomes great enough, the fuel can spontaneously ignite over a large area all at once, creating a very sudden and violent explosion. This can happen before the plug fires, or it can happen in front of the flame-wave-front, in the remaining unburned fuel/air mix at or near the periphery of the combustion chamber. This explosion creates a much greater pressure rise in the combustion chamber (and much higher temperatures) than normal combustion, and it creates very fast-moving, very powerful shock waves. These shock waves strike the surface of the piston crown and the head with tremendous force, almost like hitting the metal with a hammer. It's this impact of the shock waves that makes the familiar "ping" sound that we associate with detonation.

The shock waves are also what leads to the damaged pistons that we see in a bike with a detonation problem. During normal combustion, the surface of the piston is protected from the raw heat of the burning fuel by a thin layer of unburned fuel, a few molecules thick, that clings to the surface. The shock waves produced by detonation blow this protective layer away, exposing the aluminum piston surface to the heat of combustion. The detonation also causes excessive temps, due to the extreme pressure rise that is well beyond what is created during normal, smooth combustion. The combination of high temps softening the piston, the protective layer being blow away from the piston surface, and the force of the shock waves, literally blows little bits and pieces of aluminum from the piston surface.

Pre-ignition is also exactly what it's name implies. The fuel/air mixture is ignited before the ignition fires, by a seperate heat source, such as a glowing spark plug electrode, hot carbon deposits, red-hot exhaust valves, etc. Pre-ignition does not cause any audible symptoms, but it can (and almost always does) lead to detonation.

Pre-ignition can also lead to the dreaded "runaway engine" syndrome. You've all heard the stories of guys bikes revving uncontrollably on the stand, and the kill switch having no effect. That engine is likely experiencing pre-ignition. Since the fuel is being ignited by a source other than the plug, hitting the kill switch can't stop the engine from running.

technically it might add insignificant amounts of power, something like 1/5th of a percentage point or something?

IF your bike is experiencing detonation, a higher octane fuel might result in slightly more power due to the elimination of the detonation. Otherwise, octane has no influence on power production. The power levels that can be produced from a particular fuel are determined by the burn rate of the fuel and the btu content, nothing else. And before someone decides to jump in and say it, NO, higher octane fuel DOES NOT burn slower. Octane ratings and flame propagation rates are not inter-dependent.

  • Chokey

Posted July 05, 2010 - 06:01 AM

#7

After seeing the performance on my friend's CRF after he used Supreme in his bike I'm going to start using it in my bike. My question is will Supreme be okay to use in my riding lawn mower? (which has always used Regular unleaded) I use the same gas for my dirt bike and lawn mower and it would be cheaper not to have to buy Regular and Supreme in different gas cans.

To answer your question, no, premium fuel will not harm your lawnmower, but running a more expensive fuel than required certainly won't be cheaper than running regular instead of premium in the lawnmower, because premium costs more. It may be more convenient for you, but it won't be cheaper.

FYI, I also run my leftover bike fuel in all of my lawn equipment, and have done so for many years. Hell, I don't think my lawnmower has ever had non-pre-mix in it. :)

  • fivepointnine

Posted July 05, 2010 - 09:45 AM

#8

wont those crazy VP fuels add power (you know the $30/gallon stuff lol)

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  • ncdirtrider249

Posted July 05, 2010 - 09:57 AM

#9

Premium should always be used in modern four stroke dirt bikes. It is reccommended in the owners and service manual, along with your local dealer/OEM. The bike can run off regular, but it is not practical. Regular grade fuels can add more carbon deposites inside the motor, along with less lubricating detergents which will cause premature wear on engine internals. I ALWAYS use premuim.

  • yz144builderlol

Posted July 05, 2010 - 11:58 AM

#10

wont those crazy VP fuels add power (you know the $30/gallon stuff lol)


I dont think you can use that stuff in a stock engine. the piston needs to be aftermarket from stock compression, then it makes a huge difference.

but if you mix it 50/50 or less with premium fuel maybe you can run it in a stock bike with minor improvements? im not sure.

  • OLHILLBILLY

Posted July 05, 2010 - 12:31 PM

#11

I've ran my 6hp B&S push mower on leftover 40:1 premix for 3 years now, with absolutely no problems. Your rider should handle straight 91 octane without a problem either.:)

  • Chokey

Posted July 05, 2010 - 12:53 PM

#12

wont those crazy VP fuels add power (you know the $30/gallon stuff lol)

Oxygenated fuels can add power in a stock bike with nothing more than jetting changes. Since the fuels contain substantial amounts of oxygen, they change the air/fuel ratio. Running richer jetting gives the engine more fuel to burn without being too rich, adding power. U4.2 is one of these.

There are race fuel formulations that will truly add significant horsepower because the formulations have higher btu content, but in most cases these fuels will require substantially higher compression to be able to use effectively. MRX01 is the best of these and was the Factory fuel of choice before the AMA unleaded rule. Now I believe most of the teams run MR-PRO4.1.

I dont think you can use that stuff in a stock engine. the piston needs to be aftermarket from stock compression, then it makes a huge difference.

There's a lot more to race fuel formulation than just higher octane. Consistent formulation is a huge advantage that will help keep your jetting more consistent than the ever-changing crap that comes out of gas pumps. In addition, a properly selcted race fuel for your application will have much more suitable vapor curves, allowing more complete combustion. The combination of these two issues means that, even in a stock bike, a correct race fuel for your application will reward you with more consistent, crisper, snappier response. The downside is cost. Only you can decide if the increased cost is worth the advantage. But anybody that tells you there's no advantage to running race fuel in a stock bike either has never tried it, doesn't know how to jet, chose the wrong fuel for their application, or is just parroting something they heard or read.

I used to use VP C12, and the throttle response was much better than with pump fuel no matter how good you are at jetting. I hardly ever get to ride any more, and I don't have a good local source, so I don't any more, but there's no denying the bike ran better.

but if you mix it 50/50 or less with premium fuel maybe you can run it in a stock bike with minor improvements? im not sure.

Mixing race fuel with pump fuel isn't improving the pump fuel, it's degrading the race fuel. And with the constantly changing pump fuel formulations, there is no telling what you'll end up with. all bets are off with jetting consistency if you go this route. Granted, it's better than blowing up an engine from detonation.

  • MELK-MAN

Posted July 05, 2010 - 12:59 PM

#13

I dont think you can use that stuff in a stock engine. the piston needs to be aftermarket from stock compression, then it makes a huge difference.

but if you mix it 50/50 or less with premium fuel maybe you can run it in a stock bike with minor improvements? im not sure.


(just noticed Chokey was posting at the same time i was..good comment about consistancy of the fuel)
Can't use in stock motors? Not totally wrong or totally right, you do need to pick the right application of fuel for your needs.
Here is info on VP fuels.. http://www.vpracingf...page469683.html
Some VP fuels will work just fine in stock motors. Remember, "Stock" in performance dirt bikes is not like 9:1 or some low number.. it is up there over 12:1.. that is equal to performance passenger cars that would also require super unleaded (not the cheaper stuff).
Take the MR9 (118$ for 5gal) i run in my roadracing r6 is 87octane, but is oxygenated (need to use it or keep it in a lined sealed container). LOWER octane makes power IF you can resist detonation (sometimes tough to do). This bike has the timing retarded (-4deg) up above 14,000rpm to resist detonation.

The question is on a crf450.. do you need more power.. I would venture to say that 98% of the riders (myself included) can't use what it has now effectively.

U4.2 or u4.4 are probably the best "bang for the buck" ($12/gal?? ) but take note of the jetting requirements. You will need to richen the bike up. Some of us mix 50/50 with pump gas to keep some performance gain but save some $$.

  • Chokey

Posted July 05, 2010 - 01:20 PM

#14

Take the MR9 (118$ for 5gal) i run in my roadracing r6 is 87octane

That statement is a bit misleading to those that don't know much about fuels. MR9 is 87 MON octane, which is not how pump fuels are rated in the US or Europe. If rated by the US pump standard of (RON+MON)/2, it would be approximately comparable to a 91-93 octane pump fuel. Typically the MON rating of US pump fuel is 8-10 points lower than the RON rating.

One thing to keep in mind if using an oxygenated fuel is what chemical is used to increase oxygen content. If ethanol is used (like in the garbage that comes out of pumps), then the btu content drops significantly, negating the benefits of the extra oxygen. Fuel consumption goes up while power stays the same or even goes down.

  • Smokey1226

Posted July 05, 2010 - 01:47 PM

#15

We'll im happy to see a few of you truely know quite a bit about fuels (as that is what i do for a living) however one thing i want to point out is ^^^^ in the above post Ethanol....is a natural oxygenator. Not quite to the level of VP 113/Q16/U4.4/MR12/MX01/Pro4.1 but you get the idea. So, with that in mind for the guys that do run 93 premium with ethanol and then switch to a fuel like C12...you might be running on the rich side. Always check plugs.

  • Chokey

Posted July 05, 2010 - 02:14 PM

#16

We'll im happy to see a few of you truely know quite a bit about fuels (as that is what i do for a living) however one thing i want to point out is ^^^^ in the above post Ethanol....is a natural oxygenator. Not quite to the level of VP 113/Q16/U4.4/MR12/MX01/Pro4.1 but you get the idea. So, with that in mind for the guys that do run 93 premium with ethanol and then switch to a fuel like C12...you might be running on the rich side. Always check plugs.

If switching to something like C-12 from pump fuel, you'll definitely be rich, because the 90% evaporation point is 228°F and the end point is 233°F. Pump gas typically has a 90% point as high as 305F and an end point as high as 370F. With the short intake tracts of our machines, all of the fuel doesn't evaporate, lowering combustion temps and making throttle response mushy, and requiring richer jetting just to avoid being lean. With the low vapor points of C-12, all of the fuel will evaporate before it enters the combustion chamber, so there is actually more fuel available for combustion. With stock jetting (or correct pump fuel jetting) there will usually be TOO much fuel present.





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