Is Higher Octane Fuel Better?

kerry

kerry

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Our 96 year old eminent professional Vincent Guru repairer & Rider (RC) has used avgas for the past 20 years with NO PROBLEMS
I bought his Rapide just over 2 years ago, it ran superbly on it, once I changed to Esso E5 it still ran OK but never as good, Avgas also lasts years unlike anything with Ethelene which has a very short shelf life further shortened by vibration particularly in smaller amounts
Small aircraft engines I am told do run very similar to Vincent engines
 
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PaulCraven

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I’m sure classic vehicle engines run better on Avgas and a user is unlikely to be pulled over to have a fuel test!
Avgas stays fresher longer, it stays in some aircraft fuel tanks for months/years at a time without going off. My aircraft’s engine peaked at 2750rpm, cruised at 2500rpm, probably close to a Vincent’s touring speed? The lead content is quite high compared to that of leaded Mogas and plug fouling happened occasionally, but aircraft engines have twin plug heads and so not a serious safety issue.
The last Avgas price I saw was about £1.80 litre in N.Yorks.
 
vibrac

vibrac

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When I went to the local small airfield for a VMCC visit the man in charge of the microlights and small aircraft said that only one of his aircraft ran on av gas they found that Esso supreeme was better suited to their engines I wonder what they will do now?
Roll on the e-fuels zero CO2 the EU have seen the light what about uk .gov?
 
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oexing

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Most of ultralight aircraft with Rotax flat-fours run on mogas / super 95 or 98 . When you run these on avgas oil changes at shorter intervals are mandatory by Rotax due to lead content degrading the oil it seems. Same with typical avgas Lycoming or Continental aero engines when oil changes are made at 35 - 50 hours use. So I´d rather go for Ultimate 100 or V-Power 100 , still lower price than avgas . Yes, degrading by storage might be some factor. But there are fuel stabilizers available like in chain saws, lawn mowers and all for winter storage, unless you prefer emptying the tank - or fill up to the top. I never had any problems in spring so far but a tank sealer can be great, for other problems as well.
Aero engines running cooler - not really: Problem with typical American stuff is the very big bore of 5 " and detonation in max power settings like in climb for a quarter of an hour or more. You have to watch cylinder head temperatures not exceeding 200 C or 400 F much as aluminium will soften and cracked heads are well-known in turbo types within 800-1000 hours use only ! So just for max power you need all the octanes from avgas , but most of time at 75 % power mogas would do better.

Vic
 
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Bazlerker

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An octane rating higher than that which a motor requires is wasted. There is no tangible benefit from buying premium fuel when the engine in question is designed to run on regular.
 
kerry

kerry

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The reason we use the higher octane fuels here is to avoid Ethelene as best we can, our E5 Esso has up until now been free of it so better for our bikes, yes we are wasting octane's but prefer that to Ethelene
 
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Bazlerker

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kerry said:
The reason we use the higher octane fuels here is to avoid Ethelene as best we can, our E5 Esso has up until now been free of it so better for our bikes, yes we are wasting octane's but prefer that to Ethelene
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Here in Manitoba all gas has 10%-15% ethanol by volume. I simply add fuel stabilizer to the tank of all of our vehicles, top the tanks for winter storage and have never had a problem. My Rapide was just started on the 3rd kick after 9 months and settled down to a nice idle.

 
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