Filthy myths run rampant when it comes to understanding race gas. Some say that the higher the octane the slower the burn rate. Others claim that too much octane reduces horsepower. Unfortunately, both of these blanket statements are terribly inaccurate, and we magazines are the scoundrels largely responsible for misinforming the public. So lock us in a cell and make us watch HGTV. Making amends for our past transgressions and putting an end to the controversial topics surrounding race gas requires an authoritative voice. For that, we went straight to the top and chatted with Tim Wusz of Rockett Brand Racing Fuel.
If you haven't heard of Rockett Brand, it's because the company has only been around-at least on paper-for a few years. However, its team of engineers has been the foremost authority on blending powerful racing fuels for nearly 50 years. After Conoco Phillips bought out 76 in 2003, its corporate bean counters viewed the racing endeavors of its new acquisition as a frivolous expense. Consequently, the new owners pulled the plug on the 76 Racing Fuel Group. Fortunately for racers, the scientists and engineers responsible for 76 Racing Fuel's unparalleled success went on to form Rockett Brand. Tim Wusz is one of those guys. He earned a mechanical engineering degree from Oregon State University and went to work for 76 in 1965. For over three decades, Tim formulated proven racing fuels for everything from NASCAR to the upper ranks of NHRA competition. Needless to say, he knows a lot more than you, so listen up.
Octane DefinedAlthough an octane number is generally associated with fuel quality, few people understand the true definition of octane. The short answer is that octane is a fuel's resistance to detonation, but there's more to it than that. When crude oil is refined, it is broken down into hydrocarbon chains of various lengths. Hexane has six carbon atoms chained together, heptane has seven, and octane has eight. "When the octane number scale was established in the late 1920s, normal heptane was the bottom of the resistance-to-detonation scale and was therefore assigned an octane number of zero," says Tim. On the other hand, the octane isomer isooctane had very good resistance to detonation and was assigned an octane number of 100. These two components are used to establish a reference fuel system, and the percentage of isooctane in the blend is the octane number. When an unknown sample is tested, it is compared to the known octane numbers of the isooctane/normal heptane blends. For octane numbers over 100, tetraethyl lead (TEL) is added to isooctane. "The top end of the octane scale is slightly over 120, so don't be fooled by someone that claims to have 125- or 130-octane gasoline."
Gas BrandsSome people fill up their cars wherever gas is the cheapest, while others drive all the way across town to find a certain brand. So is there really a difference between different brands of pump gas? "There are many regulations in place that control what gasoline companies can do as the government gets more involved," says Tim. "There is very little difference between the major gasoline brands today in any given geographical location. The main difference is the detergent additive packages they use, which can make one brand unique from another. However, it is very hard to identify these additive packages because the amount in the gasoline is very small."
Pump Gas CompatibilityMost enthusiasts would agree that true street cars burn pump gas, not race gas. Using common sense will ensure that a hot street motor won't detonate to smithereens. "Optimizing quench is critical, and aluminum heads reduce the possibility of hot spots compared with most iron heads," advises Tim. "Some simple things you can do to help the octane situation is making sure the cooling system is adequate enough to keep the coolant temperature around 180 degrees." Reducing inlet air temperature with a cowl-induction system or a scoop is also a good idea. "For every 25 degrees of reduction in inlet air temperature at the top of the air horn the engine octane requirement is reduced by one number." Water injection is also an option, particularly in dry climates such as the Southwest. Rockett Brand makes a street-legal 100-octane unleaded gasoline that can be blended with regular pump gas to boost octane.
PowerSome motors pick up power when running race gas and others don't, so it's hard for people to determine whether or not they need to step up to a higher-quality fuel. According to Tim, if you notice a change in power, it's probably due to incorrect tuning. "The gasoline is like any other component in the engine: It is part of a package designed to make horsepower," he explains. "The air/fuel ratio must be correct as well as the spark timing. Different gasolines have different burning characteristics that require optimizing the spark timing and air/fuel ratio. The tune-up step is critical. Sometimes, when using unleaded gasoline that contains an oxygen compound, more power can be developed because the oxygen in the gasoline acts like a small dose of nitrous, or like higher barometric pressure. Some street gasolines have up to 3.5 percent oxygen."
Fuel ChecksEach sanctioning body has its own procedure for testing gasoline, and inspectors can use several methods to crack down on cheating. At the inspectors' disposal is a list of the gasolines that are eligible for use at an event, and specs on those fuels such as color, di-electric constant (DC), and specific gravity. Different fuels are dyed for inspection identification purposes, and a fuel's color is the easiest to spot. Next, the DC is checked. "This is a measure of the gasoline's ability to conduct electricity," says Tim. "The test instrument used has a probe or a pair of concentric rings that are immersed in the sample, and a digital readout provides the data. Various mixtures of hydrocarbons have different DCs, and oxygen compounds raise them significantly." Lastly, inspectors measure the density of a fuel in relation to water, which is its specific gravity. "Water has a specific gravity of 1.000 at 60 degrees F. Racing gasolines usually fall in the range of 0.690-0.760, which means that they are between 69 and 76 percent the weight of water. Street gasolines usually fall in the range of 0.730-0.760." CHP