Have you ever wondered why we don’t use gunpowder to run the internal combustion engine? Neither did we. But the gearheads at Jalopnik apparently have a lot of time on their hands.
If gunpowder can get a bullet moving with great speed very quickly, why not a car?
Well, it turns out you’d need a lot of gunpowder. That’s because gunpowder, at best, has a specific energy density of 11.3 megajoules per kilogram (which was delightfully laid out in a study that tried to examine whether or not gunpowder could be used for welding).
Gasoline, on the other hand, sits at a whopping 46.4 megajoules per kilogram. That’s more than ethanol (30 MJ/kg) coal (33 MJ/kg), even jet fuel (43 MJ/kg). Gasoline packs a serious punch in a little package.
Gunpowder has a shockingly little amount of energy in it. Bullets can move so fast when powered by gunpowder in large part because bullets don’t weigh 4,000 pounds like a car does.
You don’t say. Here’s a good illustration of the difference in specific energy density between the two.
Don’t try this at home.