RACER’S GUIDE TO THE HIERARCHY OF MOTOCROSS RACING FUELS

On Mar 10, 2017 Last updated Mar 10, 2017

Knowing how to choose the right type of racing fuel for your bike can be confusing. You probably know that octane is not the make-it or break-it number when it comes to choosing race gas—and that a higher octane number might actually hurt performance if your engine doesn’t call for it—but what other factors should you consider. Four-strokes run best on unleaded fuel and two-strokes prefer lead, but are there exceptions to this rule? The MXA wrecking crew has a long track record with VP Racing fuels, so we sat down with VP execs to hash out the hierarchy of racing fuels. We wanted to help other racers—who are probably as confused as we are. We want to help you determine which VP gas to use and when. It should be noted that VP comes out with new fuels all the time and these are not the only fuels they make. But, these are the fuels that most motocross racers use.

VP-110:
LEADED/NON-OXYGENATED
Usage: A high-octane, leaded, non-oxygenated fuel that bridges the gap between pump gas and C12 for use in stock or modded two-strokes.
Preferred engine type: Two-stroke.
Antiknock octane: 110.
Features: VP-110 has the highest Motor Octane (MON) rating of any 110 fuel on the market at 107. It is formulated for use in all naturally aspirated engines with compression ratios of up to 13:1.
Bottom line: VP-110 is a good, all-around fuel for hopped-up two-stroke engines. MXA mixes VP-110 with pump gas for use in slightly modified two-stroke engines in mixtures from 25/75 to 50/50.

VP-110 FUEL VALUES
Category: Leaded/non-oxygenated
Type: Leaded
Color: Green
Specific gravity: 0.720-0.735 at 60§ F
RVP: 6.6
Oxygenated: No
MON: 107
RON: 113
R+M/2: 110
Engine: Two-stroke

C12:
LEADED/NON-OXYGENATED
Usage: The preferred race fuel for all highly modified two-stroke racing engines.
Preferred engine type: Two-stroke.
Antiknock octane: 113.
Features: This good old standby has been the best all-around two-stroke racing fuel made for hopped-up engines for the last couple decades. It is recommended for compression ratios as high as 15:1 and is the go-to gas for any ported, milled and modded engine. It has been the hot topic fuel for years.
Bottom line: VP’s C12 is the winningest, high-octane, two-stroke racing fuel in motorsports history; however, it is too cool for stock powerplants.

C12 FUEL VALUES
Category: Leaded/non-oxygenated
Type: Leaded
Color: Green
Specific gravity: 0.717 at 60§ F
RVP: 7.3
Oxygenated: No
MON: 108
RON: 117
R+M/2: 113
Engine: Two-stroke

T4:
UNLEADED/OXYGENATED
Usage: T4 is the four-stroke version
of VPR. It is an all-around race fuel for stock four-stroke engines.
Preferred engine type: Four-stroke.
Antiknock octane: 100.
Features: T4 is designed for stock four-stroke engines. Unleaded and ethanol-free, T4 is a direct, pour-in replacement for premium pump gas. T4’s 100-octane rating (R+M/2) provides greater protection against detonation. Compared with more expensive performance enhancements that increase power along only a small slice of the power curve, T4 offers 3 percent more power and better throttle response across the entire rpm range.
Bottom line: T4 is the four-stroke version of VPR. With a 100 R+M/2-octane rating, it has 5 octane less than VPR. The lower octane makes it better for most stock four-stroke engines.

T4 FUEL VALUES
Category: Unleaded/oxygenated
Type: Unleaded with MTBE
Color: Yellow
Specific gravity: 0.745 at 60ø F
RVP: 8.54
Oxygenated: Yes
MON: 93
RON: 108
R+M/2: 100
Engine: Four-stroke

VPR:
LEADED/OXYGENATED
Usage: A less expensive, leaded and oxygenated two-stroke fuel that bridges the gap between pump gas and race gas.
Preferred engine type: Two-stroke.
Antiknock octane: 105.
Features: Offering 2 percent more power, better throttle response, increased consistency and long term savings over pump gas, VPR is clearly what your stock (or slightly modified) bike needs. Ethanol-related problems will not be an issue with VPR, and you can expect better vaporization and a cleaner, more-efficient burn than with pump gas.
Bottom line: VPR is the leaded version of T4 fuel, and because of the lead, it is better for two-strokes. Four-stroke owners should use unleaded T4.

VPR FUEL VALUES
Category: Leaded/oxygenated
Type: Leaded with MTBE
Color: Pale green
Specific gravity: 0.732 at 60ø F
RVP: 8.5
Oxygenated: Yes
MON: 101
RON: 109
R+M/2: 105
Engine: Two-stroke

U4.4:
LEADED/ OXYGENATED
Usage: U4.4 is for riders looking for the kick of oxygen who are not bound by fuel rules.
Preferred engine type: Two-stroke or four-stroke.
Antiknock octane:108.
Features: Designed as a direct, pour-in replacement for pump gas, it will require modest jetting changes (typically two mains bigger). With its higher octane rating, U4.4 is designed for use in stock and
modified two-strokes and four-strokes. If you’re not bound by fuel rules, this leaded fuel is the best choice if you’re looking for big horsepower gains.
Bottom line: This is the original oxygenated motocross fuel. Although VPR and T4 are more economical versions of U4.4 (they cost about $3 a gallon less), they have less oxygen and octane than U4.4.

U4.4 FUEL VALUES
Category: Leaded/oxygenated
Type: Leaded with MTBE
Color: Light Green
Specific gravity: 0.763 at 60ø F
RVP: 6.76
Oxygenated: Yes
MON: 103
RON: 114
R+M/2: 108
Engine: Two- or four-stroke

MRX02:
LEADED/OXYGENATED
Usage: A high-end two-stroke fuel that offers the benefits of added oxygen and a 100-octane Motor Rating. It
contains enough octane for highly
modified two-strokes but is
oxygenated for more power.
Preferred engine type: Two-stroke.
Antiknock octane: 104.
Features: Arguably the best-performing two-stroke motocross fuel for modified engines. Surpassing most other fuels, MRX02 is effective in delivering up to 7 percent more power than pump gas or any basic non-oxygenated race fuel. This high-end fuel blend is legal for AMA Pro/Am and local racing.
Bottom line: MRX02 is a top-level two-stroke fuel. Although it has less oxygen than U4.4, it actually makes more power.

MRX0212 FUEL VALUES
Category: Leaded/oxygenated
Type: Leaded with MTBE
Color: Light blue
Specific gravity: 0.734 at 60ø F
RVP: 9.0
Oxygenated: Yes
MON: 100
RON: 108
R+M/2: 104
Engine: Two-stroke

MR12:
LEADED/OXYGENATED
Usage: A low-octane fuel that works best on four-stroke engines.
Preferred engine type: Four-stroke.
Antiknock octane: 93.
Features: VP’s best fuel for four-stroke applications that can tolerate lower octane values. MR12 makes up to 5 percent more horsepower but is not legal for AMA Pro racing because of its oxygen content. It can be used in AMA Pro/Am, NMA, WORCS, SCORE and local racing.
Bottom line: MR12 is the four-stroke version of MRX02. It has more octane and more oxygen content than pump gas.

MR12 FUEL VALUES
Category: Leaded/oxygenated
Type: Leaded with MTBE
Color: Light green
Specific gravity: 0.733 at 60ø F
RVP: 11.6
Oxygenated: Yes
MON: 87
RON: 99.2
R+M/2: 93
Engine: Four-stroke

MR-PRO6:
UNLEADED/OXYGENATED
Usage: An unleaded race fuel that meets the standards of AMA Pro racing for Supercross and AMA Nationals.
Preferred engine type: Four-stroke.
Antiknock octane: 95.
Features: MR-Pro6 is an unleaded fuel engineered to generate maximum horsepower in four-stroke applications while still conforming to the AMA rules for lead and oxygen content. MR-Pro6 delivers more power, thanks to its carefully formulated oxygen and octane content. It requires minimal jetting/mapping changes and will not require radical changes in ignition timing. This unleaded fuel makes the equivalent power of leaded MR12.
Bottom line: This is a top-level, legal AMA Pro racing fuel. AMA Pro racing has limits on oxygen content, specific gravity and additives. AMA Pro racing rules are much stricter than AMA Amateur or local fuel rules.

MR-PRO6 FUEL VALUES
Category: Unleaded/oxygenated
Type: Leaded with MTBE
Color: Clear
Specific gravity: 0.724 at 60ø F
RVP: 10.87
Oxygenated: Yes
MON: 87
RON: 104
R+M/2: 95
Engine: Four-stroke