FUEL QUESTION

[Bettythemoggie]

Hi everyone,

I have a 1955 850 cc Morris 1000. It has a standard head on the engine. Each time I fill up with fuel, I add the additive. Can I use 95 Octane or, does it have to be 99 Octane fuel?

Thank you for your help
Alison

[philthehill]

Use the 95 octane fuel with additive and occasionally use the 99 octane.

[Bettythemoggie]

Thanks a lot. 95 is definitely more accessible where I live than the 99.

[Blaketon]

So long as you use the additive, that will help. It's not just the issue of lead now; you have to consider ethanol. Of my cars (All have lead free heads), only the Midget has a high enough compression ratio, to justify high octane fuel. However, it has been the case that super unleaded was less likely to contain any or at least as much ethanol. However I have been advised to use something like Millers VSP anyway these days, if only to guard against the effects of ethanol in petrol.

I can get super unleaded at the local filling station and in any case, I don't use much fuel; I could almost get away with buying a drum of Sunoco fuel and using that.

[JOWETTJAVELIN]

Ethanol will not cause any problems in a regularly used car. Any standard Minor will run on 95 RON petrol. Only cars fitted with a 1275cc engine, like Blaketon's Midget, require the higher octane petrol if you want to get the best out of them.

[irmscher]

Avgas

[Blaketon]

Avgas is ideal and was used in speed events (In non road cars at least), as it is very stable and not prone to vapour lock. Because you can buy it from pumps, at airfields, it was deemed to be "Pump" fuel. We don't know what is going to happen, in the future, as regards fuel but I think avgas could be a way out. I feel sure there will always be a demand, for avgas, from the aviation sector and combining the demand, from classic cars, with that of aviation, may provide viability. I have made this point to FBHVC. It is hardly going to create serious lead pollution. Of course it wouldn't help post cat cars but I'm not altogether sure that many of the more modern cars are going to survive to become historic (However a solution would need to be sought). I can't see anything from today lending itself to long term and DIY ownership / restoration.

My Traveller has a 1275 Midget engine and that would run on 95 octane and gave 77bhp on it but I stopped using that because of fears over too much ethanol.

My Midget is one with the Triumph engine but it's putting out 110 bhp, so yes it needs higher octane. In fact, it's a tad under 110 though it showed 111 bhp but that was only on a setting for Shell super unleaded, which at the time was the best available. I sacrificed a few bhp, for slightly less advance, in case I had to use something else.

[Monty-4]

I expect most Minors would happily run on lower than 95 octane petrol. They are hardly high compression motors unless modified.

[irmscher]

Lovely engine bay