As mentioned in my other post, the more compression in an explosion is directly related to how much power the explosion gives off...this means any way you can get more compression is good.
what a turbo charger does, is it takes the exhaust your engine pushes out, and it uses that to (basically) spin a turbine, that in turn adds more pressure to the piston, making the compression on the explosion even greater aiding power.
this is the reason that you measure turbo boost by pressure, like 5 psi, 10 psi, and the harder your engine works, the higher the number gets.
For diesel engines, that are compression run, this is essential to get more power out of an engine, because it directly helps what makes the engine run at all.
Now a final word on this post about MPG's.
To debunk all myth's, the smaller your engine the more MPG's is not nessesarily true, but often helpful.
so the faster your engine is spinning (known as RPM's), the more often each piston ignites fuel...this means the more often fuel is burned. so for starters, you should try to keep your RPM's as low as you can so fuel is not burned as often. one downside of this, your engine usually does not make much power in this range of RPM's, so you will not be the next jeff gordan here.
you can keep it in a high gear in a manual, by just keeping it in the highest available gear more often, or in an automatic by using as little throttle as possible to allow your engine to shift up.
There is one other thing to keep in mind. if you remember when i mentioned carburetors, and fuel injection, you know that the harder you press the gas the more fuel goes into the engine. if you drive around with your car in top gear, and it floored, to make up for the power loss, you are not saving any fuel. You are igniting fuel less often, but you are burning alot more fuel those times you do.
the more pistons your engine has (or the bigger the engine) the less it has to work, so you dont need much throttle, so you may be using as much fuel as if you had a smaller engine, and were working it harder.
in the end, the better you carry speed so your engine doesnt have to work at all, the better your MPG's will be.
side note...the difference between gas and diesel (petrol and diesel), is that gas is meant to be ignited with a spark, and diesel is meant to be ignited with pressure of the piston pushing on it.
so specifically this means that the diesel will explode at a lower temperature, but not as easily from a spark. (dont quote me on this, because im not sure how accurate this is)
octane is measured in the resistance to burn, so if you can get more compression to a fuel before it ignites (higher octane) the better, but more expensive. i guess this means diesel is just much higher octane.
comment with suggestions with my next post!