Looking to run race fuel, a mixed fuel, or fuel additives? This is an in-depth topic with many specifics, but we are going to try and keep things simple and to the point. Octane is the name of the game. In our UTV tunes you’ll often find we offer race fuel, race fuel additive, or E-85 tunes. More power can be made with these fuels and it makes more sense with an off-road vehicle that is ridden only occasionally. The added cost of some of these fuels can make the vehicle that much more powerful and fun to drive! Turbocharged vehicles will benefit the most from added octane.
Additives such as VP Octanium, Boostane, Torco Accelerator, Race-Gas Concentrate: We really like these products as they are easy to carry with you on the trail or bring to the dunes. These fuel additives are a race fuel concentrate in a 32oz can. All of our Level 4 turbocharged tunes for RZR Turbo & X3 models are developed by testing with these products, or a 50/50 110 race fuel mix. Either way will work. The fuel additives are mostly unleaded versions using MMT to increase octane. This will turn engine/exhaust parts orange. Keep in mind some are better than others at preventing phase separation. If exposed to light or if it sits too long, the MMT will separate from the fuel and cause small flakes in your fuel, or potentially gum up. This is somewhat rare, but VP Octanium and Race Gas both sell leaded or unleaded versions. Leaded versions will not phase separate. Keep in mind using a leaded additive or fuel may caused reduced life of your O2 sensor. Read below for more on leaded fuel. **Note: We have confirmed with VP that Octanium/Madditive cannot be mixed to go above 100 octane. Race-Gas does offer an additive that will take pump fuel up to 112 octane (1 can of Race Gas Ultra with 4 gallons of 93 octane).
Octane boosters like Lucas and others available at the auto parts store: These boosters are to prevent a little amount of engine knock. They are fine to run with our pump gas tunes, but have no huge benefit other than to keep your motor from sensing detonation/knock and pulling timing. That is important as well, especially when fuel quality is potentially low, or you are riding hard like in the dunes. It’s not needed, but will keep power more consistent.
Leaded Race Fuels: If you run leaded fuel, you run the risk of your O2 sensor failing or reading incorrectly. With an additive or mixing with pump gas, you are less likely to have this issue. We always suggest keeping a spare O2 on hand (we have these available for purchase for most models). We have personally gone 50+ tanks of full leaded fuel without any issue, and on other vehicles had an O2 fail after a few tanks of leaded fuel. When an O2 sensor fails it normally throws a code but can also cause a lean or rich condition. You should not have a catalytic converter when running leaded fuel as it will make it inactive, and you’ll just have a restriction. Leaded fuels are great and a reliable fuel for octane that is very stable…. but just use a little bit of O2 sensor caution.
Unleaded Race Fuels: Motorsport 109 is a great unleaded race fuel to run with our Level 5 tune, or mixed 50/50 for Level 4. This has a great octane rating and would be plenty for most. Others sell unleaded race fuels like this as well. Make sure you read below on specific gravity if selecting another brand fuel of this type.
UTV96: This fuel basically acts like 98-100 octane in our testing. A few companies make fuels similar to this. You can run our Level 4 tunes with this fuel.
More octane is normally okay! We get his question… we would much rather have more octane than not enough. If you have extra race fuel and you run a lower level pump gas tune, you will be fine running extra octane. Honestly, if running hard it’s not a bad idea to bump your octane up a few points, and will make up for fuel quality inconsistencies. Adding some octane to your pump gas normally ensures you’ll have no engine knock. When these vehicles equipped with a knock sensor sense engine knock, timing is removed until knock levels come down to a safe point. Having extra octane will ensure you are at peak timing levels for maximum and consistent power. If you have too much octane, you won’t quite get the same flash in the cylinder, and power can decrease… but as long as you are not way overboard with octane (say 110 straight with a pump gas tune), you will most likely gain power rather than feel any sort of loss.
E-85 Corn Fuel! The amount of power we can run on this fuel is absolutely crazy and the pump fuel is normally cheap. It’s also a very cool burning fuel which helps keep engine temps down. However, E-85 does have some downfalls. Pump E-85 can be inconsistent, so you want to make sure you test your fuel with an ethanol test kit for at least 70% ethanol with our tunes, and no greater than 85%. E-85 from race fuel suppliers like VP fuels is consistent, but more expensive. E-85 fuel should not be mixed with other fuels if you can help it. We suggest having less than 1 gallon in the tank when switching, but ideally an empty tank is best. The same thing should be done when switching back to pump gas/race gas. E-85 also burns much more fuel. Depending on the model, we are adding 20-30% more fuel at wide open throttle. This is fine for most riding in areas not far from camp or home, but not ideal for most trail riders.
Flash points: More octane is harder to ignite which is why it works so well under more pressure without detonation. This also makes it harder to ignite at startup. Keep this in mind when selecting a tune for winter months if your area is very cold. More octane or E-85 will take a few extra cranks and can be hard to start when it’s very cold.
Specific gravity: Pay attention to this when you are selecting a race fuel. Normal pump gas 91-93 octane is .720 to .760 specific gravity. We suggest finding a race fuel around that same range for best running characteristics. Most common fuels are right around that SG.
O2 Sensor/Fuel Corrections: Vehicles with O2 sensors will normally adapt fueling for small differences in specific gravity. Currently Polaris has black O2 sensors which are narrow band and all Can-Am X3 turbocharged models are a narrow band sensor. These will adapt slightly for different fuels/intake/exhaust.. etc.. If they cannot adapt enough you will see a code come up which is extremely rare. With wideband models you need to make sure you keep a closer eye on specific gravity. Polaris also has wideband models with a blue O2 sensor found on some XPT, Turbo S, and all Pro XP models. These will adapt fueling up to 25%, so you will have less issues with different specific gravity.
AV gas is a somewhat popular fuel we are asked about.. the specific gravity can be very low on 100LL (.680 to .740), so the vehicle may run a little leaner than normal. The vehicle may not be able to trim enough fuel depending on the model. We suggest adding octane another way but 100LL normally works fine with our Level 4 tunes. We do offer a 100LL AV Level 4 tune for some models.