Gasoline for Fuelies

[Bruce B.]

Re: Gasoline for Fuelies

Concerning using 100LL in engines other then in cars & trucks;
The fuel guy at the local airport mentioned using 100LL when storing powered equipment such as mowers, tractors, snow blowers and any other internal combustion powered stuff.
I do that over the winter (except the snow blower) and the fuel does not go bad. It will actually stay fresh for a few years.

[David K.]

Re: Gasoline for Fuelies

I just love aviation fuel! I don't really need to run it 100%, but mix it some what. Just a few gal. to a tank of standard pump gas goes a long way to preventing vapor lock and gummed up tanks and other fuel system parts. I was fortunate enough to have a tank full of LL when I parked the '62 for a quick redo that ended up taking 15yrs. When I turned my attention to the furl tank, all the LL had evaportated, but it left no varnish at all. It is also a great fuel to keep in your home generator, that hopefully doesn't see much use. At my local airport, they had a gas powered post hole digger that had not been used, they thought anyhow, for over 12yrs. Naturally at the airport, most gas engines run there on LL. This post hole digger still had this old gas in it and started on the 2nd pull. One thing they did say is that exhaust systems, if you run this fuel straight, will burn out earlier than with pump gas. They claim that the fuel will "after" burn somewhat in the muffler. Regardless, I do love the fuel and use it in all engines that are stored for the winter, though it is usually blended with the gas that is already in the tank. I regret though, that I have no experience with it in a fuelie.

[Carl B.]

Re: Gasoline for Fuelies

The main issue with 100LL is there is no tax on the fuel

[Jim T.]

Re: Gasoline for Fuelies

check out local unattended airports that have self-serve fuel to fill your cans.

[Bruce B.]

Re: Gasoline for Fuelies

After taking a long ride yesterday I stopped at my normal Shell station and filled up with 93 octane. There were no stickers on the pumps indicating added ethanol. I asked the cleck and she didn't know if there was ethanol in the gas (she didn't know what ethanol was...)
I later checked a ethanol free web site and I found out that Ohio does not require disclosure (such as labels on the pumps) if ethanol is added to the gasoline. This is common in many states.
I guess the ethanol supporters have gotten to the Ohio politicians, as usual.

[William F.]

Re: Gasoline for Fuelies

I remember reading back when leaded high octane pump gas was first discontinued that you get more octane boost by mixing 1 part 100LL aviation fuel or racing gas with 3 parts MID grade unleaded pump gas than if you mixed with 3 parts unleaded premium.Is this true-not wanting to debate opinion of need for octane higher than 93, which is another subject. Some outboard motor copanies state that pump premium is harmful to their motors compared to premium. Not suggesting we run pure 89 octane but wonder about effect of additives in today's premium(not counting ethanol, if present).
Thanks

[John H.]

Re: Gasoline for Fuelies

I remember reading back when leaded high octane pump gas was first discontinued that you get more octane boost by mixing 1 part 100LL aviation fuel or racing gas with 3 parts MID grade unleaded pump gas than if you mixed with 3 parts unleaded premium.Is this true-

Bill -

I don't know, but it doesn't sound logical. Mid-grade gas doesn't exist as a distribution commodity - it's mixed in the retail gas pump, 50-50 equal parts regular and premium. Stations only have two underground tanks for gasoline.

[William F.]

Re: Gasoline for Fuelies

Hate to disagree with John Hinckley, but-In some areas mid grade is a separate refinery grade and is stored in a 3rd tank at service station. I verified this with my local Shell jobber and saw the 3 tank filler covers with different coding at the station where true mid grade is available.
Bill Ford

[Duke W.]

Re: Gasoline for Fuelies

Avgas uses the "Aviation Method" for octane rating, which is about the same as the Motor Method to yield Motor Octane Number (MON), and RON (Research Octane Number) is typically 8-10 higher than MON, and this difference is called "sensitivity".

PON = (RON + MON)/2, so 100 LL avgas is about equal to 104 PON.

Any original engines or rebuilt engines to OE specs , except L-88/ZL-1, that detonate on pump premium should not require more than about 25% 100LL with 93 PON pump gas to quell any detonation, and most should run okay on pump premium alone, especially small blocks. Big block have somewhat more "octane appetite".

The octane of the blend is approximately the weighted average, so:

.75(93) + .25(104) = 95.76 PON, which is right at about 100 RON.

The typical range of pump preimums back in the sixties was 98-100 RON, and "super premiumus" were a little over 100 RON

Duke

[Larry M.]

Re: Gasoline for Fuelies

Here in the DEEP SOUTH we have three distinct underground storage tanks for the three different grades of gasoline: 87, 89, and 93. It's not like the old SUNOCO 100 and 260 grades of old, where the intermediate grades were blended at the pump.

I am not certain how the various gasoline grades are manufacturered in the refinery.....it is possible that only two main grades and produced and then intermediate grades are blended for distribution. I would have to ask one of the petroleum engineers what is currently being done in the plant(s).

Regarding gasoline octane. There was some discussion many years ago (10-15 years) about how blending of leaded premium gasoline (or any leaded gasoline) with unleaded gasoline COULD produce a slightly higher octane than would typically be calculated FOR THE BLEND. This was due to the increased synergestic effect of the tetraethyl lead on the lower octane grades. If this occurs, it is a very slight difference.....not worth a lot of additional discussion. Maybe an extra 0.1 or 0.2 octane boost versus the calculated octane number.

Larry

[Duke W.]

Re: Gasoline for Fuelies

Regarding gasoline octane. There was some discussion many years ago (10-15 years) about how blending of leaded premium gasoline (or any leaded gasoline) with unleaded gasoline COULD produce a slightly higher octane than would typically be calculated FOR THE BLEND. This was due to the increased synergestic effect of the tetraethyl lead on the lower octane grades. If this occurs, it is a very slight difference.....not worth a lot of additional discussion. Maybe an extra 0.1 or 0.2 octane boost versus the calculated octane number.

Larry

Let me explain this in a bit more technically correct terms.

TEL has a marginal decreasing effect on octane improvement, which means each additional increment of TEL produces an ever decreasing increase in octane.

That's why when mixing a blend of unleaded and leaded fuel, the weighted average number you compute is approximate.

For example, regardless of what octane measurement method is used, if you mix a 50/50 blend of 96 octane with the same base stock gasoline enhanced to 100 octane with TEL, the resulting blend should be slightly higher than the weighted average of 98 because the increase in octane to the 96 octane part from the now half concentration of TEL is more than the decrease in the 100 octane part.

So the resulting blend may be 98.1 or 98.2, or maybe 98.3, but fretting over tenths of octane points is "pointless".

If someone has an engine that detonates on pump premium the first thing to do is look at changes to the spark advance map - reducing initial timing, slowing the centrifugal, or a combination of both - to eliminate the detonation.

If the spark advance map has to be retarded so much that significant performance is lost or the engine runs hot, the only other choice other than lowering the CR is to find a blend of high octane fuel (avgas or race gas) that quells the detonation, and from a practical standpoint, one has to find the minimum amount of higher octane fuel that has to be blended with pump premium to tame any detonation.

It's best to start with a small amount - say a 10 percent avgas/race gas and increase as required, and as I said before, if the engine is OE or OE equivalent rebuilt, it should not require more than about 25 percent.

In fact, very few OE or OE equivalent rebuilt engines require more than pump premium, and most of those are big blocks.

Duke

[John H.]

Re: Gasoline for Fuelies

Hate to disagree with John Hinckley, but-In some areas mid grade is a separate refinery grade and is stored in a 3rd tank at service station. I verified this with my local Shell jobber and saw the 3 tank filler covers with different coding at the station where true mid grade is available.
Bill Ford

Bill -

It must vary regionally to some extent; there's only one refinery/prime distribution point (Marathon) in the entire state of Michigan, and they only have two base stocks.

[Joe C.]

Re: Gasoline for Fuelies

I remember reading back when leaded high octane pump gas was first discontinued that you get more octane boost by mixing 1 part 100LL aviation fuel or racing gas with 3 parts MID grade unleaded pump gas than if you mixed with 3 parts unleaded premium.Is this true-not wanting to debate opinion of need for octane higher than 93, which is another subject. Some outboard motor copanies state that pump premium is harmful to their motors compared to premium. Not suggesting we run pure 89 octane but wonder about effect of additives in today's premium(not counting ethanol, if present).
Thanks

Misleading advertising, but true when expressed as a per-cent increase. e.g.:

Convert all octane numbers to PON

a). 3 parts 89 octane mixed with 1 part 100LL (104) = 4 parts 92.75 octane

b). 3 parts 93 octane mixed with 1 part 100LL (104) = 4 parts 95.75 octane

the percentage octane increase obtained in "a" is:
[92.75 - 89]/ 89 = 4.21% increase

the percentage octane increase obtained in "b" is:
[95.75 - 93]/93 = 2.96% increase

[Joe C.]

Re: Gasoline for Fuelies

Not all states can sell ethanol free gasoline. Here is a comprehensive listing, with addresses, on a state-by-state basis:

http://www.examiner.com/examiner/x-4824-Tampa-Sports-Car-Examiner~y2010m1d23-List-of-ethanol-free-gas-stations

[Paul Y.]

Re: Gasoline for Fuelies

Joe, Thanks a million for that web site. I'm looking forward to filling up tomorrow with no ethanol. I filled up last summer in Gunnison , Co. and could tell a difference. Again, thanks a lot. Paul