Buying 100LL

[John Galt]

How difficult is it to buy 100LL aviation fuel? I assume you just don't wheel into an airport, swipe your card, and fill a gas can. Anyone with their own small planes (or pulling tractors) buy it for non-commercial use?

 

[bgreer75]

That's how I buy it....just like at gas station. It is a small airport.

 

[TERRY HAYES]

that is how we buy it also also at a small airport

 

[John Galt]

Thanks. There's a few around here somewhere. I'll check them out.

 

[Kelly N]

St almost all local small airports, I simply do as you stated. Take my fuel can to the pump and enter the card and information it asks and pump your fuel. Its simple.

 

[Dblair]

hope it's not a real high compression engine -100LL is not 100 octane as we rate it for pump gas (R+M/2). It is actually ~96 octane by that measure.
-Quality and consistency is better than pump

 

[Anonymous-0]

100LL is for airplanes at altitude, yes it burns in a tractor but there are better options

 

[buickanddeere]

Credit card or debit card and an approved gas can. Self serve at the local airport.
Price is right on 100LL.
Octane valve does vary if the mixture is rich or lean.
As for compression pressure on natural aspirated spark ignition engines. That , mechanical compression radio and valve timing vary octane requirements dramatically.
As for compression pressure in an open cycle Brayton Cycle reciprocating engine.it"s the ratio between the compression pressure and expansion pressure along with the working area that makes "power ".
There comes a point with the extra heat and pressure on the compression stroke on a short cammed, high mech ratio engine. Runs into the point of dimnishing returns .
There can be more "power" in that same high mechanical compression ratio. With longer cam duration to improve breathing and lower compression pressure.
More isn"t always better. Not unusual to hear a contest between who runs the highest mech ratio, highest comp pressure , most spark advance etc.

 

[chevytaHOE5674]

UP here there are a few gas stations that sell 100LL at the pump for people to use in their race cars, and snowmobiles.

 

[John Galt]

I looked up 100LL and it showed 100.5 MON, 103.2 RON, and 101.5 AKI (R+M/2). I also learned that it is very good when MON & RON are close together.

 

[John Galt]

Thanks guys! I looked at my local small town airport and I can buy it at the pump with a credit card 24-7 for $5.25/gal. I was bouncing around ideas of 100LL or E85 in a smaller 10:1 engine. My impression so far was E85 is a little less octane (R+M/2) and cheaper but a little more tempermental. Yeah, I could just go buy the good stuff, but curiosity kills me.

 

[John Galt]

Oh probably 10:1 min 10.5:1 max.

 

[John Galt]

This will be a 10:1 mechanical ratio. Probably a little over 200# compression at cranking pressure if a stock cam was used, but I'll probably have a hair more duration and lift built in than stock. I know that's a little vague on details, but I'll know more as it comes together.

 

[Dblair]

I'm sticking with 110 for 10.5 to 1 comp. I'm just putting the facts up .

 

[John Galt]

We're running 110 in our bigger 10:1 engine now and liking it.

 

[buickanddeere]

All other factors the same. The larger the combustion chamber/displacement. The more octane is required.
If the combustion chamber is open instead of having a quench . The engine will require higher octane.
Having that piston top 5-20 thou from the cylinder head somewhere . Introduces squish and turbulence that interrupts flame front collision.

 

[778899m]

Piston 5 thou from the head,think again,bearing lash and growth at rpm will cause contact.If you do not measures chamber volume with a beret,you do not know the ratio.

 

[buickanddeere]

5-20 thou hot. So cold is roughly 30-50 thou cold.