Hi listers,
Octane ratings are not universally agreed and there are 3 different ways to
measure octane rating - in fact 2 ways but 3 ways of describing them.
Here in England (UK) I think that we describe the octane rating different from
the USA and I don't know how they describe the rating in Australia or Canada
or elsewhere.
Performance is a bit of a misleading word because it is pretty much down to
the compresssion ratio as to what octane rating the engine requires - even
then other factors can come into play, not least mixture strength.
For comparasion I can say that my old leaded engine ran a 11:1 CR on standard
UK four star petrol which I think is 95 or 97 Octane in the UK (not as high as
it sounds). The machine shop that built my last engine argued with me about
the CR and would not go higher than 10.5:1 even though petrol is 95 unleaded
or 98 superunleaded.
The octane rating can be boosted in many different ways including adding
alcohol but note that due to the calorific value of alcohol much larger
needle/jet sizes need to be used - though I suppose with a 10% mix the
difference is not that significant. LES - tell us how you run your gasahol
please?
As for the price - petrol in the UK is about £3.50 an english gallon which
must be around $5 a gallon. When I was in the USA one of the things I loved
was going to a gas station and filling up!!!
Daniel
PS: I've just discoverd tha the yellow edition of Vizard's book has the full
detail on page 212.
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