Chuck84TA

Racing fuel (100+ octane) goes for $7.00 a gallon

100LL Avgas goes for $3.85 a gallon at a local airport...

I've got a E4ME carb, no catalytic converter, is it a good option to use 100LL Avgas?

Chuck

Chuck84TA

And yes, I've got a 9.7/1 compression 355

UNCLE TOM

iTrader: (1)

I really could not say for sure . I do know that the small airport I worked at many years ago , we did a booming sale on 100LL Avgas every Fri. & Sat. afternoon . just to the east of the airport was a circle dirt track racetrack . the racers loved the stuff . I do know that on Acft. sparkplug's the plugs loaded up faster than on leaded fuel . yes I remember & used leaded fuel (DAMN I'm OLD) . good luck ...

86LG4Bird

iTrader: (1)

I can say for sure. 100LL (low lead, yeah right!) will ruin your O2 sensor very quickly. Every bit as quickly as leaded racing fuel.
Other than that, yeah it's a good deal.

aliceempire

iTrader: (14)

I work with avgas all the time. Don't use it with a o2 sensor or converter, it will affect them and cause them expected problems. Performance wise I can't give you a whole lot of feedback. I haven't had any direct experience with a performance engine running it. Though my '77 400 runs great on it, but it likes 87 octane too. Avgas smells great burning though.....like lowing flying aircraft. Actually I'm surprised you can buy it if you don't have an aircraft. Tax issues and whatnot. Also surprised the price is so low, it was close to $8 at MKE here.

Chuck84TA

Yep it's $3.85 at Galt airport and its self serve with a card swipe too...really easy..

I'll probably use it when I switch to my non computer qjet so I can deep six my o2 sensor

igotta355z28

iTrader: (1)

Why are you needing such high octane fuel? 93 should be fine for your application.

86LG4Bird

iTrader: (1)

Good point! I didn't even see Post #2 above!
There is ZERO performance gain with Avgas over 93 pump in your situation. and there IS a chance you'll lose some.

aliceempire

iTrader: (14)

What would cause the power loss? I'm asking out of curiosity and haven't heard such a thing. My 400 with 8 to none compression isn't affected in the least, just smells different.

igotta355z28

iTrader: (1)

higher octane fuel is more resistant to combustion.... meaning you can run more compression and timing to make more power with less of a chance of pre ignition... if you don't have high compression you don't need the extra octane. you are just wasting money and making it harder for your engine to burn the fuel. the 11:1 ls motor I'm swapping into my car should run off 93 just fine as well. Id stick to 91 or 93 on your car.

86LG4Bird

iTrader: (1)

Of course you'll never feel it.
Because of the slightly slower burn rate of the higher octane leaded fuel, you have to run slightly more ignition timing to achieve peak combustion pressure at the correct point on the piston downstroke. The more ignition lead, the more negative work is being done on the piston as it's still rising on the compression stroke. Like I said, you'll never feel it, but on the dyno with back to back runs, setting timing to optimize each fuel, you'd likely see a couple hp favoring the 93 octane pump fuel in a low compression motor like yours.

aliceempire

iTrader: (14)

Maybe that's where I was misinformed. I was under the impression the the higher octane didn't burn at different rates, just resisted detonation more. Make complete sense though. Good thing I don't pay for the stuff.

jshaf00

100LL carries 4 times the amount of lead than regular leaded car gas had, also it is a wonderful cleaner so whatever crud is in your fuel system will end up down line at the fuel filter or carb. it is an aromatic fuel and smells great. had a bunch of excess 100LL we drained from our '41 Aeronca chief and put it in our old 65 olds 98 with the 425 super rocket ultra high compression engine, the old beast loved it smoothest I had ever seen it run, consequently anywhere fuel seeps it will leave a nice blue stain

Galaxie500XL

iTrader: (1)

That blue stain is there to show that you've used fuel that hasn't been taxed for use in an automobile...that's why it's dyed.

aliceempire

iTrader: (14)

Coming from the airline fueling industry, the blue is for both taxing purposes and sourcing fuel leaks.

86LG4Bird

iTrader: (1)

Dayyum, it's a small world
I'm Director of Engineering at the old Aeronca company in Middletown, OH. Now owned by Magellan Aerospace. We haven't produced small planes since about 1950, but still design and produce aviation and space components.
Bring that thing up to the bi-annual National Aeronca Association fly-in here at the airport! Happening this June


Also a private pilot, which is why this thread caught my eye. Unfortunately I don't have an Aeronca

petrolhead

Remember too that avgas is oxygenated. Meaning it's designed for high altitude. In most cases you will need to richen your fuel mixture to compensate. I've used it in my 13:1 motor, it doesn't make as much power with it, but does stop pinging. I never tried to re jet the carb with it. I only used it if I was going to a car show or something.

UNCLE TOM

iTrader: (1)

FWIW I soloed in a 1947 7AC in 1977 . fun acft. to fly & play with ...

jshaf00

Sadly "POPS" suffered a stroke and loss to his eyesight and we sold the chief to a fellow down in Oklahoma , I will miss it, the story on it was that it was
1 of 2 built for the Aeronca flying club during WW2. the wings on it were different than other Chiefs and it would Cruise at 110 indicated on a 65Hp Continental with a full front tank and a full rear aux tank ! dad and I had tons of fun with it and he didn't want to see the old bird sit and collect dust after he lost his medical so we sold it.

jshaf00

Avgas grades are defined primarily by their octane rating. Two ratings are applied to aviation gasolines (the lean mixture rating and the rich mixture rating) which results in a multiple numbering system e.g. Avgas 100/130 (in this case the lean mixture performance rating is 100 and the rich mixture rating is 130).

In the past, there were many different grades of aviation gasoline in general use e.g. 80/87, 91/96, 100/130,108/135 and 115/145. However, with decreasing demand these have been rationalised down to one principle grade, Avgas 100/130. (To avoid confusion and to attempt to eliminate errors in handling aviation gasoline, it is common practice to designate the grade by just the lean mixture performance, i.e. Avgas 100/130 becomes Avgas 100). More recently, an additional grade was introduced to allow one fuel to be used in engines originally designed for grades with lower lead contents: this grade is called Avgas 100LL, the LL standing for 'low lead'.

All equipment and facilities handling avgas are color coded and display prominently the API markings denoting the actual grade carried. Currently the two major grades in use internationally are Avgas 100LL and Avgas 100. To ease identification the fuels are dyed; for example Avgas 100LL is colored blue, while Avgas 100 is colored green.

Avgas fuelling nozzles for overwing dispensing are painted red. To help prevent the possibility of jet fuel being supplied to a piston engine aircraft, the nozzle of an Avgas fueller is limited to a maximum diameter of (internationally) 40 mm (49 mm in U.S.A) and the aperture on an aircraft Avgas tank to a maximum of 60 mm diameter. Nozzles for Jet A-1 are larger than 60 mm and thus cannot be placed into an aircraft's Avgas tank.

AVGas Grades

Avgas is identified by two numbers. The first is the “aviation lean” octane rating and the second is the “aviation rich” rating. The aviation lean rating is much like the anti-knock index for vehicle grade gas. Aviation rich is the rating supercharged engine conditions using an extremely rich fuel mixture combined with elevated temperatures and high manifold pressure.
•100LL – This grade of aviation fuel has a lower lead percentage than 100/130. Almost all piston aviation engines use 100LL, but it will soon be phased out because of high levels of toxic lead.
•82UL – Similar to automobile gas, this aviation gasoline is used in aircraft that have an octane rating of 82 or less or an anti-knock index of 87 or less.
•Avgas 80/87 – Because of its low octane rating, it can only be used in low compression ratio engines. It contains the least amount of lead of any aviation fuel.
•Avgas 100/130 – This higher octane grade aviation gas contains a high percentage of lead, which is why 100LL was designed as a replacement.

Avgas Color Codes

Because different aircraft require different avgas grades, aviation gases are color coded with dyes to prevent fueling mishaps.
•100LL – Blue
•82UL – Purple
•Avgas 80/87 – Red
•Avgas 100/130 – Green