On 24/08/2015 18:50, Adrian wrote:
On Mon, 24 Aug 2015 18:43:42 +0100, NY wrote:

- diesel engines draw air into the cylinder, compress it to about 30:1
compression ratio (unlike about 7:1 for petrol)

Higher than that - 10:1 isn't that unusual in a petrol. Hell, even Land
Rovers were using 8:1 in the '60s, unless they were for a country where
petrol was about the potency of a damp fart.

And these days, lower than that for a diseasel. High compression
produces NoX in the exhaust, one of the diesel nasties.

In fact Mazda are using 14:1 for both engine types!

Andy