High and Low Compression Engines

[Bodge]

Hi

I'm trying to understand the main differences between high and low compression engines used on Minis and their derivatives. Can anyone help?

I've found out that most low compression engines had a compression ratio of 8.3:1, high compression engines a compression ratio of 9.1:1 and that some Cooper S models had an even higher compression ratio.

However what dictated whether an individual vehicle was given a particular engine type? I wonder whether it was something to do with the quality of fuel available at the destination country or whether dealers were given the choice when ordering vehicles.

Does anyone also know what were the internal differences? Did the two engine types come with different pistons and did it involve a different distributor? I also wonder whether it make any difference to the power output? All good stuff. Roger

[ivor badger]

Low compression engines were for areas with low octane fuel.

Rich needle recommendation s were for areas with a cold climate (Scandinavia) and lean needles were for altitude (Switzerland, Mexico city).

Volkswagen beetles in Mexico city were fitted with high compression engines and went much quicker than std spec vehicles at sea level

[foxy52]

ivor b,.. thats a fascinating piece of info ,its amazing what u learn/glean from others..tks.