CHARACTERIZING FUEL BY GAS CHROMATOGRAPHY: MAKING SURE THAT INDYCAR RACE TEAMS ARE PLAYING BY THE RULES
You pull into your local gas station to fi ll up. Assuming you remember which side your gas tank fi ller cap is on, and what is the optimum grade for your car, you start pumping gas into your tank. But have you ever wondered why most of the gasoline now sold in the United States contains ethanol. Depending on where you live, you will fi nd three general categories of ethanol-gasoline blends …. E10, E15, and E85, which is gasoline containing up to 10%, 15% and 85% fuel-grade ethanol respectively. The majority of motor gasoline sold in the US does not exceed 10% by volume, but up to 15% ethanol content is sold in the Midwest….and in particular the corn-belt, where most of US ethanol production capacity is located.
Ethanol Blended Gasoline
Ethanol is blended into U.S. motor gasoline to meet the requirements of the 1990 Clean Air Act and the Renewable Fuel Standard described in the Energy Independence and Security Act of 2007, which is administered through the U.S. EPA’s Renewable Fuel Standard Program. All gasoline engine vehicles manufactured today can use E10. However, only fl ex- fuel (FFV) and light-duty vehicles manufactured after 2001 are approved by the EPA to use E15. A fl exible-fuel vehicle (FFV), sometimes known as dual-fuel vehicle is an alternative fuel vehicle with an engine designed to run on more than one fuel. This is usually gasoline blended with either ethanol or methanol, which are stored in the same common tank. It’s also important to emphasize that FFVs can use E85 fuel. Except for a few engine and fuel system modifi cations, they are identical to gasoline-only models. FFVs experience no loss in performance when operating on E85, and some generate more horsepower than when operating on gasoline alone. However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 15%–25% fewer miles per gallon when running on E85 fuel.
INDYCAR Racing
If you are an avid follower of motor racing, such as Formula 1, NASCAR or INDYCAR, you probably know that good fuel consumption is just one component in designing a race car. Fuel consumption is just as important as horsepower, torque and performance. Take for example the fuel that’s used by cars in the Indianapolis 500, the premier race of the Verizon IndyCar Series. Verizon IndyCar Series race cars are shown in Figure 1.
The IndyCar organization has tried a number of different fuels over the years, including 100 percent fuel-grade ethanol and methanol with various mixtures of gasoline. From 2007-2011, the mixture was 98% ethanol and about 2% racing gasoline which had an octane rating of 113. Octane rating is the measure of a fuel’s ability to resist “knocking” during combustion, caused by the air/fuel mixture detonating
prematurely in the engine. In the U.S., unleaded gasoline typically has octane ratings of 87 (regular), 88–90 (midgrade), and 91–94 (premium). Today the IndyCar Series is using a variation of E85, which contains 85% ethanol and 15% high- octane racing fuel, which delivers an octane rating of 105. So it can be seen that the fuel for an IndyCar is signifi cantly higher octane rating that gasoline we buy from the pump. This is the reason they can lap at an average speed of 210 mph, with top speeds of over 230 mph. But the downside is that it has a huge impact on the car’s fuel consumption….it’s been estimated that 1.3 gallons of fuel are used every lap of an Indycar race…in other words, less than 2 miles per gallon.
Clearly the Octane rating has a signifi cant impact on the performance of a car, because all the IndyCars are of a similar design. They are all single-seat, open-cockpit car that feature a 2.2-liter, twin turbocharged, direct-injected V-6 engine supplied by Chevrolet or Honda, which are optimized to run at 12,000 RPM with an estimated 500-700 horsepower depending on the turbocharger boost setting. However, there are other ways of getting an edge at certain times during an IndyCar race, such as a turbocharger boost pressure called “push-to-pass”, which was initiated about half-way through the 2015 season. This is a switch inside the cockpit, which will give the drivers an extra boost when they are trying to pass a car in front of them. However, they are only allowed to use this feature a maximum of 10-times per race, as explained by Marvin Riley, the Director of Engine Development of the Verizon IndyCar series:
“It is estimated that this will increase the internal engine pressure from 160 kilopascals (kPa) to 165 kPa, translating to a gain of approximately 20 horsepower in the Chevrolet and Honda engines. Normal boost pressure on road and street courses – before the overtake assist is engaged – remains at 150 kPa in 2016. A total of approximately 60 added horsepower will now be available for push-to-pass activations during the 16 road- and street-course races in the 2016-17 racing season (March-September), nearly doubling the on- track effect for passing over 2015.”
Fuel Testing Protocol
The rules and regulations in the design of an Indycar are very strict, so it’s extremely diffi cult for teams to gain a signifi cant advantage, when the cars are a similar weight, engine type, engine size, gearbox, chassis, cockpit, wheelbase, tire, suspension, gas tank size and fuel (1). So for that reason, the race result is very much dictated by the skill and expertise of the drivers. In addition, one of the major areas of enforcement is in the fuel used. It is supplied by the same oil company (Sunoco: E85 fuel) and pumped from the same underground tank, containing exactly the same mixture of ethanol and gasoline. Fuel quality is such an important component of the rules that for the past 40 years, the Indianapolis 500 and more recently, the Verizon IndyCar Series has used one company to carry out all the fuel testing to ensure that no teams are getting an edge by using illegal additives to give their cars an octane boost.
History of Fuel Testing
In 1995, Tim Ruppel, a Senior GC Applications Specialist at PerkinElmer was involved in the initial development of the gas chromatographic testing method including selecting the appropriate column material, stationary phase, fi lm thickness, column length, and diameter to provide an effi cient separation of potential volatile compounds in the race fuel. The current method which combined two methods, each with analysis times of 20 minutes has been optimized into a single method that takes less than fi ve minutes to carry out a complete separation, as exemplifi ed by the chromatogram of E85 fuel in Figure 2.
Let’s take a closer look at the logistics of testing the fuel in an IndyCar race.
All cars receive Sunoco fuel from a central source. During pre-race qualifi cations and the race itself, fuel is delivered to each team’s pit fuel tank. Each tank is sealed to prevent tampering. Fuel is delivered by gravity feed, and each tank’s
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Figure 1 (Above): INDYCAR race cars (courtesy of INDYCAR)
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