100ll Avgas Ok to run?

YZBrad

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Hey guys, hows it going? Ive read article saying why we shouldn't run aviation fuel in our cars, but they never give a real good explaination as to why we can't. On the other hand Ive talked to many racers (mostly drag racers and motorcycle racers) and they run it no problem.

Can any of you guys shed some light on this topic? I know the lead will mess with the o2 sensors, and you cant run it if you have a cat, but the application I am thinking of has neither. A buddy of mine has a 500ci 12:1 Camaro that runs on 110, but at $10/gallon, its pretty expensive to run in it all the time. It should run on 100 octane, just around town, no hard passes, and at $5/gallon, you cant beat the price for 100 octane low lead aviation fuel.

My only concern is the fuel is designed to run in very thin air, so that may play a part in how it behaves on the ground. Anyways, am I way off the mark here, thinking we could run that fuel in his Camaro?
 
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From an old thread:

http://www.race-dezert.com/forum/newreply.php?do=newreply&p=47596

Hi John,



Here is some real world experience that should answer your questions. As I think you are aware, Chris Wilson and I raced my truck to La Paz last year. I drove the truck about 140 miles from the race shop at Chris’ house in El Cajon, CA to Ensenada, Mexico and then raced it 1017 miles to La Paz. I used 185 gallons of 100LL (Low Lead) Aviation Fuel that I bought at the Ramona Airport for our first four Pit Stops and 90 gallons of Union 76 Race Fuel for our last three Pit Stops. Then I drove the truck home from La Paz to El Cajon using 93 Octane PEMEX that was readily available but not at all the PEMEX stations. At one stop I had to use regular unleaded, I don’t remember the Octane rating, but only used 20 gallons mixed with what was left in the 60 gallon fuel cell. The truck got just under 4MPG racing and 7MPG on the way home (80 to 90 MPH) and ran perfectly. It has since raced two 250 miles races and seen another 250 test/play miles all on 100LL. The only problem experienced was one very dirty fuel filter with water in the catch bowl after the 1000+ mile run on PEMEX.



The motor is a Ford 351W 408CI Stroker, originally built by Leon Patton and then Jim Horn, and put out 530 HP at 12.8 to 1 compression ratio on VP C-12. We rebuilt and detuned it, dropping the compression ratio to 10 to 1 and changing the cam just before the 1000 and broke it in on the drive to Ensenada. I had it Dyno’d after the Baja 1000 running on 100LL and it put out 430 HP from 410 cubic inches.



Your Blazer will run really well on 93 Octane PEMEX, just make sure you have a good fuel filter system. The 100LL contains Lead and is not good for your Cat and O2 sensor.
 

DRIVE Jon

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What Ramsey said.

100LL is very high-quality gas....with very low water content. It is leaded...but won't matter if you don't have emissions stuff.

Other than some blue dye...and a different smell....smells more sour....its just good old gas. No special formulation for burning better at altitude.

(the dye is to desinguish from other grades of aviation fuel...MAKE SURE IT LOOKS BLUE...it is faint...but in a clear cup held up to something white...it should have a blue tint...which means 100LL...... not red!= 80 octane)

Jon
 

jowoog

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thought it had de-iceing agents in it . i ran it along time ago in an old non emission car . no problem . smelled cool .
 

scottm

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It works great. Its more consistant, as the formula doesnt change with the time of year. I heard somewhere that engine makers like B&S use it for testing due to its consistancy. I ran it in my dirt bikes mixed 50/50 with pump gas, and I put it in my rv over the hot summer to reduce gas breakdown in the tank. Race gas sellers claim it goes bad faster, that it harms seals, etc - all bullcrap. It is designed to be longer lasting and less harmful to anything and everything in an engine and fuel system, obviously due to the potential proplems when airplanes stop running!

It will ruin catalytics. And it is slower burning, so it will make less power with low compression or less ignition timing.
 

Co-Dog

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If you do your driving above 5000 feet where the air pressure and oxygen content become a factor in the way that fuel burns, Avgas is just what you need.

Mixing with pump gas probably does produce desirable results in some applications. If you keep doing it though, you will be rewarded with burnt exhaust valves, GUARANTEED!! If the engine wasn't built to run on high octane, you aren't doing it any favors.
 

YZBrad

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If you do your driving above 5000 feet where the air pressure and oxygen content become a factor in the way that fuel burns, Avgas is just what you need.

Mixing with pump gas probably does produce desirable results in some applications. If you keep doing it though, you will be rewarded with burnt exhaust valves, GUARANTEED!! If the engine wasn't built to run on high octane, you aren't doing it any favors.

Would running richer jets prevent the exhaust valve damage? It does need the octane, the engine runs on 110 when racing, but it will run on 100 around town, and it would be much more economical.

I appreciate everbodys input, I'm going to pick some up tomorrow.
 

scottm

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I disagree with the claim of ex valve damage. It runs richer than pump gas because it is not oxygenated with ethanol or ether. On a 2-stroke dirt bike it runs 2-3 jet sizes richer than straight pump gas. Plus it is leaded, which is there to lubricate and protect exhaust valves. It burns more slowly, resulting in lower peak temps and fewer nitrogen oxides. There are no downsides other than catalytic and O2 sensor damage.
 

Co-Dog

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To clarify: I'm making the assumption that we are talking about a low compression engine with the timing set to run on pump gas and no computer. Specifically the Camaro mentioned at the beginning of this thread. I honestly don't know how well engine management can deal with huge octane changes.

As octane goes up, the timing must be advanced due to the fuel burning more slowly. You don't want fuel that is still burning to be forced out the exhaust. It will run fine without advancing the timing, and that is where the problems occur. Drive 80 mph for 2 hours, get out and check out your new "ground effects". That's actually your headers glowing red. That equates to ex valve damage.

Scottm, keep in mind that a 2 stroke is a totally different animal, than a Camaro.
 

Goatpoker

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I've been down this path a few times so I'll give you what I know. I'm a Chemical Engineer and this topic came up during a visit with the Unocal Racing Fuels folks a few years back.

Key points:
-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
-Shelf life is better than pump.
-Cheaper because you are not paying Road Taxes. Legally it's like running red dye... no no on the street.
-Lower Specific gravity than pump (density) means you actually run leaner with the same jetting.
-Important one here! Lower flame speed than race gas. 100LL is designed for 3500RPM operation. If you run consistently higher than that you will be spitting unburnt fuel out the pipe. Most pre-run or play cars don't spend too much time over 3500RPM
 

Co-Dog

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I knew it had a higher density and burned slower, but the RPM factor is very interesting.
 

richard cretsinger

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we use av gas as a cleaner- degreaser in our shop. it is alot less than carb cleaner. i do know that it does not have the same lubrication ingredients that regular fuel has, there for running it with a mix like 2 stroke or 50/50 it will not harm your engine because you are adding the lubrication that your engine needs.
 

Wild bill

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I use 100LL for testing and break in. All I do is add Lucas upper cyl. lube to the fuel. Works well and never had a problem. I would NOT use it for race conditions. It causes your engine to run 20f hotter at WOT. At WOT with vp c12, I could easily keep the BBF under 200f. With 100ll 220+f. I guess this is caused by a lean condition at WOT.
 

VeryFast

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Real info on Race Gas/Av Gas...

My experience comes from 7 years as the western states representative for 76 Race Fuel, Unocals 40 hours Advanced Products course, Working personally with Tim Wusz (senior performance products Rep for Unocal, Tim was responsible for Unocals race fuel development for 30+ years). I have also met and discussed fuels/motors with just about every engine builder in every facet of racing in the western United States. I also conducted Educational Seminars at the Fred L. Hartley Institute in Brea in which we would invite Engine Builders for a tour of Unocals testing facilities and do live octane tests on any gasoline they would choose to bring to the seminar. Included in the training we would demonstrate live tests how Distillation curve, Reid Vapor Pressure, Specific Gravity, Octane Rating, F;ashpoint, etc are conducted and the importance of these numbers. Some of you will remember me from contingency with my 76 Racing Gasoline hospitality trailer in the 1990's.

Through the 50's, 60's, 70's and 80's Av gas was the base product used for most racing "gasoline". VP, f&L, Turbo Blue, and Trick all used AV gas as the base product. They would buy a tanker (8000 gallons of Av Gas) than add other hydrocarbons/TetraEthylLead (TEL) to the base, drive around the block stopping and accelerating the truck/trailer until they felt the product was mixed well. Obviously this was not science, but it worked for most racers only because most racers use a higher rated octane than they actually need.

In the mid to late 1990's VP graduated to buying there own base product and do there blending of products in a much better fashion. Turbo Blue and Trick have since been bought Sunoco and are blended by Sonoco. Trick was purchased by Phillips 66 and has continued to be blended by Phillips 66.

The only two companies I am aware of who "cracked" there own base product is Sunoco and 76. And as we all know, 76 race fuel is no longer available, leaving only one true manufacturer of Racing Gasoline....Sunoco.

AV Gas has a MOR (motor octane rating) of 96, R+M/2 rating of 100, and ROM (Research Octane Rating) of 106.

AV Gas is lighter than racing gasoline thus more fuel/larger jetting is required. Jetted correctly you should not experience a lean burn at WOT.

I would not use AV Gas as a cleaner. The amount of TEL (2 grams/gallon) and other hydrocarbons makes it extremely carcinogenic. Same goes for all other racing gasolines.

Shelf life is NOT better. The reason pump gas won't last as long is because street gas has extremely lightend hydrocarbons to help your car start and idle. Racing Gasoline does not have these light end hydrocarbons needed for idle and starting, hence the reason race motors start and idle poorly.

Av Gas is NOT designed for low RPM motors. AV Gas is designed to not detonate/preignite causing detination. This would be the same design as race fuel. If you compare the "distillation curve" of AV Gas to Race Gas, you will find they are almost identical. The "distillation curve" controls the speed of burn across the combustion chamber.

You will only "spit" gas out the exhaust pipes if you run to rich or include a supercharger/turbocharger on your engine and "overdrive" the blower. Example would be the bitchin flames you see at the starting line of a drag race on normally aspirated engines and the long flames you see on all "blown" engines.

The LEAD (TEL) added to AV Gas is to increase the octane rating only. All heads these days have harden valve seats. There is no need for lubrication of the valve seats. All engines have come with harden seats since the late 60's.

AV Gas is not formulated for High Altitude. and will have very little, if not any performance differences vs racing gasoline. On the other hand, commercial grade fuels (87, 89, 92) will definitely enhance your performance due to the commercial fuel being oxygenated. The Oxygen enhancers added to commercial fuel is only for California Smog laws.

Advancing timing on your motor will definitely help with AV Gas and Race Gas due to its slow burn characteristics. On the other hand, be careful if your running commercial grade gasoline, more timing can cause detonation/preignition quit quickly.

AV Gas does not go BAD faster. It is extremely consistent. The MOR is only 96, whereas Sunoco Purple or VP C12 is 104. A rating of 96 is good for up to 10:1 on Steel heads and 12:1 on Aluminum heads with water cooling. Air cooled motors run much hotter.

Buying a higher octane for a $20-50K motor is the cheapest insurance available.

Remember this...OCTANE is a measure of a fuels ability to resist detonation/preignition. The higher the Octane number, the slower the fuel burns. Technically speaking 87 Octane fuel will develop more power than 118 Octane fuel. With this said, you should see gains in throttle response and HP by mixing commercial fuel and AV Gas/Race Gas. You now have some light end Hydrocarbons for throttle response and heavy hydrocarbons/TEL for detonation resistance.

Bottom line... use the most consistent fuel you can find and create horsepower by moving as much air as possible though the combustion chamber.

I have no reason to be bias here as I have moved on to much greener pastures. See you on the race course.

Good Luck,
Steve Poole
 

Gonzo 5/1600

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Real info on Race Gas/Av Gas...

Good background info. But could you please elaborate on these statments:

Av Gas is NOT designed for low RPM motors.
The types of aircraft that use 100LL typically run low rpms in the scheme of motors,
example- the one I got my liscence in redlined at about 2700 rpm

AV Gas is not formulated for High Altitude.
Since av gas intended for aircraft use my understanding was that it is formulated for a more ideal mixture at altitude.

Thanks!
 

scottm

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Thanks veryfast! That is an excellent post, and it confirms what I have been saying. This is what I have learned about pump and avgas:

1. It is less volatile because it has no ether or other oxygenating additives (used year round in Phx for emissions control) and it has less of the very light fuel compounds that are used, as VF said, to aid cold starting. This is why avgas lasts longer and is more consistent.

2. The light compounds and ether in phx pump gas causes it to boil at AZ road temps - The fuel in my rv gas tank literally boils after driving for 2 hours in az summer temps. I have to cool it down with a garden hose to make it stop. I guess thats one way to get rid of the volatiles! Light pump gas would probably also boil at the low pressure of high altitude. So if avgas is formulated for altitude, it is probably reflected in its low volatility.

2. Its density may be less than race gas, but avgas does in fact run richer than Phx area pump gas. I can prove it on a dirt bike, and I can prove it again when my race truck is running in 2 weeks (dyno tune at Chucks Speed Center - I will post dyno, egt, and ex gas analyzer results).

3. Most of the misinformation about avgas was spred years ago by race gas sellers - Its ironic they were all using avgas for a base! I started drag racing in 1980 and a lot of friends had 12+:1 hot rods and they were all looking for fuel solutions. The battle to stop everyone from running avgas was fierce.

About race engines, the reason they idle poorly is mostly because of long duration cams, 260+ duration at .050" lift and 80+ degrees overlap, resulting in low manifold vacuum at low rpm. Real race engines also often run magneto or crank trigger ignitions, which make the engines hard to start because they are locked at full advance. They have no vacuum or centrifugal advance mechanisms, so they have to start at full advance!
 
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partybarge_pilot

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Thanks for all the great info!


The LEAD (TEL) added to AV Gas is to increase the octane rating only. All heads these days have harden valve seats. There is no need for lubrication of the valve seats. All engines have come with harden seats since the late 60's.

While this is true, I have noticed that the extra lead will make the rings on 2 stroke motors last much longer. Also, newer high revving 4 stroke MX bikes get better valve life as it's the valves that wear, not the seats.


With this said, you should see gains in throttle response and HP by mixing commercial fuel and AV Gas/Race Gas.

Nice to know I've been doing it right all these years.
 

VeryFast

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In Phoenix and other "boiling" spots over 100F, you should take special care of your AV Gas/Race Gas. The light end Hydrcarbons of commercial fuel start at approximately -40F. AV Gas/Race Gas starta at around 100F. So even performance gasoline looses its ideal performance. You must store your fuel in an enclosed room, not a trailer. Garages with attics or roof vents are the best. I have known drag racers who actually store there fuel in there house and in there motorhome on the trip to races. Also, keep the drums (5, 16, 30, 54 gallon) off the cement floor, preferably on a couple pieces of 2x4's. This keeps less condensation of water entering the drum. You can even go as far as turning your drum upside down so the Bungs are sealed not only by the gasket, but also by the actual fuel preventing air from entering the drum. Drums breath on a daily basis as the temp rises and falls. As they breath, air enters the drum with a minute amount of moisture. No Bueno. Always sweep the underside of the top of the drum with your finger looking for rust every time you open your drum.

High Altitude .... The reason AV Gas has a narrow distillation curve (100F to 210F avg vs -40F to 360F commercial fuel) is to rid the possibility of vapor lock in the fuel lines. AV Gas is less dense than other fuels because of the hydrocarbons used. AV Gas has no real need for throttle response, acceleration, etc. And you actually need less Octane as you climb in altitude, hence 85 octane commercial gas in some mountainous areas.

Most race fuels equally don't worry about acceleration. Thottle response/acceleration is developed through removing rotating mass within the engine (ie. light fly wheel, balancing, short skirt pistons, etc). You guys in class 9 need to really pay attention to rotating mass. Nobody would ever believe it, but my class 9 which my brother still races would do an honest 90 mph.

Yes, 2 strokes are a much different animal. They run hotter and have an incomplete burn quality. Those of you who have the thinking "more oil is better" mentality, be careful. If your engine requires a 32:1 ratio and you add a richer mixture of oil, your actually making the engine run hotter due to the fact that oil takes more heat to burn than Gasoline. Remember, Gasoline does also "cool" the combustion chamber prior to ignition. You get less cooling when you add more oil. Also reason the newer lighter 2 stroke oils are better than the old petroleum base oils.
 
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