vp u4 fuel

[johnny22]

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

[Pumashine]

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 60º F

[jamieg45]

U4 is a oxygenated fuel my buddy runs it in his daughters race bike.

[Pumashine]

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.

[johnny22]

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?

[jamieg45]

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.

[89Longrod]

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.

[johnny22]

Do you run u4 with the same compression you would with your race gas jamie?

[Crandles]

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.

[Rupp250]

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.

[Pumashine]

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?

[johnny22]

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

[Jerry Hall]

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.

[trx250-86]

Is it even really worth running race gas? is it really a noticeable difference?

[Pumashine]

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.