I know in the last 30 years turbos and superchargers have made it easier to make power, but I always hear about huge 7 or 8 liter engines made in the 70s or earlier, that will make like 200 hp at best. How is it possible to get so little out of so much displacement?
In: 37
More like 40-50 years, and a lot of this also has to do with how easy/cheap things are too manufacture. But in two words: Volumetric Efficiency. Engines are just giant air pumps. You cram more air in each cylinder per cycle, and you’ve effectively driven more air through the pump. Air moving = energy (because air has mass and thermal properties).
The higher the cylinder pressure, the more fuel & air you’ve crammed into the cylinder, the more power you make per ignition.
The biggest factor in our ability to manufacture cheap, high-pressure engines is: Metallurgy. Metals have made leaps and bounds in the past 30 years, and where once you needed expensive iron closed-deck blocks to eke out big cylinder pressure, you can now more easily do with carefully-designed, precision-machined aluminum blocks that weigh less, have better thermal properties, more homogeneous crystalline structure (stiffer), and thus can manage higher cylinder pressures (more boost).
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