TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: johnny22 on November 01, 2013, 03:36:50 PM
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Anyone here ever run it? Is it worth running it over sunoco 112? Do you have to do anything to your carb to run it? Thanks for for any help
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From the description it is saying 103 octane verses 112 you get with the sunoco 112...Or am I missing something?
VP Racing U4.4 Racing Fuel - Details
This leaded fuel is the best choice for virtually any power sports application
Latest generation of VP Racing U4-based fuels
Makes up to 6% more power than pump gas across a wider range of applications than its predecessors
It yields no sticky residue and is more resistant to heat
Designed as a direct, pour in replacement for pump gas, it will require modest jetting changes, i.e. +2 main jets or +2 pilot jets at most
With a higher octane rating, U4.4 is designed for use in stock and modified 2-stroke and 4-stroke applications
Passes fuel rules for AMA Pro/Am, CCS, WERA, AFM, NMA, WORCS, SCORE and Best in the Desert as well as club level racing and more
5 gallons
Typical Values:
Color: Green
Motor Octane: 103
Specific Gravity: .763 at 60ยบ F
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U4 is a oxygenated fuel my buddy runs it in his daughters race bike.
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U4 is a oxygenated fuel my buddy runs it in his daughters race bike.
All my motors are set for 110. So I guess it matters what compression ratio your motor is set at.
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Yeah so i guess i would just have to make sure my compression isnt too high then huh? You think theres any gain over race gas?
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I can say what I have noticed with mine is they run better and cooler and the inside is much cleaner of a burn too. My motors are very high compression and ned race gas.
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From what I remember Niel recommended never using oxygenated fuel...But maybe he will chime in here. U4.4 is what the pro circuit 250F's run on and if i recall pretty expensive vs normal fuel.
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Do you run u4 with the same compression you would with your race gas jamie?
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U4.4 is an oxygenated fuel. The octain ratings would be figured different from traditional 110 race fuel. U4 is a nice upgrade in power from 110 at a pretty penny nun the less.
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U4.4 is an oxygenated fuel. The octain ratings would be figured different from traditional 110 race fuel. U4 is a nice upgrade in power from 110 at a pretty penny nun the less.
Not doubting you, but do you have proof that you made more power with the U4.4.
Just because you (not you actually) run a higher octane or exotic fuel does not mean you will make more power. On a LT80 I seen more power made with pump gas then 100.
I'm just saying you really won't know what it will do Johnny till you can run on a dyno and try it out yourself.
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U4.4 is an oxygenated fuel. The octain ratings would be figured different from traditional 110 race fuel. U4 is a nice upgrade in power from 110 at a pretty penny nun the less.
The info shows octane at 103. Are you saying 103 octane is an upgrade from 112? Or is the octane rating somehow derived differently?
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i wouldn't have a problem trying it but the only thing is i wouldn't know what to do with jetting ya know? it does sound weird that it would make more with less octane i guess. I would be worried about the octane not being high enough for the amount of compression
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i wouldn't have a problem trying it but the only thing is i wouldn't know what to do with jetting ya know? it does sound weird that it would make more with less octane i guess. I would be worried about the octane not being high enough for the amount of compression
The octane rating is a rating of a fuel's resistance to detonation not a rating of the fuel's power potential. If an engine only needs 90 octane fuel, putting 100 octane fuel in it will not hurt the engine nor will it increase the power unless the fuel is an oxygen bearing fuel.
Pump gasoline is a chemical cocktail that can be composed of many different chemicals. Different brands of race gas are also composed of different chemicals even though they may have the same octane rating. The chemical composition also determines the specific gravity, the heating value, octane rating and how the fuel reacts to heat and pressure during the combustion process
The heating value is usually higher on fuels that have a lower specific gravity and will need leaner jetting to make maximum power. Heavier fuel will usually need larger jets as well as oxygenated fuels when optimized for maximum power.
If a low octane fuel makes more power than a higher octane fuel and there is not any detonation issues. the jetting and ignition timing used with the race fuel was probably not optimized for the race gas. I recommend that you always use a fuel whose octane is at least 2 to 3 points higher that what the engine design requires.
Running a slightly higher octane fuel than what the engine needs, will help keep the engine from going into detonation if the engine is a little lean, a little hotter than normal or the fuel is not fresh. Most of the time you will not hole or seize a piston if you can keep detonation from occurring.
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Is it even really worth running race gas? is it really a noticeable difference?
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Is it even really worth running race gas? is it really a noticeable difference?
As Jerry says
If an engine only needs 90 octane fuel, putting 100 octane fuel in it will not hurt the engine nor will it increase the power
If you do not need race gas then yes you are wasting your money. If an engine needs 110 race fuel then yes there is a noticeable difference. You will ruin the piston is less than a day of use.
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As Jerry says
If you do not need race gas then yes you are wasting your money. If an engine needs 110 race fuel then yes there is a noticeable difference. You will ruin the piston is less than a day of use.
But what I'm asking is it worth it for the price?
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Do you run u4 with the same compression you would with your race gas jamie?
I my self do not run the u4.4 vp I run vp c12, the uv is like adding nitris to your gas. It runs great like I said my buddy runs it in every dirt bike his daughter races. He started out using it in her kx 80 and then her big bore bike and now even in her new honda 150 4stroke as well. I will ask him this weekend of the ups and downs and if it's a big gain for you Johnny22.
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Cool thanks jamie. Thank you all for the replies
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I prefer to run a race gas since most gas stations carry an ethanol blend.
This is agruably, the best reason why you should use race fuel!
But what I'm asking is it worth it for the price?
YES! Worth every bit of the money. :encouragement:
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But what I'm asking is it worth it for the price?
If your engine needs higher octane fuel than what you can buy at the pump to protect it from detonation, you have two options. Replace the piston daily or spend the money for higher octane fuel.
There are many options when it comes to spending money for higher octane fuel. The options revolve around your engine build (what octane fuel your engine requires) and what your budget will allow to spend for fuel.
If your engine requires 110 octane fuel you need to spend the money and buy the race fuel of your choice.
If your engine requires less than 110 octane fuel you can mix race fuel with pump gas to arrive at a blend that has the octane your engine requires.
I read a lot of stories on the net about the fear of running fuel that has ethanol, MTBE and other additives that the refineries in your area add. Any of these additives can affect the jetting. If your engine would run on pump gas without detonation, adding 15% ethanol or MTBE to your pump gas will require the fuel flow through the carburetor to be increased 5%. A 5% increase in fuel flow would require one to increase the main jet 1 to 2 sizes, and richen the needle less than 1 clip position and less than on increment in the pilot jet size.
I read a lot of stories on the net about guys telling everyone to run race fuel because it is consistent and is needed to keep your jetting consistent. If you use the same brand and octane rating from the same fuel manufacturer, this statement is true, providing you are getting fuel from unopened cans or drums. We are constantly repairing engines where customers bought fuel from a shop from a drum that was already opened and was said to be fresh, and undiluted. The damage to the piston head and top of the cylinder indicates the fuel was not what it was advertised to be.
All gasoline whether it is pump gas or race gas has different heating values. The heating value primarily determines what size jet must be used to provide optimum power. I see as much as a 2 to 3 main jet sizes difference in the optimum main jet sizes needed from different brands of racing gas of the same octane rating.
In summary:
1. Use fuel that is at least 2 to 3 octane points higher than what your engine requires.
2 Optimize your jetting on the fuel that will ALWAYS be available.
3. Do not change from one brand to another or one octane level to another unless you are prepared to go through the re-jetting process.