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Can we add fancier words like Brake-Specific Fuel Consumption (BSFC)?
@Chapap: Not sure if you got your question answered, so the below is slightly generalized but you get the trend:
The 1.5L engine in your Honda makes 192hp@5,500/190 ftlb@5,000 with 10.3:1 compression/20.2 psi boost! To do so, it needs direct fuel injection and turbocharger.
Direct fuel injection allows for the high compression/significant boost - There is no gas in the cylinder until the injectors cycle, so no chance of premature combustion (detonation).If you pull off the turbocharger, the naturally aspirated version of 1.5 Honda makes 130hp@6,600/114ft-lb@4,600. So, you can see the massive difference (62hp/76ftlb or 47%/67% respectively) that adding boost contributes. But you still need direct injection to allow the 11.5:1 compression and 4 valves/cylinder to allow the 6,600 rpm power peak.
The next step back is the Duratec 1.6 which makes 99hp@6,000/107ft-lb@4,000. Still 4 valves/cylinder, but you can see the loss in power because port fuel injection isn't as precise as direct, as a result the Duratec only had 11.0:1 compression. The Honda also revs 10% higher = 10% more power. To take advantage of the higher revs, the Honda engine would need lower gears 4.56:1, not 4.10:1 and then it needs a double overdrive 6th gear to slow it down at highway speeds.
But 107ft-lb torque isn't enough for Ranger, so Ford installed the 2.3 Duratec. Which being 42% bigger makes 44% more torque (154ft-lbs) - enough for Ranger.
Going all the way back to Lima, by only having 2 valves/cylinder, reduces volumetric efficiency, reducing both peak torque and power numbers. But there is another significant difference - the Honda and Duratecs are aluminum engines - they cost more, but aluminum transfers heat better. So, you can run higher compression numbers. And the higher compression, the more torque (there are diminishing returns, and material limits).
HotRod did a test a number of years back now, where they took 2 Chevrolet engines of equal displacement: one with largest bore and short stroke, one with smallest bore and long stroke. Heads and cam were the same, mid pack ones for more engines. And the resulting torque numbers were within instrument error on the dynamometer they were using. And power is just torque * rpm/5252.
So, we could make an aluminium 4 valve/cyl. head with direction injection for the Lima, add variable cam timing and a turbo. We'd get about 270hp@5,500/310fl-lb@3,000. (Ecoboost Ranger numbers). There is still the disadvantage of the cast iron block (weight) compared to Duratec/Ecoboost/Honda.
With the fancy head/turbo and associated programming your Lima engined Ranger with a 7 speed manual pinched from @85_Ranger4x4 's Bronco would get fuel economy numbers similar to @sgtsandman's new Ranger - better than your old, but not Accord numbers. The issue is you now have a 270hp engine in place of a 100hp one. And you really need to swap the Lima for a smaller engine to get better economy.
And as noted, you need to changed from rear wheel drive to front wheel drive to increase efficiency/lose weight. Then you need to clean up the aerodynamics of the brick you are pushing down the road.
Direct injection. That is the answer