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E-85 Fuel, What It’s All About? 

E85 is a fuel that has been around for awhile and has been standard in the U.S automotive manufacturers since 1998. E in E85 stands for Ethanol, most common ethanol production in the U.S is corn, and 85 stands for 85% Ethanol in the fuel. E85 has a higher-octane rating than normal pump gas 91-93 octane, but Ethanol is roughly 30% less efficient than gasoline due to a lower burn rate, which also intel’s more fuel consumption. E85 is a perfect match for higher boost and modern high compression engines. The alcohol content in E85 actual keeps engines cooler by cooling down the incoming air/fuel charge which is necessary in high heat forced applications. The cooler the air, the denser the air which relates to more power. 

Can I Use Pump E85? 

You can use pump E85, however NEVER use pump E85 in any off-road vehicle without testing it first. You can purchase a E85 fuel tester at any auto parts store for a few dollars. You can use a range of 80%-88% Ethanol, nothing under or above that rating. The U.S Department of Energy allows refineries to use 51% to 83% Ethanol in pump E85 fuels. Depending on geography and seasons in the U.S. each gas station will vary Ethanol ratings. For example, in Wisconsin during the winters it can reach -30-degrees Fahrenheit and on-road vehicles will not start on high Ethanol so the refineries will add more fuel making it E70. If you use incorrect pump E85 in your off-road vehicle you can damage the engine.  

Where Can I Get Off-Road E85? 

There are many performance fuel companies out there that refine the correct blend of E85 that off-road vehicles need. Performance fuel companies blend E85 with exactly 85% Ethanol and 15% top quality hydrocarbon race fuel. Off-road E85 will have an octane rating of 100+, depending on the manufacturer. For example, VP Racing Fuels has X85 with an octane rating of 101.6 (R+M)/2 and 108 RON. SUNOCO Race Fuels has E85-R with an octane rating of 99 (R+M)/2 and 104 RON. Because race E85 is highly oxygenated and requires increased fuel flow, consult with your motor builder or specialty ECU tuner before you switch over.    

Mixing Fuels and Calculating Octane 

When your engine builder or tuning company recommends a different octane rating than what is available around your area, sometimes you need to mix two different fuels to obtain the correct octane rating. Here is the correct way to mathematically calculate fuel ratings. 

(% Fuel A ÷ Desired Gal) X (Octane Fuel A) + (% Fuel B ÷ Desired Gal) X (Octane Fuel B) 

Example 1: How to Mix 100 Octane 

Fuel A = 110 

Fuel B = 91 

Desired Gallons = 5 

(2.5 ÷ 5 Gal) X (110 Octane) + (2.5 ÷ 5 Gal) X (91 Octane) = 

(.5) X (110 Octane) + (.5) X (91 Octane) = 

55 + 45.5 = 

110.5 Octane 

Example 2: How to Mix 93 Octane 

Fuel A = 100 

Fuel B = 91 

Desired Gallons = 5 

(1.0 ÷ 5 Gal) X (100 Octane) + (4.0 ÷ 5 Gal) X (91 Octane) = 

(.2) X (100 Octane) + (.8) X (91 Octane) = 

20 + 72.8 = 

92.8 Octane 

Difference Between Fuel Ratings 

North American Region (NAR) uses the Anti-Knock Index (AKI), (RON+MON)/2, or (R+M)/2 when describing octane. In the Rest of the World (ROW), RON is used when describing octane. RON is the Research Octane Number and MON is the Motor Octane Number. 

Anti-Knock Index (AKI) or (R+M)/2 

In most countries in Europe (also in Australia, Pakistan and New Zealand) the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2.  

Difference between RON, MON, and AKI 

Because of the 8 to 12 octane number difference between RON and MON, the AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel. This difference between RON and MON is known as the fuel's sensitivity and is not typically published for those countries that use the Anti-Knock Index labelling system.  

As represented by their AKI and minimal octane ratings, there are currently three grades of traditional gasoline available in the U.S.: 87 (regular), 88 to 90 (mid-grade) and 91 to 94 (premium). For example, a 95 RON plus an 87 MON averages to a 91 AKI, which is the octane rating you would see displayed on a U.S. retail fuel site dispenser. The 95 RON and the 87 MON ratings can be derived from the exact same fuel. The test to determine the MON is more challenging than the RON test, and that’s why the RON test yields a higher number. Adding to the confusion: Europe uses the RON to label the fuel’s octane rating at the dispenser. 

Primary springs live within the drive clutch, also known as the primary clutch. The primary spring controls engagement rpm and operating rpm throughout low-high end.

·         Longer, stiffer, more coils on the spring will equate to higher rpm engagement.

·         Smaller, less stiff, less coils on the spring equate to lower rpm engagement.

Look behind the driver's seat for a finned, silver metal box like the one shown in the pic below. If you XP Turbo/S has this device, it's an FPCM model.