In 1996, the EPA's Clean Air Act banned the sale of leaded fuel for usein on-road vehicles but stated leaded fuel could continue to be sold foroff-road uses such as race cars, aircraft, farm, and marineapplications.

This was especially good news for NASCAR, which needed a high-octanefuel to run its high-compression engines in the 8,000-10,000 rpm range.The Sunoco 110 Leaded Racing Gasoline used in NASCAR Nextel Cup, Busch,and Truck Series is touted on the company's Web site to "make stock carsrun better."

"NASCAR had to go to the 12:1 compression rules about two or three yearsago because some engine builders were pushing the compression to as muchas 18:1 in the plate motors," stated Petty. "Obviously, unleaded fuelwouldn't have worked in those engines. But if we went back to the 9:1compression engines that we used to run in the NASCAR Busch and TruckSeries, I think you could make the switch to unleaded fuel without toomany problems. You could certainly do it with a mix of unleaded and alittle leaded fuel to begin with."

Petty's longtime experience as a racing engine builder gives him ahands-on perspective on the unleaded fuel situation. The son of famedNASCAR engine builder Maurice Petty, Petty has produced hundreds ofengines across a wide spectrum of racing divisions. Today, Maurice Pettyand Associates offer engine lease programs to all three top NASCARdivisions as well as produce USAR Hooters Pro Cup Dodge engines forSteven Wallace, Chevrolet powerplants for Joe Gibbs Racing diversityprogram, and Ford short-track engines for the Belnavis/Roush diversityinitiative.

"Some of the short-track engines we build use different versions of theSunoco 110 racing fuel that NASCAR uses," said Petty. "That's what wedyno everything with. I don't think we'd have much of a problemswitching those short-track engines over to unleaded fuel. In that typeof engine, that wouldn't be a big switch."

Of course, having the right components, especially in NASCAR where thedemands of 500-mile events put engines to limits not seen at the weeklyracing level, would make the transition to unleaded fuel a lot easier.

"If someone was still running stainless steel valves, I think you couldhave some problems in the valvetrain using unleaded fuel," said Petty."In NASCAR, you're allowed to run titanium valves, so I don't thinkthere's going to be a problem in the valvetrain. Also, the new berylliumcopper valve seats are so much better than the old cast seats. They arevery forgiving alloy seats that are hard enough to survive theperformance demands of almost anything we throw at it."

Petty also added that as NASCAR develops new engines for competition,future configurations could easily lend themselves to the use ofunleaded fuel.

"The 'Engine of the Future' concept--smaller cubic inches, a smaller boreand stroke--could use unleaded fuel, especially if they lower thecompression to let's say 9:1. I hope I'm not wrong here, but I thinkwith the new ring packages and the smaller, lighter weight stuff we'realready using, you could reduce the octane some and get away withrunning unleaded fuel in the new engines NASCAR is talking aboutintroducing down the road."

For its part, NASCAR has also been conducting unleaded fuel tests forsome time, but according to NASCAR spokesperson Ramsey Poston, thesanctioning body is still searching for answers.

"NASCAR has looked into and will continue to look into making the switchto unleaded, but has not been able to find an alternative additive tolead, which lubricates engine valves," said Poston earlier this year."Without being able to keep the valves lubed, the engines don't work aswell."

Petty believes NASCAR is serious about finding a solution to theunleaded fuel debate. He also sees a secondary advantage to NASCARengines running on lower octane unleaded fuel.

"I think it would be pretty cool for NASCAR to come up with some enginerules that would allow you to run the same unleaded fuel that everyonecould buy at the pump," said Petty. "To say that you can buy the samegas at the pump would be a very cool thing for the sport."

Assuming Petty is correct and new generations of NASCAR engines caneffectively burn unleaded fuel, groups like the Clean Air Watch willhave to find other targets. Those targets will most likely include theweekly short-track racing industry. Again, Petty thinks the problem canbe overcome.

"I don't believe the weekly racers are going to have much of a problemgoing to unleaded fuel," said Petty. "I would think most of these guysare already running a mixture of unleaded and leaded fuel, somethingwith just a splash of racing gas in it to get the octane up. They wantthe octane, not the lead, for a little extra power. There's actuallysome high-test unleaded fuels on the market now that have an octanerating in the 96 range. If you can get the right octane in an unleadedfuel, you wouldn't have a problem."

Which brings us right back to the situation the automotive industryfaced nearly a century ago--finding the right gasoline additive that willboost octane and performance.

"I think it's just a matter of time before we're going to have to berunning unleaded fuel in all race cars," said Petty. "I'm not sure whatwe can do to take the lead out of racing fuel and still be able to boostthe octane. I guess we'll have to get back in our chemistry books tofind that out."

Unleaded in Racing

Several fuel companies already offer options for unleaded racing fuels.Many of the applications are street-legal in most states and have beendesigned with the electronics of modern cars in mind.

Sunoco has the GT100 Unleaded and GT Plus Unleaded fuels in its family.The GT Plus has an antiknock index of 104, which is one of the highestof the unleaded racing fuels. It can be used in engines that have up to12:1 compression, which seems to be the breaking point with today'sfuels.

Here's a head-to-head comparison of Sunoco's Standard Lead Fuel with theGT Plus Unleaded.

Specific Gravity.725.746
Antiknock Index110104
ColorPurpleLt. Blue

In the VP Racing Fuels family, there are a number of options. Many ofthese options are well suited for motorcycle or marine use, but thereare those that work well in the automotive realm.

The company is presently developing the StreetBlaze brand, which isavailable for street applications of higher octane unleaded fuels. Thehighest street-legal octane to date is 103.

For off-road usage such as motorsports, the 100-octane C10 is anon-oxygenated racing gas that is used in SCCA and IMSA classes.Motorsport 100, which is orange in color, is oxygenated with ethanol.There is also a Motorsport 101, similar in color but a notch higher inoctane. The unleaded Motorsport 103 can provide power and protectionsimilar to some leaded racing fuels. VP also has a specialty unleadedMotorsport 109, which can be run in engine compression up to 13:1. The102-octane CSP fuel is used in the Toyota Atlantic series while the SR1fuel is offered for those in the SCCA with engine compression less than10:1.

Sunoco Race Fuels VP Racing Fuels