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Hot Rods av gas

Discussion in 'The Hokey Ass Message Board' started by blackanblue, Jun 4, 2019.

  1. Marcosmadness
    Joined: Dec 19, 2010
    Posts: 331

    from California

    Aircraft, or more correctly, aircraft engines that have a STC (supplemental type certificate) to use auto fuel are fairly common. I had a 1959 Piper Tripacer, tail # 2960Z, with a Lycoming 0320 160 hp engine and had a STC to use auto fuel. I switched back and forth between the two fuels with no problem and basically no difference in performance worth talking about. I sold the plane some years ago and I don't know if I would want to use or even be allowed to use the auto gas with ethanol. As others have mentioned, AV gas has lead, which will contaminate catalytic converters. AV gas labeled 100 LL meaning "low lead" still has enough lead to get lead deposits on the aircraft sparkplugs. AV gas, unlike modern pump gas, doesn't go bad as quickly. Race gas, last weekend at Sonoma Raceway in Sonoma California, was $9.99 a gallon for 100, 110, 112 octane.
  2. firingorder1
    Joined: Dec 15, 2006
    Posts: 2,140


    Why not use ERC or VP race gas? I run ERC 110 at 14:1 with no problems.
  3. Stueeee
    Joined: Oct 21, 2015
    Posts: 176

    from Kent, UK

    Before I put hard valve seats in my avatar car, I used to use Avgas in it, but when I used it used undiluted, the car suffered from massive fuel vaporization issues from the under hood temperature. Mixed 50/50 with the 97 Octane unleaded "premium" petrol available here, it never suffered any issues.

    High fuel temperatures aren't going to ever be a problem with straight Avgas in an aircraft at altitude in the same way as they are going to be in a car on the road in a traffic jam.
  4. mohead1
    Joined: Jan 18, 2013
    Posts: 550


    Where u gettin 97 octane, Canada? I wish we had at least 95, no real reason why we cant have it in the states, except they want the damn ethanol in it

    Sent from my SM-G900V using Tapatalk
  5. mohead1
    Joined: Jan 18, 2013
    Posts: 550


    Thats what i was talking about several posts ago....the vapor pressure is low so it will vapor lock in a heart beat

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  6. spanners
    Joined: Feb 24, 2009
    Posts: 777


    The only reason we have ethanol in Australia is because one of our previous political leaders was in bed with one of the biggest producers of the shit. Motorists avoid it like the plague if possible.
    a boner and mohead1 like this.
  7. G-son
    Joined: Dec 19, 2012
    Posts: 526

    from Sweden

    There might be a bit of confusion between different octane ratings, as there are several scales it is rated by. MON, motor octane rating with the lowest number, done with a more severe higher rpm test, RON, research octane rating, lower rpm test, this is the number we use in Europe, and PON, pump octane rating, the average of MON and RON, this is what's used in the US.

    Confuse the different numbers and your high performance engine may have a very, very bad day.

    Another thing lots of people seem to miss is that when changing fuel the carburettor jetting will need going over, and probably changing. The fuels may have similarities, but they are quite different and the exact same adjustments are unlikely to be perfect for both. Some of the stories of failures or poor performance after changing to avgas in car engines may very well come from not adjusting the carbs for the fuel.
  8. deathrowdave
    Joined: May 27, 2014
    Posts: 1,639

    from NKy

    AV or high octane is not needed with low compression engines . Many moons ago I owned 70 Torino Cobra 429 SCJ . The fuel cap was under the license plate , when you pulled the plate down to fill the tank , there was a WARNING label attached. It stated : use minimum 105 Octane or serious engine damage could result voiding all factory warranty . That car ran sweet on AV gas , I did it for years . A Buddy of mine repaired the pumps on trucks , I would back up to the fence , he would slide the hose under and fill me up until it was running out .Just gas he would have to burn off before pump removal . If you want some hot fuel Propane is 105 Octane . It’s a bit tough to carry and burn in ones Hot Rod .
  9. khead47
    Joined: Mar 29, 2010
    Posts: 1,536


    14 to one flathead ????????????????????????????
    gimpyshotrods likes this.
  10. Boryca
    Joined: Jul 18, 2011
    Posts: 597

    from Detroit

    Aircraft mechanic here - Just tune your engine for the gas. Avgas now is mostly 100LL (blue) and the only real issue is you'll get what's called coking - a white, crusty layer of gunk - on your exhaust valves and spark plugs if you don't tune your ignition and carburetion systems properly.
    kidcampbell71 and G-son like this.
  11. I used to get AV gas at a Beechcraft facility at a local airport fro my stock cars, right off the Shell truck. Just looking at the truck set up, there are filters and what I would say is a water separator on it. Not sure if they would still sell to the public now, but they would fill 2 of my 5-gallon cans with no questions. That was 100LL back in 1984, the last time I bought AV gas.
  12. RmK57
    Joined: Dec 31, 2008
    Posts: 943


    Most of our local small airports are self serve with no attendant, just pull in and fill your gas cans.
    I wouldn't recommend filling directly into your cars tank in case somebody reports you.
  13. rudestude
    Joined: Mar 23, 2016
    Posts: 2,091


    This is funny stuff....its the best thing since sliced bread, it ruined my carburetors, my car gained 5mph in the 1/8th mile, some body told me they saw a article that says it burns up your valves so I won't use it no body should its bad...yes? real back in the 80's several of my friends, some drags some dirt trackers,would go out to the little local airport the day before race day and fill up there jugs and run it , with no problems and they run good...but there's one very good point about AV fuel that nobody has hit on yet, good or bad, and I think it's right up there with its increased performance levels.....THE SMELL...just love the smell of the stuff coming out of the exhaust...Do You Dig-It ..

    Sent from my SM-T387V using The H.A.M.B. mobile app
    egads and jimgoetz like this.
  14. It does smell great, I can tell a car right away that runs it. Also a few guys run alcohol, don't think it is E85. I use an octane booster now and then, but truly mine runs good on no-lead 93 alone.
    rudestude likes this.
  15. Lost in the Fifties
    Joined: Feb 25, 2010
    Posts: 388

    Lost in the Fifties

    Yes, I have used it. I've added 3 gallons to a tank full to bump the octane to stop pinging and at the same time it stops vapor lock. And, yes, it does smell wonderful. It stops the bad smelling exhaust on carbureted engines.
  16. Most old planes have two magnetos. two carbs and two gas tanks. If you up in the sky and something goes haywire you switch tanks and mags.
  17. That Av gas is too high dollar. I know someone who had to buy a new certified engine for his 58 Cessna. Had to pay a certified Av mechanic to install it to pass the annual. Then him and someone else took that engine apart and changed the pistons so It runs on unleaded pump gas. He carries his fuel in those red plastic gas containers.
  18. Not the ones I flew, I have flown an assortment of older general aviation aircraft. The engines did have two mags, but just a single carb, and even though some of them had more than one tank, it was still a single point fuel system. Generally speaking, there was no selector for the tanks. I might also add, that having one magneto malfunction meant a loss of power.
    The most serious concern was not mechanical failure, but carb icing, which could happen in clear air.
  19. 34Larry
    Joined: Apr 25, 2011
    Posts: 782


    With all respect KJ there never had been a problem before the Av gas, and if it wasn't the AG. why were both carbs pouring? Seems unlikely both of them would go down with the same problem at the same time .
  20. 1946caddy
    Joined: Dec 18, 2013
    Posts: 1,469

    from washington

    They lean the fuel at altitude because there is less oxygen the higher you go.
  21. We cant get nuthin but corn gas here. For my small engines and tractors. I color the gas with a small amount of two cycle oil.. for my one cyl engines I pour that colored gas into a clear glass jug. add a bit of water and shake it up. Let it settle and you can see the line where the ethanol & water mix is. Im careful not to pour that into my engines. On the tractors I let the glass settlement bulb catch the watery crap. I try and save the water ethanol mix crap, and pour it on thistles and other weeds I want to kill.
  22. 1946caddy
    Joined: Dec 18, 2013
    Posts: 1,469

    from washington

    And you would be reported for buying gas?:confused: I don't believe there is a law saying you can't buy av gas.
  23. Phil P
    Joined: Jan 1, 2018
    Posts: 129

    Phil P

    There's no law against buying av gas but in most places if your driving on public roads you can only use fuel you've paid taxes on.

    Truck64 likes this.
  24. partssaloon
    Joined: Jan 28, 2009
    Posts: 360


    I've been running AvGas for years in my boat, you can buy it here at most of the gas stations. The majority of the boats on our lake are 1000+ HP. When I put 60 gals. in I add 1 pint of MMO.
    Twin Turbo 454.jpg
  25. Pete1
    Joined: Aug 23, 2004
    Posts: 1,644

    from Wa.

    Yes. Circle track engines.
  26. Racing fuel at the pump, we have 2 choices, a couple of Sunoco stations and one known as OK Petroleum. Both places are like $10 per gallon, maybe more. No idea on the $$ of AV gas. I can get a can of octane booster for around $20, I like Torco and VP. I get a better deal on it by the box on eBay or Amazon. On 10 gallons, it raises the octane by around 4 points.
  27. G-son
    Joined: Dec 19, 2012
    Posts: 526

    from Sweden

    Octane boosters are unreliable. They may work well on one batch of fuel, another batch with different composition may not get any octane increase. Tough luck if you've tuned the engine on the fuel that got a good octane increase, and then get a tank that doesn't improve, might cost you an engine.

    Octane boosters are for people who pour it in their daily driver and want a bit of placebo effect, not for people who actually need the extra octane.

    There was a substance around that could increase the octane ratio quite a bit. Unfortunately tetraethyl lead (as in leaded gas) has too many downsides, so using that isn't really an option these days.
    Truckdoctor Andy likes this.
  28. carbking
    Joined: Dec 20, 2008
    Posts: 2,500


    Lots of "old husbands tales" (old wives are too smart to believe that &^%$) about av gas for basically stock street engines. Just like higher octane "street gas", the higher octane av gas will permit higher compression (larger mechanical advantage) engines.

    But in a nutshell, if your street engine does not detonate on 87 octane (or 91 or 93) street gas, then using av gas is only going to make your car faster because it is now lighter. From the vicinity of your wallet!

    Most folks use higher octane than they need anyway.

    Last edited: Jun 5, 2019
  29. jimgoetz
    Joined: Sep 6, 2013
    Posts: 285


    Yes, yes, and yes
  30. Truckdoctor Andy
    Joined: Jan 13, 2017
    Posts: 742

    Truckdoctor Andy

    Back in 1996, I was racing an O/T Chevy Nova in brackets. It had a 10 to 1 350, my buddy and I (he had an 11.5 to 1 350) would get AV Gas at the local airport. At the time, 110 race gas at the Drags was about 3.50-4.00 bucks a gallon. We bought 100LL for about 2 bucks a gallon. The two 350s loved it. We never had problems with it. It also smelled great! Later on, when I could get it, I’d run it in my Ironhead and Shovelhead Harleys. They liked it too! I’ve heard that around here, it’s hard to come by now.

    Sent from my iPhone using The H.A.M.B. mobile app

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