RACER’S GUIDE TO THE HIERARCHY OF MOTOCROSS RACING FUELS

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March 17, 2014
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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—determine which VP gas to use and when.

 

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 60º 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 60º 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 60° 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 60° 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 60° 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.MRX02 FUEL VALUES

Category:


Leaded/oxygenated
Type:
Leaded with MTBE

Color:
Light blue

Specific gravity:
0.734 at 60° 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 60° 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 60° F

RVP: 10.87

Oxygenated: Yes

MON: 87

RON: 104

R+M/2: 95

Engine: Four-stroke

 

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