What's lead got to do with it? | Fuel Tips

Staff
By Staff Writer
Oct 31, 2021 | Sunoco, Fuel Tips, Sponsored Content, Lead | Posted in Features | From the June 2019 issue | Never miss an article

Sponsored Content Presented by Sunoco.

Lead is no longer found in street fuels, but it’s still a popular ingredient in race gas. Time to explain. 

Why Lead in the First Place?

Tetraethyllead has been added to gasoline for nearly a hundred years. “It’s a very cheap and effective octane booster,” explains Zachary Santner, technical specialist at Sunoco Race Fuels. Just 6 milliliters of tetraethyllead, less than 0.2 percent by volume, is the difference between the 120- and 100-octane reference fuels used for octane testing, he continues. 

Why Did Leaded Fuels Go Away?

To meet the emissions standards introduced in the 1970s, car manufacturers began installing catalytic converters. Lead oxide, a byproduct of combustion, leaves a residue on catalytic converters, rendering them useless. Lead as a fuel additive quickly fell from favor. 

What Happened Next?

Less lead in pump gas resulted in lower octane ratings. As a response, engines were detuned. Remember the glorious muscle cars of the ’60s and early ’70s? That all ended around 1973.

Why Is Lead Used Today in Race Fuels?

The science hasn’t changed, as lead still remains an inexpensive, reliable, effective way to add octane to a fuel. Sunoco, for example, still relies on lead to boost octane above 105. These race-only leaded fuels can’t be used with oxygen sensors or catalytic converters, of course. 

What About Alcohol?

Fuels containing a high percentage of alcohol–think methanol–will, like high-octane fuels, also fight knock. However, fuels containing a lot of alcohol also require increased fuel flow, which requires specialized equipment. Small side note here: The lab tests done to determine a fuel’s octane rating can’t accurately score highly oxygenated fuels. “We developed this scale for measuring gasoline,” Santner explains, “and now we’re trying to use this scale to measure fuels that aren’t like gasoline–E85, for example. Finding consistent information on octane of highly oxygenated fuels is very difficult.”

Anything New on the Horizon?

Look for a new wave of unleaded, high-octane fuels. Santner says that Sunoco is about to add another high-octane unleaded formula called Evo 10 to its line of fuels. It’s 10 percent oxygen by weight and carries an octane rating of 105 (R+M)/2.

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Comments
frenchyd
frenchyd UltimaDork
10/28/21 11:34 a.m.

They do make a really good point about the difficulty of rating oxygenated fuels.  
     I'm found several sources that E85 has 100 octane and almost as many that claim 110 octane. 
 if we toss a little lead into E85 does that affect only the gas portion or the whole gallon?  

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
10/28/21 12:40 p.m.
frenchyd said:

 if we toss a little lead into E85 does that affect only the gas portion or the whole gallon?  

It actually makes the knock resistance worse, having tried some blends of E98 and various race fuels to make "E85" legal fuels.

Teh E36 M3
Teh E36 M3 UltraDork
10/28/21 12:49 p.m.

It's interesting to not address the health effects of lead in fuel- I'm sure that it was removed for that purpose as well? That is a question, to be clear. 

On a personal level, I have a riding friend who insists on fueling his bikes with 100LL from the local airport. It is so obnoxious (and noxious) to ride behind him. It was also shockingly stanky at the vintage races I attended a couple weeks ago. I dunno, count me out of the leaded fuel camp.

codrus (Forum Supporter)
codrus (Forum Supporter) GRM+ Memberand PowerDork
10/28/21 12:50 p.m.
frenchyd said:

     I'm found several sources that E85 has 100 octane and almost as many that claim 110 octane. 

IIRC the 110 rating is for pure ethanol.  E85 is a blend with gasoline and the allowable blend ratio can be anywhere from 50% ethanol up to 85%.  Obviously the percentage is going to affect the rating substantially, as is the rating of the gasoline it's mixed with.

 

codrus (Forum Supporter)
codrus (Forum Supporter) GRM+ Memberand PowerDork
10/28/21 12:55 p.m.
Teh E36 M3 said:

It's interesting to not address the health effects of lead in fuel- I'm sure that it was removed for that purpose as well? That is a question, to be clear. 

AIUI, no, the direct health effects of aerosol lead were not really a factor in the legislation.  Those effects are recognized now (there has been some interesting research correlating violent crime rates with the usage of TEL ~ 20 years before, when the people committing those violent crimes were babies), but at the time it was being driven by the goal of reducing smog and thus needing fuel that didn't destroy catalytic converters.

The general aviation industry really needs to get with the 70s and certify engines that can run on unleaded fuels.

 

Teh E36 M3
Teh E36 M3 UltraDork
10/28/21 1:19 p.m.
codrus (Forum Supporter) said:
Teh E36 M3 said:

It's interesting to not address the health effects of lead in fuel- I'm sure that it was removed for that purpose as well? That is a question, to be clear. 

AIUI, no, the direct health effects of aerosol lead were not really a factor in the legislation.  Those effects are recognized now (there has been some interesting research correlating violent crime rates with the usage of TEL ~ 20 years before, when the people committing those violent crimes were babies), but at the time it was being driven by the goal of reducing smog and thus needing fuel that didn't destroy catalytic converters.

The general aviation industry really needs to get with the 70s and certify engines that can run on unleaded fuels.

 

Wow- I really didn't know that it was driven from a smog perspective and not general health.  Also- I'm a pilot (but a commercial pilot) who is just dipping his toe into GA, god yes do they need to get with the times. I'm shocked that the GA industry (such as it is) hasn't embraced water cooled engines, like large displacement aluminum LS motors, for replacement and new construction. Crazy. Also, more importantly, stop with the 100ll.

frenchyd
frenchyd UltimaDork
10/28/21 3:05 p.m.
codrus (Forum Supporter) said:
frenchyd said:

     I'm found several sources that E85 has 100 octane and almost as many that claim 110 octane. 

IIRC the 110 rating is for pure ethanol.  E85 is a blend with gasoline and the allowable blend ratio can be anywhere from 50% ethanol up to 85%.  Obviously the percentage is going to affect the rating substantially, as is the rating of the gasoline it's mixed with.

 

Unless you buy E85 in cans or drums from racing fuel supplies.  There it's always 85% ethanol  without the absorbed water pump fuel has and the gas isn't whatever  but can be  real racing gasoline.  You pay about $1 a gallon more  but the quality is worth it plus it's about what you'd pay for pump grade 87 octane.  

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
10/28/21 3:08 p.m.

Why Did Leaded Fuels Go Away?

To meet the emissions standards introduced in the 1970s, car manufacturers began installing catalytic converters. Lead oxide, a byproduct of combustion, leaves a residue on catalytic converters, rendering them useless. Lead as a fuel additive quickly fell from favor.

Leaves a residue on catalytic converters...oh, and also poisons every square millimeter of our biosphere, that was kind of an issue:

https://www.mentalfloss.com/article/94569/clair-patterson-scientist-who-determined-age-earth-and-then-saved-it

frenchyd
frenchyd UltimaDork
10/28/21 3:29 p.m.
Teh E36 M3 said:
codrus (Forum Supporter) said:
Teh E36 M3 said:

It's interesting to not address the health effects of lead in fuel- I'm sure that it was removed for that purpose as well? That is a question, to be clear. 

AIUI, no, the direct health effects of aerosol lead were not really a factor in the legislation.  Those effects are recognized now (there has been some interesting research correlating violent crime rates with the usage of TEL ~ 20 years before, when the people committing those violent crimes were babies), but at the time it was being driven by the goal of reducing smog and thus needing fuel that didn't destroy catalytic converters.

The general aviation industry really needs to get with the 70s and certify engines that can run on unleaded fuels.

 

Wow- I really didn't know that it was driven from a smog perspective and not general health.  Also- I'm a pilot (but a commercial pilot) who is just dipping his toe into GA, god yes do they need to get with the times. I'm shocked that the GA industry (such as it is) hasn't embraced water cooled engines, like large displacement aluminum LS motors, for replacement and new construction. Crazy. Also, more importantly, stop with the 100ll.

The volume of engines used in general aviation is too tiny to certify  new engines.   Plus there are some die hards who insist reliability comes from old magneto's  not modern electronics.  
Who's going to pay for the fight required to get the entrenched out?  
  Modern composition airframes and wings water cooled engines. Etc the sky's could get as crowded as the highways are. 

dr_strangeland
dr_strangeland GRM+ Memberand Reader
10/28/21 10:17 p.m.

Xylene is 117 octane, toluene is 114 octane.

You can get a gallon of xylene at home depot for $22. Add that to four gallons of 92 pump gas and you should be around 97-98 octane. Without lead.

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