FNQ wrote:
Basically in both the scenarios you provide the engine compartment stats will be pretty similar. ie the 180-190 degree F internal temp , but engines do love cool air and it can be felt a little. ( i had an intercooled turbo disco that used to run a touch less revs at 100km on a cold dense air night, and fuel consumption was tinily better. ..
If you drove 2000 metres up the mountain things change, but mostly the mini likes running a tad richer than stoich(14.7) anyway
You wouldn't have been using less revs at 100km/hr, unless you had something to change your gear ratio
Altitude will make a difference, but not so much in Australia, sice we don't have high altittudes. I've heard 2% per 1500 ft before, but don't quote me on that. Temperature will make a difference too, but I don't know how much.
The stoichiometric air-fuel ratio is about 14.7:1, but it's very rare for any engine to run at that. It's usually a bit richer, because the mixture is never perfectly mixed, and there is little time for combustion. A modern EFI car will run at higher air-fuel ratios on the highway, because it's better for fuel economy. But around town they will still run a little rich, just like a carburetted car - when you put your fut down, you want it to go.
