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  • 29-06-2018 5:33pm
    Registered Users Posts: 4,954 ✭✭✭

    Ok.. so I've a strange one.

    I've a classic car, it has no catalytic converter, and was designed to run on premium leaded petrol.

    IF I was to get my hands on some AVGAS ie, petrol for aeroplanes, what would be the downside ?

    The fuel will be bought for use within the eu, so the full duty will be paid.

    I currently use fuel preservatives for when its parked up, but as I only use a tank or two per year, would I be better off getting 100L of leaded AVGAS, and just using that. ?


  • Registered Users Posts: 12,237 ✭✭✭✭Cee-Jay-Cee

    I wouldn’t risk it, it’ll damage valves and seals and coats parts in lead deposits even if only used the odd time.

    You’d be better off buying lead additive to add to regular petrol.

  • Registered Users Posts: 4,358 ✭✭✭kev1.3s

    I used to run avgas in an old ford falcon when i worked on the great central road in Australia, we were told that it givss a little more omph but eventually takes its toll on youre engine which wouldn't matter too much in the aboriginal communitys because the cars were pretty disposable.

  • Registered Users Posts: 4,954 ✭✭✭mikeecho

    If it'll cause damage, I'll give it a miss

  • Registered Users Posts: 2,272 ✭✭✭w124man

    Use it raw and don't spare the horses! Then show us pics of the engine bits ...

  • Registered Users Posts: 37,750 ✭✭✭✭Dan Jaman

    As a penniless student, I ran an old Minivan on avgas for a year or so. Never did it any harm, but it wasn't designed to be fussy about its fuel in the first place.
    It certainly didn't give it any extra power, as the relatively low CR saw to that, but I'd say it ran a little smoother.
    Вашему собственному бычьему дерьму нельзя верить - V Putin

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  • Registered Users Posts: 4,954 ✭✭✭mikeecho

    Can someone explain how it would cause damage.

    My understanding is that AVGAS is just 105ron with 0%ethanol.

    The classic car doesn't have a catalytic converter, and was originally designed to run on leaded petrol.

    At this stage I'm only interested in learning about it.

  • Registered Users Posts: 37,750 ✭✭✭✭Dan Jaman

    I very much doubt it will cause damage to an engine from the days of leaded petrol, especially if that engine was designed for leaded petrol of RON 99 or more. That's pretty much what the old 5 Star rating was about. <nostalgia>
    Not knowing exactly what it is, I'd guess that your engine was designed to use the lead in the petrol to lubricate valve seats and stems, so it's a win-win.
    I was using the fairly common 100LL at the time, and although it has less lead in it than was allowed, it still had plenty and kept the old Mini engine happy. If it had been a highly-tuned Janspeed lump, it would have been a lot better, of course. :)
    Scroll down to the UK section both for a current reference and to see that BP (and others) have tried bringing it back in a way. Not leaded, as such, but more of a higher RON, which helps to combat the ditchwater that most modern petrols are.

    Possible downsides of too much lead are;
    excessive lead deposits on piston rings, possibly leading to a sticky ring situation, but unlikely...
    poisoning if the neighbour's cat if it gets too cosy with the exhaust pipe

    If I had easy access now to some Avgas, I'd quite happily run some in my bikes, just for old times sake. My bike engines are all designed for unleaded, but they really wake up a bit when I put something decent in the tank.
    Вашему собственному бычьему дерьму нельзя верить - V Putin

  • Registered Users Posts: 4,954 ✭✭✭mikeecho

    It's probably not worth the trouble of getting AVGAS, given that it's sold by tbe 100L , and my tank only takes 40L.
    And that I only use two or three tanks a year at most.

    I'll stick to what I can get at the pump, and use some fuel stabilizer.

  • Registered Users Posts: 37,750 ✭✭✭✭Dan Jaman

    You could approach a small aircraft operator, for a few gallons at a time.
    Legalities - road fuel is taxed differently (and more) than other fuels, so contact the Revenuers to keep your feet clean on this. Just tell them your plans, cough up a few quid in advance duty on the likely use, and get a receipt. This is assuming you find a small aircraft operator who doesn't mind. There's really nothing illegal about the actual use of this in small amounts in specialised / classic vehicles. It would of course, be a different matter if everybody was doing it.

    Running it on 100% Avgas isn't needed anyway, I'd quite happily run a leaded generation engine on a blend of 50% unleaded 50% Avgas.

    If you really must use pump fuel - the best available, in my opinion, at Irish pumps is Texaco. Most of the rest is crap. The way my engines run tell me this.
    Вашему собственному бычьему дерьму нельзя верить - V Putin

  • Registered Users Posts: 16 falcof8l


    I am a pilot and have flown for the last 30 years in piston powered aircraft running on 100LL Avgas. LL stands for Low Lead....low lead when compared to older aviation fuels, not compared to modern auto fuel.

    The majority of legacy engines are air-cooled horizontally opposed engines manufactured by Lycoming or Continental (RR built under licence from Continental). They were designed in the 1930s/1940s to run on 80/87 Avgas. (Piston fighters used 140/145). They are very low tech, dual magnetos, dual spark plugs, carburetor, manual carb heat control, manual mixture control, straight oil. 100hp from 6 litre displacement.

    In the early 1980s 80/87 was replaced with 100LL, this resulted in lead fouling of the spark plugs, needing to be cleaned out at every 50 hr check. There were no issues with valve seats, as lead was being used as a lubricant.

    If you were to buy 100LL Avgas in Ireland, it's not far off €3 a litre.

    For modern aviation engines there is 91UL.

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  • Registered Users Posts: 135 ✭✭2.8trooper

    buying a 100l to use two or three tanks a year wouldn't be advisable avgas will go stale and loose some of its octane when not used just as normal petrol will go stale we still use avgas here in new zealand and is available at selected service stations or local airfields to buy but generally for compition use in higher cr engines,we also need to be a member of a club to be able to buy it.
    in short not worth the hassle