I realize that this is probably the antithesis of what most people on the forum are looking for but to me it is important anyway. After a long search I finally found a really clean 03 GMC quadrasteer 4X4. Love the truck hate the fuel economy. On the highway it is quite acceptable, in the city however I might as well be driving a carbureted 454 dually. I do not know which engine it has in it but it needs help. Has anyone built one of these for fuel economy? the last time I put together an engine strictly for economy it was the truck block with the 3.75 bore and 3.25 stroke (307?). It had an A series carter afb and points in the distributor. Point being that it was in the dark ages shortly after the knights quit slaying dragons. While I understand the working theory behind all the electronics it adds a dimension I have no experience dealing with. It is time consuming and expensive to just throw parts at something so I am looking for some experience in the area. The object of the last build was to trap as much cylinder pressure as possible between idle and 4000 rpm. Ergo a really short camshaft small valves and ports to keep velocity up. Intake ports smoothed and polished to reduce turbulence and formation of droplets. A compression ratio in the 9's so premium fuel was not necessary. The smaller bore and longer stroke for a more complete burn in the cylinder. cast iron exhaust manifolds, single exhaust and back flow muffler to keep exhaust pressure up keeping the cylinders from completely purging. In a 64 nova it delivered 20 in town, 29 on the road and 19 towing a boat. In theory the mechanics should be similar for an engine with electronic timing and fuel control but as any engine builder knows theory alone is never the complete answer. Sorry for being so wordy but I was trying to answer any questions in advance.