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Just been looking at the specifications for Tesco's 'Momentum' petrol. If I'm reading this correctly then it looks to me like it's only just over half petrol, with the rest made up of mixture of alcohols and other oxgenates. Not bad, but I thought with alcohol based fuels you normally needed completely different needle profile (or jet for the Weber crowd).

Link to spec : http://www.tesco.com/Momentum99/product ... -specs.asp

Sales Specification Units
Olefins 18.0% max (v/v)
Aromatics 35.0% max (v/v)
Benzene content 1.0% max (v/v)
Methanol 3.0% max (v/v)
Ethanol 5.0% max (v/v)
Iso-propyl alcohol 10.0% max (v/v)
Iso-butyl alcohol 10.0% max (v/v)
Tert-butyl alcohol 7.0% max (v/v)
Ethers (5 or more C atoms) 15.0% max (v/v)
Other Oxygenates 10.0% max (v/v)

The Olefins & Aromatics are typically what you would find in your 'classic' petrol, along with typically balance of other hydrocarbons to make up to 100%.

Does anyone on the forum have direct experience on any retuning needed when changing to this type of fuel?

AIUI "petrol" is just a label - not an actual chemical compound or mixture of such. In Oz, petrol is mainly toluene.

So, it would be interesting to know what the "half" comprising "petrol" really is.

Alcohol is a good fuel. High octane rating means lot of compression/power (read super/turbo charging) is possible but lower energy density means you need more for every HP produced...And there's the "small" matter of fuel system material compatibility...

Good luck, Cheers, Ian

[quote="carbon"]Just been looking at the specifications for Tesco's 'Momentum' petrol. If I'm reading this correctly then it looks to me like it's only just over half petrol, with the rest made up of mixture of alcohols and other oxgenates. quote]

Its interesting that the VSCC are really worried about the ethanol content, ever increasing in pump "petrol" they say this causes damage to various parts of the fuel system in their 1920/30's cars, might this also be a problem for our Mk 1's?

regards

Steady Eddie