Fuel 101: Octane, SG, VP, Major Components, etc..

[emsvitil]

They're working on 100UL.

94UL is 100LL without the lead

[MadBill]

That should be fun for the engine manufacturers; having to re-certify all their engines.

[emsvitil]

They want 100UL to be a drop-in replacement. No recertification.

[MadBill]

That sure didn't work for the US auto industry back in the early seventies...

[Kevin Johnson]

http://www.aviationconsumer.com/issues/ ... 234-1.html

[Turborick]

1. I don't understand how TEL works to increase octane?

At the temperatures found in internal combustion engines, (CH3CH2)4Pb decomposes completely
into lead and lead oxides as well as combustible, short-lived ethyl radicals. Lead and lead oxide
scavenge radical intermediates in combustion reactions. Engine knock is caused by a cool flame,
an oscillating low-temperature combustion reaction that occurs before the proper, hot ignition.
Lead quenches the pyrolysed radicals and thus kills the radical chain reaction that would sustain
a cool flame, preventing it from disturbing the smooth ignition of the hot flame front. Lead itself
is the reactive antiknock agent, and TEL serves as a gasoline-soluble lead carrier

2. If you want more out of your fuel, then you might play with small amounts of Nitro additions! BUT very carefully!!

A number of years ago, John Copeland, of Fox Valley Karting , using a dyno at Purdue University,
performed a series of performance tests using various amounts of various "power additives" in a go-kart engine.
His white papers had become the most useful documentation available at that time.

John's findings negated several popular misconceptions yet supported others as being valid.
Nitromethane did produce power improvements but only when substantial amounts (+30%) were
added to gasoline. But nitromethane is not very soluble in gasoline so a co-solvent (methanol) was
used with nitromethane. Nitropropane, on the other hand was soluble in gasoline but did not
produce any power improvement. John warned racers that for every engine there existed a
tuning window of fuel blend, mixture, and timing that must be optimized.

3. True story! I was pumping gas into my corn-popper filling it up, (getting ready for tomorrow's commute), one Sunday morning years ago and I swear, the dammed fumes coming off of my tank smelled just like cheap used, "paint thinner"!!

Good nose!
Paint thinners for lacquer, enamel, epoxies, do share several components also found in automotive fuels. i.e. toluene, xylene, ethanol, naptha, MEK, and others. Not all paint thinner solvents are suitable for automotive use since they can negatively impact fuel system polymers.

I figure the refineries have a base stock and as they purify it, they remove various other stuff that needs to be blended back into their fuels mixes to use them up as well as to sell them so they can make a profit! This is why fuel blends change all the time, it is a balancing act!!

Absolutely correct. Base stocks vary considerably based on crude oil source and type. Useful components that can be sold at higher prices are removed, and low value components are blended into fuels which are low margin but high volume products.

For those who might be interested, I have a paper that I wrote on race engine fuel tuning for SCCA and Formula SAE that I could email if anyone wants it. I also have John Copeland's fuel papers as well.

David I would be interested in those papers, I will PM you my email

[steve cowan]

http://www.aviationconsumer.com/issues/ ... 234-1.html

thanks for the link KJ,looking like they are no closer to unleaded avgas,they want to have their ducks lined up correctly before saying ''yep good to go'' put the planes in the sky !!!

That sure didn't work for the US auto industry back in the early seventies...

Hey Bill,i am thinking DEJA-VU what are your thoughts?

[Truckedup]

That sure didn't work for the US auto industry back in the early seventies...

The US auto manufacturers did not do what was required from known techniques at that time.. As always, especially GM, they cheaped out and the consumer paid the price.

[MadBill]

http://www.aviationconsumer.com/issues/ ... 234-1.html

thanks for the link KJ,looking like they are no closer to unleaded avgas,they want to have their ducks lined up correctly before saying ''yep good to go'' put the planes in the sky !!!

That sure didn't work for the US auto industry back in the early seventies...

Hey Bill,i am thinking DEJA-VU what are your thoughts?

The same!

[NewbVetteGuy]

...

Thanks David! I was hoping to have some major myth busting happening on this thread and was hoping that you'd chime in.


Adam