FighterPilot
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Using Avgas In Your Vehical?

Thu Aug 30, 2007 7:30 am

What are the pros and cons of this? I know several people that do this on a regular basis mixing it with regular gasoline.

Cal  airplane 

P.S. I figured this would be the appropriate board due to the discussion of Aviation Fuel.
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N231YE
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 8:02 am

Depending on the age of your vehicle, probably not a good idea. Remember, Avgas is leaded, and all of today's vehicles say "Unleaded Fuel Only." Supposedly, the lead will mess with the vehicles' computers, but the known issue is that lead destroys catalytic converters. On the other hand, I used to fly at a flight school with ancient, Precambrian-era refueling trucks, that required leaded fuel. The way around this? Take a "collection bottle" of fuel sump samples and dump them into the tank.  smile 

On a side note, at my university, the dispatchers use an electric golf cart to tow the airplanes around. Story goes, it wasn't always that way. Students and instructors alike used to take sumped fuel samples and dump them into the fuel tank of a gas-powered golf cart. One day, a dispatcher was towing an airplane when I guess it started smoking, then caught on fire, destroying the cart. Oh, and students and instructors are strongly encourages to put samples back into the fuel tanks of the airplane, provided the fuel is "clean and blue."
 
KELPkid
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 8:12 am

Well,

If the car is older than about 1974 or so, it might work (for a while).

The pros:

-you can give the engine lots of spark advance, getting more power
-if you're into engine rebuilding, you can also safely crank the compression higher

The cons:
-lead fouling: Avgas only has about 10 times the concentration of tetraethyl lead that automotive gasoline ever had, and your spark plugs will become fouled by it.

My dad has a '64 Ford F-100 with it's original engine, and he mixes 1 part avgas to 9 parts unleaded for fuel. It keeps it running wonderfully

In any automobile newer than 1974, lead will foul the catalytic converter, and in a computer controlled car, lead will also destoy the oxygen sensor

Also, be very very careful here in the 'States: If you are caught running leaded fuel on the road, it's a huge, FEDERAL fine

EDIT: I might add to that last statement that avgas gives the exhaust a very distinct smell, even in small concentrations.

[Edited 2007-08-30 01:13:51]
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drexotica
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 8:19 am

This is an old muscle car trick - people (and their cars) loved the high octane of avgas. Keep in mind that this is all on pre-74 cars.

The other two posters are correct - the lead will destroy the catalytic converter.
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FighterPilot
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 8:37 am

Quoting KELPkid (Reply 2):
avgas gives the exhaust a very distinct smell

Yeah, defiantly familiar with that smell.

Quoting DrExotica (Reply 3):
This is an old muscle car trick - people (and their cars) loved the high octane of avgas. Keep in mind that this is all on pre-74 cars.

I know a few snowmachine racers that use just straight avgas for races.

Thanks for the information
Cal  airplane 
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Fly2HMO
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 9:28 am

A kid in my college put straight (sumped) 100LL into his Ford Maverick, the engine ran well, and it smelled even better Big grin
 
KELPkid
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 9:51 am

Quoting FLY2HMO (Reply 5):
A kid in my college put straight (sumped) 100LL into his Ford Maverick, the engine ran well, and it smelled even better

For a minute I thought you were going to tell us you pumped some of it into your "bochito" Big grin
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71Zulu
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 9:58 am

Don't think there is any law against using leaded fuel on the street since you can still buy tetraethyl lead and add it to your pump gas to make a leaded brew for older high compression engines, but the main problem is there are no road taxes built into the price of avgas so using avgas on the street would be like using off-road diesel on the street, and if caught the fines are in the $1,000 range per violation.
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KELPkid
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 10:06 am

Quoting 71Zulu (Reply 7):
Don't think there is any law against using leaded fuel on the street since you can still buy tetraethyl lead and add it to your pump gas to make a leaded brew for older high compression engines, but the main problem is there are no road taxes built into the price of avgas so using avgas on the street would be like using off-road diesel on the street, and if caught the fines are in the $1,000 range per violation.

Might want to check this site out:

http://www.epa.gov/EPA-AIR/1996/February/Day-02/pr-1326.html

 Smile
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L-188
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 11:27 am

I knew a guy who ran some purple fuel in his truck one time,

Said it burned "REALLY" smoothly.
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Analog
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 12:10 pm

Quoting KELPkid (Reply 8):
Might want to check this site out:

http://www.epa.gov/EPA-AIR/1996/Febr....html

My brief scanning of this document indicates that introducing leaded gasoline/gasoline additives "into commerce" is banned. How does this ban putting avgas into your car for personal use?

Not that I support doing such a thing; the ban is there for good reasons.
 
DeltaGuy
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 10:11 pm

EPA...what a joke.

Back in my old FBO days, we would sump the trucks every morning....somehow though, the 100LL truck would always lose about 15-20 gallons a week, and we couldn't figure out how. We never pumped 100LL as we had little non-jet traffic at this field.

Finally figgured out it was one of our GSE mechs, just coming in at night and taking out a little bit at a time, for his racecar he was building at home that ran on 100LL. Good for him, but the company didn't see it that way.

DeltaGuy
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HAWK21M
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 10:15 pm

That would be 100 octane.....wouldn't that be higher chances of Detonation & lead fouling.

regds
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airfoilsguy
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RE: Using Avgas In Your Vehical?

Thu Aug 30, 2007 11:17 pm

You could always buy racing fuel. It is street legal and has an octane of about 104. I but it in my bike and you can tell the difference. It also has a sweet smell.

Quoting L-188 (Reply 9):
I knew a guy who ran some purple fuel in his truck one time,

That sounds like Turbo Blue racing gas.
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tdscanuck
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 12:32 am

Quoting HAWK21M (Reply 12):
That would be 100 octane.....wouldn't that be higher chances of Detonation & lead fouling.

Lead fouling would be an issue, yes. But 100 octane is higher than any normal gasoline you can get at the pump so chances of detonation should go down.

Tom.
 
Ralgha
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 3:04 am

Purple avgas isn't made anymore, and for civilian use, it was only made to order. It was 115/145 octane, where as the current low-lead (blue) is 100/130, and it had more than double the lead.

[Edited 2007-08-30 20:06:25]
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SEPilot
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 3:33 am

Quoting Ralgha (Reply 15):
Purple avgas isn't made anymore, and for civilian use, it was only made to order. It was 115/145 octane, where as the current low-lead (blue) is 100/130, and it had more than double the lead.

100LL is blue; I was under the impression that 100/130 was a different animal (don't know what color) and it had twice the lead that 100LL does. 115/145 is another creature entirely; wasn't that what the piston engine airliners used as well as the military? It had MUCH more lead.
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Ralgha
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 4:37 am

100/130 is green, 100LL is actually 100/130 they just dropped the rich rating from the name for simplicity in naming I think. Like I said, 115/145 was purple, isn't made any more, and was pretty much only for military and specialized civilian use.

100/130 (green) and 100LL (blue) are basically the same except 100LL has half as much lead.

There is a new purple avgas being made, which is 82 octane and unleaded. That may be what someone saw added to a car, but I don't see what the benefit of doing so would be. The old purple avgas probably would make the car explode.  bomb 
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KELPkid
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 5:00 am

Quoting SEPilot (Reply 16):
I was under the impression that 100/130 was a different animal (don't know what color) and it had twice the lead that 100LL does.

Green  Smile And yes, indeed, the LL in 100LL means 1/2 the lead content of 100/130 Octane. BTW, when I last flew a plane down to Mexico (at CUU), 100/130 was alive and well, and I had the Cessna 210 that I borrowed for the trip fueled up with it.
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L-188
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 10:57 am

Quoting SEPilot (Reply 16):
115/145 is another creature entirely; wasn't that what the piston engine airliners used as well as the military? It had MUCH more lead.

The purple gas he ended up with was recovered from a 1950's era underground storage tank at an airport that was used as a refueling stop on the way to Japan.
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Fly2HMO
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 11:02 am

Quoting KELPkid (Reply 6):
For a minute I thought you were going to tell us you pumped some of it into your "bochito"

O great, I have another myspace stalker  scared 

 Wink

I was actually tempted to do it, the Mexican bugs have no catalytic converter, and I could just unscrew the O2 sensor off. There's another sensor in the exhaust but I'm not sure what it's for.

Anyways, if it wasn't for those 2 things, I'd do it in a heartbeat.
 
N231YE
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 11:06 am

Quoting L-188 (Reply 19):
The purple gas he ended up with was recovered from a 1950's era underground storage tank at an airport that was used as a refueling stop on the way to Japan.

But doesn't all fuel have a limited "shelf life"?

Also, if my memory serves me right, someone here once stated that 115/145 fuel was created in small batches every so often...is this true?
 
Analog
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 3:24 pm

Quoting FLY2HMO (Reply 20):

I was actually tempted to do it, the Mexican bugs have no catalytic converter, and I could just unscrew the O2 sensor off. There's another sensor in the exhaust but I'm not sure what it's for.

Two oxygen sensors, one before the catalytic converter, one after. The second one determines if the catalytic converter is working (if not, the check engine light goes on). The converter should use oxygen, thus the second sensor should see a lower concentration than the first, which is used to determine if the engine runs rich or lean.

Oxygen sensors basically give one of two signals: too rich or too lean. Nothing in between (sort of; they have very high gain). The two signals are averaged over time to get the mixture to the correct level.

A car can run fine w/o the 2nd oxygen sensor, but the first is important to the correct functioning of the engine. (I think)
 
Fly2HMO
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 3:33 pm

Quoting Analog (Reply 22):
Two oxygen sensors, one before the catalytic converter, one after. The second one determines if the catalytic converter is working (if not, the check engine light goes on). The converter should use oxygen, thus the second sensor should see a lower concentration than the first, which is used to determine if the engine runs rich or lean.

That was my theory. Though I guess in my beetle the only purpose is for leaning, as there is no cat in the exhaust.
 
DeltaGuy
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RE: Using Avgas In Your Vehical?

Fri Aug 31, 2007 11:56 pm

Quoting Analog (Reply 22):
A car can run fine w/o the 2nd oxygen sensor, but the first is important to the correct functioning of the engine. (I think)

Correct- on my Camaro SS I had the cats removed (no one in FL cares), so I had the rear 02's "simmed out", and the 1st one I obviously retained as it gives the engine an idea of the oxygen content post-ignition. The rear 02's are not necessary unless you're running that cat.

DeltaGuy
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BAE146QT
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RE: Using Avgas In Your Vehical?

Sat Sep 01, 2007 1:27 am

Quoting Airfoilsguy (Reply 13):
You could always buy racing fuel. It is street legal and has an octane of about 104. I but it in my bike and you can tell the difference. It also has a sweet smell.

Here in the UK, BP sell a 104RON racing fuel at some forecourts, believe it or not. To be fair, these forecourts tend to be in areas where;

a) There is a publicly-accessible racetrack nearby, like Santa Pod or Brands Hatch, or,
b) The local demographic includes sufficient numbers of modifiers and owners of Skylines/350Zs, etc. I have no idea how they come by this data though.

Be careful using high-octane fuel in cars that don't call for it. If your car doesn't have a knock sensor, can't advance ignition automatically, and doesn't have manually-adjustable timing, (many Ford, Honda and Rover engines) then you will not see a performance benefit. On the other hand, you may see higher mileage out of a tank and the head temps will be lower. It's pretty marginal though.

Quoting FLY2HMO (Reply 20):
There's another sensor in the exhaust but I'm not sure what it's for.

As Analog said, it's usually to fine-tune the mixture. It's becoming more common and usually on cars which are either expensive or are REALLY geared toward economy. My luxo-barge has two, but my daily runner does not and nor does my Tomcat. The luxo-barge is older than either, however.

As for putting AVGAS in any of my cars, I wouldn't dare. I am happy to run 1% kerosene through them, though. 20 points to the first person to tell me why...  Wink
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Ralgha
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RE: Using Avgas In Your Vehical?

Sat Sep 01, 2007 1:46 am

Quoting N231YE (Reply 21):
But doesn't all fuel have a limited "shelf life"?

Yes, but avgas is specifically designed to have a very long shelf life (don't know if it's that long though). One of the differences between it and mogas, which doesn't have much of a shelf life at all.
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KELPkid
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RE: Using Avgas In Your Vehical?

Sat Sep 01, 2007 6:03 am

Quoting FLY2HMO (Reply 20):
I was actually tempted to do it, the Mexican bugs have no catalytic converter, and I could just unscrew the O2 sensor off. There's another sensor in the exhaust but I'm not sure what it's for.

Anyways, if it wasn't for those 2 things, I'd do it in a heartbeat.

Didn't the Mexico City ("Mexico D.F") bugs actually have a cat? My friend who did industrial design for all of the car factories in Puebla told me that...he said it was mandated by the Mexican government to help cut down on the horrendous pollution ("contaminacion") in Mexico City.

Didn't Pemex quit selling regular (automotive) fuel with lead some years ago, too?
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Fly2HMO
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RE: Using Avgas In Your Vehical?

Sat Sep 01, 2007 7:05 am

Quoting KELPkid (Reply 27):
Didn't the Mexico City ("Mexico D.F") bugs actually have a cat? My friend who did industrial design for all of the car factories in Puebla told me that...he said it was mandated by the Mexican government to help cut down on the horrendous pollution ("contaminacion") in Mexico City.

Honestly, I'm not sure, that's actually the first time I hear that. I've heard there are some kits for making bugs more eco-friendly, but all the [bug] taxis I've seen in Mexico City have the same muffler set up as in mine. AFAIK, later bugs (like my 2002) never came out of the factory with a cat, neither did earlier models. The 2003 bugs (a.k.a. Ultima Edicion/ Final Edition) had a revised exhaust system but it was only intended to make the thing quieter. The only thing my '02 features as far as emissions control is a carbon canister and a BOSCH ECU, though the carbon canister is comlete BS because there is nothing inside that canister, it just vents from the fuel tank. I already replaced the stock one and neither the replacement nor the one it had originally had activated carbon in them. go figure...  Yeah sure

What killed the bug was the fact that it was made illegal for use as a taxi in Mexico City, mostly due to safety and emissions. Also, marketing had a lot to do with it. The image of having a bug that cost $7000 USD being displayed in a dealership next to a VW Touareg or Phaeton, which cost north of $80000 for the better equipped versions, just didn't agree with the marketing department.

That VW plant in Puebla is a sight to behold. The size of it is amazing, and I've seen lots of car factory plants. The facade of the plant is over a mile long.

Quoting KELPkid (Reply 27):
Didn't Pemex quit selling regular (automotive) fuel with lead some years ago, too?

Many years ago actually (well, for us kids Big grin ). There used to be two grades of fuel, Pemex Nova and Pemex Magna Sin (Sin=without, without lead in this case) In the early 90's the Nova brand was dropped in favor of Pemex Premium, which is unleaded and has 92 octane, Magna Sin has 87.

Anyways, back to aviation. VW bug engines have been widely used in kit planes, the air cooled boxer engine is an identical set up to aviation engines, and heck I bet my bug's engine is more reliable than the IO-360 Lycomings I fly.

Too bad I only get 44hp out of it, but hey, chicks dig bugs Big grin
 
ThirtyEcho
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RE: Using Avgas In Your Vehical?

Sat Sep 01, 2007 7:34 pm

Very many years ago, as a 17 year-old lineboy, I closed the FBO where I worked at night and realized that my car was low on gas for the drive home. Since I was parked next to the 100/130 truck, I pumped 5 gal. into my tank to be paid for the next day.

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Tod
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RE: Using Avgas In Your Vehical?

Tue Sep 04, 2007 10:41 pm

Generally speaking, running a higher octane than you need to prevent detonation will not increase performance. As stated above, the performace gains come from the increase incompression and timing that a higher octane facilitates. Another reason to run av-gas is that it is usually more consistant than auto gas and that allows tuning closer the edge of the envelope.

Tod
 
Analog
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RE: Using Avgas In Your Vehical?

Wed Sep 05, 2007 12:45 am

Quoting DeltaGuy (Reply 24):
Correct- on my Camaro SS I had the cats removed (no one in FL cares), so I had the rear 02's "simmed out", and the 1st one I obviously retained as it gives the engine an idea of the oxygen content post-ignition.

I'm sure you're are aware that this illegal, even if FL doesn't care. Any shop that works on any part of your car's exhaust system associated with the catalytic converter (like the exhaust pipe) would be required to replace the cat.

42 U.S.C. 7522(a)(3).
[it is illegal]...
for any person to remove or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under this subchapter prior to its sale and delivery to the ultimate purchaser, or for any person knowingly to remove or render inoperative any such device or element of design after such sale and delivery to the ultimate purchaser;

http://www.epa.gov/compliance/resour.../civil/caa/mobile/exhsysrepair.pdf

Quoting DeltaGuy (Reply 24):
The rear 02's are not necessary unless you're running that cat.

I don't think they're necessary then either. What they're required for is OBD-II compliance to ensure that the cat is functioning.

Quoting Tod (Reply 30):
Generally speaking, running a higher octane than you need to prevent detonation will not increase performance.

But if your car's computer changes the definition of "needed to prevent detonation" in response to higher octane gas, then you can get an increase in power.
 
prebennorholm
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RE: Using Avgas In Your Vehical?

Wed Sep 05, 2007 9:13 am

AVGAS 100LL was formulated some 25 years ago in order to replace two grades - AVGAS 80/87 and AVGAS 100/130 - by one single grade.

80/87 contained very little lead or was unleaded. 100LL contains so little lead that it could be accepted by manufacturers of 80/87-optimized engines without excessive fouling of the spark plugs, while maintaining the knock resistance of 100/130.

The "LL" suffix of 100LL actually means "low lead".

One important property of AVGAS (vs. MOGAS - ordinary gas for cars) is that it totally lacks components with very low boiling temperature. Boiling temperature drops with lower ambient pressure, and AVGAS shall not boil in aircraft tanks at high altitude, and especially not in the fuel lines from the tank or in the carburettor or injection system.

Cars on the other hand are mostly operated at ground level. MOGAS is formulated differently according to season of the year. During winter it contains large amounts of hydrocarbon components with low boiling point in order to ease starting at very low temperatures and get a smoother and less polluting ride while warming up.

Summer MOGAS and AVGAS is in this respect not very different. But AVGAS is guaranteed to be totally free of components with low boiling temperature, while you will always get a little winter MOGAS even in summer, since it is blended in the tank at the service station.

If you have an old (pre-1974) carburettor equipped car and run it year around on AVGAS 100LL, then expect a rough star at very low winter temperatures and pull the choke handle somewhat more generously than you would on MOGAS. If you have automatic choke on the carburettor, then expect trouble or at least a rough warm up ride. And in any case you will generate a lot more smoke until the engine is warm.

Some people think that a higher octane number means more power. It isn't that simple. There is no more energy in high octane fuel than in low octane fuel. But an engine, which is optimized for high octane fuel, can have a higher efficiency.

Many modern engines have a knock sensor which automatically advances ignition according to fuel octane number. But if such an engine it optimized for, say, 95 octane fuel, then you gain absolutely nothing with 100 octane fuel. Using 95 octane it will advance the ignition to the optimal timing. If it advanced even further, it would drop in power, even if it didn't knock. Only if you use fuel with lower than 95 octane number will it advance less, and drop in power and efficiency.

You will have to modify such an engine with higher compression ratio to get any gain from 100 octane fuel. And then you may still run it on 95 octane and lose that gain again.

But as stated by many contributors before: NEVER EVER use AVGAS on an engine which is equipped with catalytic converter and lambda sensor - cars which are made for unleaded fuel. It destroys both the sensor and the converter.
Always keep your number of landings equal to your number of take-offs
 
Analog
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RE: Using Avgas In Your Vehical?

Wed Sep 05, 2007 10:51 am

Quoting Prebennorholm (Reply 32):
Cars on the other hand are mostly operated at ground level.

One would certainly hope so.

All joking aside, cars typically can make it up to 14,000 ft w/o problems. No as to long term operation... ?

Quoting Prebennorholm (Reply 32):
lambda sensor

Translation for the rest of us: oxygen sensor.

Here's a neat reference on AVGAS: http://www.chevron.com/products/prod...viationfuel/9_ag_specsandtest.shtm

Quoting Prebennorholm (Reply 32):
100LL contains so little lead that it could be accepted by manufacturers of 80/87-optimized engines without excessive fouling of the spark plugs, while maintaining the knock resistance of 100/130.

"Little" basically means half of 100/130, and about the same order of magnitude as leaded [car] gasoline
 
prebennorholm
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RE: Using Avgas In Your Vehical?

Thu Sep 06, 2007 6:10 am

Quoting Analog (Reply 33):
"Little" basically means half of 100/130, and about the same order of magnitude as leaded [car] gasoline

In most European countries lead additive (tetraethyl lead - TEL) was gradually phased out of MOGAS, from typically 0.80 - 0.90 mL TEL/L when unrestricted to max 0.40 mL TEL/L and later max 0.15 mL TEL/L until it was phased out roughly 20 years ago.

AVGAS 100LL spec is typically 0.50 mL TEL/L, max 0.53.
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Analog
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RE: Using Avgas In Your Vehical?

Thu Sep 06, 2007 7:33 am

Quoting Prebennorholm (Reply 34):

In most European countries lead additive (tetraethyl lead - TEL) was gradually phased out of MOGAS, from typically 0.80 - 0.90 mL TEL/L when unrestricted to max 0.40 mL TEL/L and later max 0.15 mL TEL/L until it was phased out roughly 20 years ago.

AVGAS 100LL spec is typically 0.50 mL TEL/L, max 0.53.

So 100LL has 0.50mL/L TEL vs. 0.8 - 0.9mL/L for leaded car gasoline (I was talking about the historical meaning of "leaded gasoline")... same order of magnitude.
 
prebennorholm
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RE: Using Avgas In Your Vehical?

Thu Sep 06, 2007 9:14 am

Absolutely right, Analog. In a historic perspective AVGAS and MOGAS had very equal lead contents.

Originally AVGAS 100/130 and MOGAS were both close to 1 mL/L.

Roughly at the same time as 100LL was formulated at 0.50, MOGAS was restricted to 0.40.

Then luckily lead in MOGAS gradually got totally banned.

That was possible because cars unlike planes normally don't get 50 years old.

Most modern cars are optimized for 95 octane gas which is the highest octane rating which can be produced in a sensible, economic way from crude oil without octane boosting additives.

Unlike that, 100 octane gas has been very much a standard on planes since WWII.

Boosting 95 octane gas to 100 without lead is next to impossible. It could be done by adding a very high percentage of a chemical fluid named methyl tertiary butyl ether (MTBE), but that would have some nasty side effects, not least that the price would skyrocket.

In addition many old aircraft engines could not be certified for such a fuel because of (suspected) incompatibility with gaskets, fuel filters and other engine components. At least long duration and costly tests would be needed to re-certify such engines for such a fuel.

Anyway some especially German cars are optimized for 98 octane gas (but run beautifully on 95 octane with knock sensor at slightly reduced power). 98 octane is produced from 95 octane with a substantial amount of MTBE added, and is sold at a considerably higher price.

In my country MTBE is next to banned since it is a terrible environmental poison. Small quantities of spilled MTBE can totally spoil drinking water recovery from huge areas for hundreds of years. (Here in Denmark we have perfect drinking water all over as utility water supply, and it is all recovered from underground). Therefore the few service stations offering 98 octane fuel are under much stricter control with much more frequent pressure testing of tanks and much lower allowed maximum age of tanks, which boosts the price much more than the octane number.

At least one company in Germany even sells 100 octane MOGAS. It is produced from natural 97 octane gas made from specially favorable qualities of crude oil from certain North Sea oil wells and boosted to 100 with MTBE. That same company sells minor quantities of unboosted 97 octane MOGAS in my country at a high price.
Always keep your number of landings equal to your number of take-offs
 
Analog
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RE: Using Avgas In Your Vehical?

Thu Sep 06, 2007 11:59 pm

Quoting Prebennorholm (Reply 36):

That was possible because cars unlike planes normally don't get 50 years old.

And car engine designs are not 50 years old.  old 

Quoting Prebennorholm (Reply 36):

Anyway some especially German cars are optimized for 98 octane gas (but run beautifully on 95 octane with knock sensor at slightly reduced power). 98 octane is produced from 95 octane with a substantial amount of MTBE added, and is sold at a considerably higher price.

The difference in Germany (and the rest of Europe/the world?) is that octane numbers are specified in RON (research octane number), whereas US car gasoline octane is specified in (R + M)/2 (average of research and motor octane numbers: take a look at the yellow stickers). MONs are a bit lower than RONs (by almost 10 points). RON is about 4-5 points higher than (R+M)/2, so German 98 octane gas is similar to US 93 octane super.

100LL is 100 MON, 130 RON (octane ratings above 100 are called performance numbers), I think.

http://en.wikipedia.org/wiki/Octane_rating
 
prebennorholm
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RE: Using Avgas In Your Vehical?

Fri Sep 07, 2007 6:24 am

Thats right, Analog. It is most confusing that there are three different test methods giving three different values of octane numbers:

Aviation world wide: MON or ASTM D2700
Europe+ cars: RON (the very old Bristish standard - in fact also ASTM D2699)
America cars: R+M/2 or AKI (anti knock index) or RdON (road octane number)

Fortunately there is for most practical things a direct relationship between those three numbers:

RON = MON + 9 (give and take +/- 1 or 1.5 depending on the actual chemical composition of the gas).
R+M/2 is simply the average figure of the two other test methods - or MON + 4.5.

That means that AVGAS 100LL on a German road gas pump would be titled 109 octane.

That gives numbers to prove my previous statement, it is not practical to produce an unleaded AVGAS 100.
Always keep your number of landings equal to your number of take-offs
 
Analog
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RE: Using Avgas In Your Vehical?

Fri Sep 07, 2007 7:01 am

Quoting Prebennorholm (Reply 38):

That gives numbers to prove my previous statement, it is not practical to produce an unleaded AVGAS 100.

What's wrong with pure ethanol? Obviously the water problem, mixtures would have to be adjusted, and that it would not work with current engines (seals, etc.).
 
prebennorholm
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RE: Using Avgas In Your Vehical?

Fri Sep 07, 2007 8:40 am

Quoting Analog (Reply 39):
What's wrong with pure ethanol? Obviously the water problem, mixtures would have to be adjusted, and that it would not work with current engines (seals, etc.).

Nothing wrong with ethanol (except if we drink too much of it).

But in addition to the disadvantages you mention there are a few more serious disadvantages.

1. Pure ethanol will need preheating for start of a cold spark ignition engine. That problem could be overcome on the ground (a small bottle of butane would probably do the trick), but certification would also require re-start of a cold engine in the air. That would require some innovative re-design on existing engines.

2. Ethanol contain approximately 60% of the energy contained by gas. The same mass of ethanol in your tank will reduce range by 40%. The Air - fuel ratio for a pretty lean cruise mixture will have to drop from roughly 14 to 8.

If 100LL shall be phased out, then there is no other option than having two different fuels for some period of several decades.

As unleaded 100LL replacement an unleaded AVGAS with MON in the 85-88 range would be much favorable compared to ethanol. Such engines could easily be produced as new engines with slight changes to existing engines with modest performance reductions.

In addition old engines made for the old AVGAS 80/87 could use it right away, maybe some of them with a tiny amount of valve lubricant additive. In fact those old engines would benefit from such a fuel compared to 100LL since the spark plugs will be a lot cleaner.

Slightly modified subject: Me thinks that pretty soon many new-built aircrafts, which today use AVGAS 100LL, will be fitted with diesel engines running on Jet A(1).
Always keep your number of landings equal to your number of take-offs
 
AussieAMEgirl
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RE: Using Avgas In Your Vehical?

Fri Sep 07, 2007 10:15 am

I remember doing a major servicing on a DC3 a few years ago and we had to drain the tanks. Of course the AVGAS found its way into 44 gallon drums and taken home by the volunteer maintainers!

I ran my Mini Clubman 76 model with its rebored 1275cc engine on it but after using it for a month found that due to the higher flash point I had to remove the head to lap and reseat all my valves!!

Gave me a bit extra grunt but some work so have never used it since in a motor vehicle!
 
KELPkid
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RE: Using Avgas In Your Vehical?

Fri Sep 07, 2007 3:08 pm

Quoting Prebennorholm (Reply 40):
As unleaded 100LL replacement an unleaded AVGAS with MON in the 85-88 range would be much favorable compared to ethanol. Such engines could easily be produced as new engines with slight changes to existing engines with modest performance reductions.

In addition old engines made for the old AVGAS 80/87 could use it right away, maybe some of them with a tiny amount of valve lubricant additive. In fact those old engines would benefit from such a fuel compared to 100LL since the spark plugs will be a lot cleaner.

Well, the US has defined a new avgas spec, 82UL, which is basically tightly controlled mogas (minus the "wierd" additives that local refineries add to the mix here in the USA...). It is about to get a major push, as the upcoming Cessna 162 will be using a Continental O-200 (yes, they're putting that engine back into production  Wink ) certified for use with that particular fuel. 82UL is dyed purple (not to be mistaken with the old 115/145 avgas grade, now only available at the Reno Air Races). As I recall, the original plan was to have 82UL undyed. I wonder what happened there...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
Tod
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RE: Using Avgas In Your Vehical?

Fri Sep 07, 2007 10:17 pm

Quoting KELPkid (Reply 42):
As I recall, the original plan was to have 82UL undyed. I wonder what happened there...

Undyed gas would hard for the tax man to detect when used on the road.

Tod
 
ZBBYLW
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Joined: Wed Nov 01, 2006 8:17 am

RE: Using Avgas In Your Vehical?

Sat Sep 08, 2007 2:19 pm

Quoting N231YE (Reply 21):
Also, if my memory serves me right, someone here once stated that 115/145 fuel was created in small batches every so often...is this true?

I believe it is done once a year for the Reno Air Races.

Quoting BAe146QT (Reply 25):
As for putting AVGAS in any of my cars, I wouldn't dare. I am happy to run 1% kerosene through them, though. 20 points to the first person to tell me why...

Ummm do you have a diesel car? My friend uses Jet-A in his VW Rabbit.
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BAE146QT
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RE: Using Avgas In Your Vehical?

Sun Sep 09, 2007 6:08 am

Quoting ZBBYLW (Reply 44):
Ummm do you have a diesel car? My friend uses Jet-A in his VW Rabbit.

A good guess, but no. All three of mine are petrol/gasoline.

What I was referring to was running a small shot of kero through with a tank of fuel to clean the injectors.

Most "engine cleaners" on the market here are nothing more than kerosene and detergent. We have a product here in the UK called "Redex" which is pretty much that. I use it every 6 months with a tank of super. My 10-year-old Tourer (which is modified all to hell) and 9-year old Tomcat are cherry, and the injectors are as clean as the day they were installed.

I doubt that's the quality of British fuel. I've seen much younger, untreated cars die from being coked up.
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