Can You Run AV Gas With Any Carb ?

[LakesOnly]

remember algebra? In this case we call it stoichiometry. Now, the math.
if you ad 1 gal 100 oct to 1 gal 92 oct you'll have 2 gals of 96 octane rating fuel. (etcetera. -LO) Wish it were that easy, but I don't think it is.
The 100 octane rating for the AvGas is a Motor octane number, while the 92 pump gas octane number is likely a Research + Motor / 2 (R+M/2) octane number, which would result in less than 92 Motor octane. So with this much in mind, one cannot make a 50/50 blend of the two fuels (with different type octane ratings) and thereby achieve a "mid-way average" octane rated fuel.
To further compound the issue: I once read a laboratory study that took place back when we all used to be able to purchase both leaded and unleaded pump gas at the pump. It was found that if the unleaded fuel already had a 92 octane rating without any lead in it, adding a splash of leaded regular would kick up the octane rating of the fuel more than what a simple math calculaton would suggest, meaning that there is chemistry at work here as well. I'm afraid I don't remember the leaded/non-leaded fuel proportions in the report, but I recall it was very little, like a few of gallons leaded regular added to a tankful of unleaded. I don't know that the AvGas will work this way exactly, but I do know that the last leaded pump gas had 1/10 gram/gallon in it and that AvGas has twenty times this amount (2 gr/gal).
LO

[rrrr]

Wish it were that easy, but I don't think it is.
The 100 octane rating for the AvGas is a Motor octane number, while the 92 pump gas octane number is likely a Research + Motor / 2 (R+M/2) octane number, which would result in less than 92 Motor octane. So with this much in mind, one cannot make a 50/50 blend of the two fuels (with different type octane ratings) and thereby achieve a "mid-way average" octane rated fuel.
To further compound the issue: I once read a laboratory study that took place back when we all used to be able to purchase both leaded and unleaded pump gas at the pump. It was found that if the unleaded fuel already had a 92 octane rating without any lead in it, adding a splash of leaded regular would kick up the octane rating of the fuel more than what a simple math calculaton would suggest, meaning that there is chemistry at work here as well. I'm afraid I don't remember the leaded/non-leaded fuel proportions in the report, but I recall it was very little, like a few of gallons leaded regular added to a tankful of unleaded. I don't know that the AvGas will work this way exactly, but I do know that the last leaded pump gas had 1/10 gram/gallon in it and that AvGas has twenty times this amount (2 gr/gal).
LO
Oh shit, did someone mention Chemistry?
The only thing I know about that relates to the various studies and experiments I have done with ethyl alcohol....... :crossx:

[Kindsvater Flat]

I've been working on something. Let me upload it and see if it works.
All I had were the numbers and had to make a chart using table and cells. Try this and see.
Fuel Chart (http://www.schoutenranch.com/fuel/fuel2.htm)

[centerhill condor]

Summary of Grade-Specific ASTM D 910 Requirements
. Grade .
Property 80 100 100LL ASTM Test Method
Knock rating, lean mixture
Motor method octane number,
min 80.0 99.5 99.5 D 2700
Knock rating, rich mixture D 909
Supercharge rating:
Octane number, min 87.0
Performance number, min 130.0 130.0
Tetraethyl lead concentration D 3341 or D 5059
mL TEL/L, max 0.13 1.06 0.53
g Pb/L, max 0.14 1.12 0.56
Color Red Green Blue D 2392
Dye content:
Blue dye, mg/L, max 0.2 2.7 2.7
Yellow dye, mg/L, max None 2.8 None
Red dye, mg/L, max 2.3 None None
For boating purposes, I think all that (R+M)/2 stuff evens out. If Chevron gives themselves a 1/2 point margin for error on the low side (min), me thinks we'll be allright given the other variables; timing, atmospheric pressure, relative humidity, air/fuel mixture etc. Now, if we're gonna be sending a man to the moon with our bucket chemist mix...you'd wanna take all that other information into consideration and buy straight race gas.

[AzMandella]

I've been working on something. Let me upload it and see if it works.
All I had were the numbers and had to make a chart using table and cells. Try this and see.
Fuel Chart (http://www.schoutenranch.com/fuel/fuel2.htm)
Your chart for 110 oct + 92 is wrong.If you mix 1 gal to 1gal and 3gal to 3 gal it should be the same octane.

[Kindsvater Flat]

Your chart for 110 oct + 92 is wrong.If you mix 1 gal to 1gal and 3gal to 3 gal it should be the same octane.
Like I said, I just had the numbers. I didn't make the numbers just the chart.

[OverKill]

If you do run AV gas only get it at the airport. They have to do tests on the fuel every 24 hours, You just don't want an aircraft falling out of the sky from engine stall by bad gas. Also if you run you boat at Big River (Parker AZ ), don't buy the AV gas at Parker Oil. I have had a bad fill before by them.

[Sleek-Jet]

They have to do tests on the fuel every 24 hours
No they don't, unless you figure sumping the tanks on the truck as a "test". Now it is true the filters and what not are probably changed more often at the airport, and the fuel farm is probably in a little better shape... but really, airports don't handle their fuel much differently than any place else.
I would buy it from the airport just to help the FBO out. Contrary to popular belief, most places are happy to sell as much gas as possible... doesn't matter if it goes in an airplane, a can, or a boat.
Jet fuel is mil-por tested more often, but only a few people are running turbines in their boats...

[GofastRacer]

If you do run AV gas only get it at the airport. They have to do tests on the fuel every 24 hours, You just don't want an aircraft falling out of the sky from engine stall by bad gas. Also if you run you boat at Big River (Parker AZ ), don't buy the AV gas at Parker Oil. I have had a bad fill before by them.
No they don't have to do tests every 24hrs, and FYI Parker Oil is the distributor for AV gas and that's where the airport get's it from, I been getting AV gas from them for ages and it's always the good stuff, you may have had a problem elsewhere???..

[Norseman]

FYI
http://forums.everything2stroke.com/...-gasoline.html
Contrary to popular belief this isn't 100-octane fuel. Aviation fuels are rated on an ASTM Lean/Rich performance number system. 100LL is rated at 91/96 By comparison; Unocal Leaded race gas that is used in lots of spec fuel racing classes has performance number of 112/160. 100LL is closer to 91 octane (MON); by comparison VP C12 is rated at 108 (MON).
For our purposes avgas has a couple of problems:
1) The 90% boiling point for 100LL blue avgas is set at 275 degrees F, which in an engine that turns over 7000 rpm will likely make less power than a fuel that has it's 90% point lower. Pump gas has similar problems, but most good race gas will have 90% point MUCH lower. As an example Phillips B32 has a 90% boiling point around 235 degrees F and VP C12 has a 90% boiling point around 220 degrees F.
2) Depending on the refiner 100LL can have fairly high aromatic hydrocarbon content, in the 30% by weight range. This level of aromatics will tend to make the throttle response mushy and flat in applications that see big throttle opening transitions on a regular basis. It's similar to what happens when you dump a lot of toluene based octane booster in your fuel. Throttle response becomes a distant memory.
3) The vapor pressure and distillation curve of avgas just doesn't seem right for our purposes. The distillation curve of a fuel determines to a large degree the warm-up, transitional (on & off) throttle response, and acceleration characteristics of an engine.
Here's the simplified version:
A fuels distillation curve designates the maximum temperatures at which various points between 10% and 90% of the fuel will be evaporated as well as the maximum end point temperature. So for any engine/air temperature combination there is a minimum volatility that is required for proper running. As you probably know gasoline is made up of different hydrocarbons, with different boiling points. By combining these hydrocarbons together you get a distillation curve. Some hydrocarbons (light ends) boil off at low temps while some do at much higher temps. Depending on the intended application, a petrochemist will blend hydrocarbons to get a curve that matches the rpm range, temp, altitude, and acceleration characteristics for the application. The problem with avgas as a race fuel is the fact it is blended for an application where acceleration and throttle response are not high priorities. If you think about the average light airplane application, you're talking about a fairly low compression engine that runs in a fairly narrow rpm band, and is rarely called on to provide the type of transitional throttle response that a high rpm, acceleration critical application like motocross does. What's more important to the avgas designer is controlling mixture strength by eliminating the possibility of vapor lock and icing while making sure that light end hydrocarbon fractions don't boil off too early. The lowered rpm ranges used in these engines allow them to push the boiling point up on the upper end as well. As you can see, by using straight avgas or by mixing various types of fuel together you are modifying a number of important fuel design parameters. You may hit on a combination that works well, but more likely you'll have an engine that doesn't detonate, but doesn't accelerate very well either. So avgas is SAFE, but not a very good choice. The high paraffinic hydrocarbon content of 100LL makes a very good base stock if you want to play back yard petrochemist, and I believe this is how some of the smaller race fuel blenders start out. I can tell you from experience that it's a pain to document and test various changes unless you have a lot of time and patience, so trying to come up with your own Super Fuel is probably more trouble than it is worth