Airplane/aviation fuel

Has anyone ever ran Airplane/aviation fuel in the car? There's a old timer at the track that does it and swears by it. He does run a Chevy that is about a 11:1 engine. I did some looking online and 99.9% of the things I read say not to. Just curious the affects that it would cause by running it.

Run it in several vehicles from street cars to race cars. Started using it when I had some left over from my Lycoming powered airboat. Many race gas manufactures use or used it as the base for the fuels they sell. My airport only allows me to carry fuel jugs into the pump and carry them out so I don't usually buy more then 15 gallons at a time. The pump is a just a self service credit card type pump. I even run my small engines on it before I park them for seasonal storage. Remember it is leaded fuel and will effect oxygen sensors if you are using them.

do you run the 100LL or JetA?

Leaded fuel has lead and new engines have sensors
and the will quit.. thats the big factor..if you
run O2 sensors... dont bother
(LL is low lead)

It works okay in most applications but you have to watch out for the lead. It will kill O2 sensors over time. It also changes the way you read plugs. I don't think I'd use it in a serious race engine but I know lots of guys who mix it with unleaded to give an old muscle car a little more octane.

Jet fuel (there's variants, but a very common one is known as Jet A) is really close to regular old diesel fuel. And, for that matter, kerosene. You can even run it straight in your diesel car or truck, though it doesn't lubricate as well so if you do, you'd want to add some sort of lubrication additive.

I run 100 low lead

Jet fuel isnt made for your auto style engine..
you DONT want that

First hand experience ... avgas has a different specific gravity than regular pump gas because it has to work at high altitudes. Subsequently using even a 10% mixture of avgas will necessitate a float adjustment. So that's fine and dandy as long as you always run whatever mixture you decide on. BUT, if you ever change the mixture and don't adjust your floats, the car will run like absolute CRAP. Personally I didn't see any benefit and it was a big hassle.

I've been running it for 25yrs+ great fuel lots of serious guys running it go over to yellowbullet to get some real advice.you can run it straight up to 13.1 ish then after that add some MMT to it.google it

I’ve been running it for a few years with no issues - 12:1 compression. It’s usually pretty accessible and a lot cheaper than 110 race gas (up here in the Midwest anyway). I paid $4.50/gal last fall.

We dyno’d a blown small block with it and made 725hp with no detonation.

As previously mentioned - I’d stay clear if you’re running an O2 sensor.

It's true that 100LL has lower density than most pump fuels. However that is also true of many race fuels.
Temperature plays a role in density specs but here's some published numbers to give some idea of the variations.
Specific gravities
100LL, 0.714 to .719
Pump Gas .74 typical
Sunoco GT .734
Sunoco GTX .764
Sunoco Standard .729
VP Vintage leaded .715
VP C9 .718
VP Blaze 100 .746

Race fuel info came from Sunoco Race Fuels and VP websites.
Pump Gas came from CRC E67 fuel Study (Durbin et al) and similar sources.
Av Gas from Fuel Mfc. Bulletins eg. Shell Au 100LL pdf

Distilation curve falls between typical street fuels and the race fuels I looked at. Posted a graph here:
https://www.tapatalk.com/groups/racingfu...579.html#p12657

I've used and tested 100 LL for a long time, I bought my first airplane in 1989. I've never used or tested 100LL from east of the rocky mountains so I'm not sure how 100 LL from there would test as far as specific gravity, all of the 100 LL I've tested has been right at .690, never above including when sitting during the winter in the airplane fuel cells inside the hangar
I use to buy and use 115-135 Avaition and even some 130-145 octane aviation fuel back when the airlines still used big HP piston engines in their airplanes, that stuff had a lot of lead in it
As far as the additives used in 100 LL it has a standard shelf life of up to 18 monthes Todays pump swill usually has 90 days max life exposed to air n your car tank
OP as far as using 100LL in a race car be prepared to change your jetting, spark plug heat range and ignition timing to make the motor not hurt itself on 100LL
E85 is a much better choice in my opinion for todays world of drag racing

I have used it in the past a lot.
Even dynoed engines with it .
No problems even with my O2s. But I was willing to sacrifice a sensor or two if need be.
made over 950hp with spray with no problems.
At 1162 hp I did see some specs on the plug so at that point I stepped up to VP NOS .
All and all it is a good fuel if you can still get it.
Will require a jet change though

Cab, That's very interesting. Maybe some of the other aviation guys will chime in on the density. I also looked at BP & Exxon but that was a while back and did not take notes about temperature or methods or if they were even mentioned.

Bottom line does seem to be that jetting will likely need to be adjusted for optimum performance. Probably true for most any change in fuel.

I run it Down Under when ever I get the chance, our cars seem to run better on it, 2 mph last time i changed over.

For the jet changes, is it typically take a larger or smaller jet?

Its been awhile but i think it was 2-4 larger
Of course you will need to Check your plugs for the tune up

X2...this is the way I run it in my GTX, seems to work fine, been running it this way for the last year or so..."seat of the pants" feel tells me it pulls a little harder than straight super unleaded...and the exhaust aroma is an added benefit

I ran 100LL AvGas for a long time in a 12:1 440 street/strip combo. Ran great and never hurt anything.
Know a local guy that ran it for YEARS in a 13:1 BB Chevy w/ 2 stages of nitrous. One of those guys that bought up leftover parts people were scared to run, but built an engine out of them that ran for years...too cheap to buy race fuel, so he always ran Avgas. Worked great for him.

This is one of those subjects that 99% of the people telling you not to run it have zero experience w/ it and are just repeating hearsay.

100% true Chip kinda makes me laugh at some of the stories tho....as far as tune up it should be close if your running race gas already like c12 or ?? my jetting stays the same. if its pump gas probably need to be little richer when switching to AV.the only time I need to change anything on my setup and Ill run 3/4 different types of fuel depending on my resources is when I use Q16 which is a lot richer than AV.as a matter of fact this year and from now on I will be using AV gas 95% of the time or Q16 if I
want alittle more performance its the only fuel thats ever outperformed the AV gas everything else runs the same.

I've run AvGas in my collector cars that sit through the winters, no issues at all. The cars run great on that stuff. All of the cars have modified engines with higher compression, so pump gas is borderline anyway, after sitting for a few months I couldn't hardly get the cars to run. Using AvGas there is no issue for storage, and I can drive them hard without worry.

My current mixture is 2 gal of 110 with 3 gal of 93 pump gas. Trying to get away from pump gas, but don't need straight race fuel for my engines as I'm at 10.9:1 compression.

110, That's probably 'Standard.'
https://www.sunocoracefuels.com/fuels/compare-fuels
https://www.sunocoracefuels.com/fuel/standard

Its going to be tough to calculate the change unless you measure the SG yourself. The pump gas specs will vary depending on where you live, time of year, and batch. Most of Md, the first two variables will apply. Chart from Exxonmobile reposted here:
https://www.tapatalk.com/groups/racingfu...s10.html#p16730

Its a little different than what we get up here, but both are Complex Model Refomulated Gas (RFG). For SE Penns'ia, if I understand correctly, it should meet 8.5 RVP in summer and is allowed 11.5 RVP Winter. Also that refiners need to supply Summer blend by May 1, but retailers have until June 1 to be switched over. Southern RFG may be a little different, along with the mandated summer/winter switch over dates. Winter blends are a b*tch in warm weather.

Anyway I think you just going to have to test at the track

What does specific gravity have to do with the tune/jet/heat range of spark plugs?

Can't answer the last part. Assuming the fuel is similar, I would think no effect on heat range.

re Jetting. If the density is signficantly different, the amount of fuel (mass) going through the restrictions will be different. The volume passed will be the same but the mass change changes.

I don't know if that's more important than the Stoich ratio, which also varies. If you look at the Sunoco's or Vp's specs, you can see the stoich varies as well as the specific gravities. On average, we can pretty much assume our street fuels with eth have stoic AFR rations less than 14.7 to 1.

For the guys (gals) looking for the last drop of power or consistancy an advantage of racing fuel that all the properties are published and consistant.

I look at that as the way to measure how thick the gasoline molicules (SP?)are, the higher S.G. the closer the molicules are to each other(thicker ) so I have needed to lean the fuel mixture to get the spark plugs and time slips the best I can get them, 100 L.L. aviation fuel with .690 S.G. I bought and used needed bigger jets than on race gas to get close to what I liked to see on race gas with .740 S.G.
Always jet up until the 1/4 MPH slows down, no matter what type of gas

We've used AVGAS and a Super unleaded 50/50 mix for years and on many different engines with no issues, race gas is just so expensive over here in the UK. The 100LL is about a 1/2 of the price of real race gas.
I once had to get some race gas at the track as I progressed through the rounds and ran out of my normal avgas/super mix. FWIW we didn't notice any difference in performance or any change in the AFR's just a lighter wallet