Can I build my own ultra lean burn natural gas engine?

[Number21]

I'm looking at various options for the most fuel efficient natural gas engines I can find. My conclusion is that all of the modern and most fuel efficient engines are very expensive and use some sort of lean burn technology, which is highly computer controlled.

It is possible for me to convert a standard, old school spark ignited natural gas engine with a simple carb/mixer and low pressure gas to run on a highly lean mixture? Lets say I take a naturally aspirated engine and add a turbocharger, doubling the air intake, but do not increase the fuel rate. Would I have problems running the engine? Can this be done without a modern computer system to control everything?

The idea/hope is to use an engine that is larger than necessary with a small fixed load for longevity, while still keeping the throttle near wide open to reduce pumping losses, just like a diesel.

Can this be done by a backyard mechanic or is this just for university studies and high dollar computer controlled gensets?

[buickanddeere]

  Lean burn means just a little bit extra air/O2 than required for the ideal stoichiometric ratio. This ensures all fuel molecules have ample opportunity to find an O2 Molecule.   
A "gross" excess of air just lowers the heat to mechanical power conversion efficiency by cooling the combustion chamber.
   Gas or diesel has highest fuel efficiency occurs at full throttle and at peak torque rpms.