When someone told you "get the lead out," it usually meant your race carwas slow and you somehow had to find a way to make it faster. In the nottoo distant future, the term could lead to significant changes in racingfuels and engine modifications.

Environmentalists have recently stepped up their assault on auto racingand its use of lead-based fuels. With NASCAR as its primary target, agroup called "Clean Air Watch" sent a letter to the stock car racinggiant urging the abandonment of leaded fuels earlier this year.

"By permitting the continued use of lead, your organization may beputting millions of spectators and nearby residents at unnecessary riskof suffering serious health effects," stated the letter addressed toNASCAR chairman Brian France. "Because of the clear public healththreat, lead is being eliminated from gasoline throughout most of theworld. If Kazakhstan can eliminate lead from gasoline, why can'tNASCAR?"

The leaded fuel issue is one that probably won't go away--especially whenyou have watchdog groups tweaking the media--until NASCAR and othermotorsports sanctioning organizations begin using unleaded oralternative fuels. In 2006, for instance, IRL will begin using anethanol-based fuel in its race cars.

While there can be no question that lower lead levels in automotivefuels have had a positive effect on the environment, there is nooverwhelming evidence that the use of leaded fuels in NASCAR and otherforms of motorsports have caused significant health issues to theparticipants, fans, and communities surrounding raceways.

Still, it is inevitable because of emerging technologies and publicpressure from groups like the Clean Air Watch, that unleaded fuel willeventually find its way into engines in all forms of racing. In fact,research on unleaded racing fuels has been an ongoing process forseveral years at both the sanctioning body and grassroots levels.Several fuel companies already offer an unleaded racing fuel.

"We did some tests with a two-barrel Late Model engine using unleadedfuel a couple of years ago," said noted NASCAR engine builder TimmyPetty. "It was in the 12:1 compression range and it seemed like theunleaded fuel didn't hurt the power at all. I'm pretty sure that itwould work in a lower compression Late Model engine. The biggest problemyou are going to run into--whether it's a Late Model or a NASCARengine--is a spark knock condition. The engine is going to fire before itis supposed to. But again, in a 12:1 engine, I think it's going to bepretty borderline as to whether you are going to get into a spark knocksituation. If you get into a premature detonation situation, that's nota good thing. You're going to get hot spots and you're going to starttearing things up."

To understand today's debate over the use of leaded racing fuel, youhave to go back nearly 100 years to the beginnings of modern motoring.Early automotive internal combustion engines were underpowered andsluggish. In most cases, they also suffered from a severe knock duringthe combustion cycle.

Researchers at the time thought increasing the octane rating of the fuelwould cure many of these problems, and they concentrated their effortson rearranging the molecules found in petroleum to provide higher-octanegasoline.

General Motors was particularly active in this research after World WarI, conducting several experiments with octane. Originally, iodine wasthought to be a viable antiknock agent, but it proved to be animpractical additive in part because of the foul smell it produced.Eventually, researchers zeroed in on lead (Pb), or moreprecisely--tetraethyl lead (TEL)--as an additive to gasoline.

Early tests of TEL showed it significantly diminished knock in testengines. The discovery was hailed as a breakthrough. In 1923, GM, in ajoint venture with Standard Oil of New Jersey and Dupont, establishedthe Ethyl Gasoline Corporation. "Ethyl" as it was called, was addeddirectly to gasoline in liquid form at the refinery. By the late '30s,nearly 90 percent of all gas contained TEL.

In the '50s, scientific research began to uncover the debilitatingeffects of lead in products such as gasoline and paint. The UnitedStates Congress then got into the act, funding a two-year Public HealthService study on air pollution from cars in 1960.

Sensing the negative reaction and perhaps the health hazard suspected tobe generated by its product, General Motors divested itself of the EthylCorporation in 1962. Five years later, Congress passed the Air QualityAct/Clean Air Act, which authorized grants to individual state airpollution control agencies. The EPA issued its first reduction standardsin 1973, calling for a decrease of lead to one-tenth of a gram pergallon by 1986. The average lead content in gasoline in 1973 was 2-3grams per gallon, or about 200,000 tons of lead a year. By 1995, leadedfuel accounted for only 0.6 percent of total gasoline sales and lessthan 2,000 tons of lead per year.