Originally Posted by Max...
Ahhh I see - what's GDI?
I think (and I might be shot down in flames) that Mitsubishi were the first to use the system they termed "Gasoline Direct Injection" basically injecting the fuel directly into the cylinder in a similar fashion to a diesel engine. The principal being that the 18:1 air/fuel mass ratio on idle could be pushed without causing pre-ignition. (in their case pushed to 44:1) if there was no fuel in the cylinder to pre-ignite. (injection was on or after TDC advancing with revs and load) The theory was good and it produced very low emissions on idle and good economy.....unfortunately, only if the vehicle was very lightly driven. Once it's "given a bit of stick" the economy goes out the window.
Apply the same principal on a two-stroke and the fuel isn't introduced until after the exhaust port has been covered so their inherent inefficiency caused by half the fuel charge going out the exhaust is resolved. But the hardware is not cheep and it's management system is going to require power eg 12v battery.
Justifiable on an engine costing thousands but not on one costing hundreds.