This is Why Cars Aren’t Powered by Gunpowder

A rifle bullet with gun powder isolated


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.


  1. avatar cmac890 says:

    This does beg the question of why we don’t put gasoline in bullets, though.

    1. avatar DesertDave says:

      In a word, Oxidizer.

      1. avatar Spectre_USA says:



        Good answer!

      2. avatar Mr. Rigors says:

        “In a word, Oxidizer”

        and can you say ‘Catalyst’? How ’bout Tetra-Nitro-Toluene? Or maybe something simple like ‘re-fried beans’.
        I knew you could.

    2. avatar J says:

      Gasoline expires in a couple of months.

      1. avatar I Haz A Question says:

        It reliably lasts up to two years if treated and sealed. I’ve been rotating gas cans on a 12-month schedule for many years. Fill up a 5-gal can, add some Sta-Bil, seal it and keep it in a cool place. Put it into your car’s tank a year later with no problems whatsoever. Properly stored diesel can last even longer.

        It’s the added butane content that “expires” over time. Cheap gas has poor butane content.

      2. avatar tmm says:

        I wonder if that would be “gasoline” or “gasoline and ethanol-related product via federal mandate.”

        1. avatar jwm says:

          When I was young we drained all the gas out of things we stored for the winter. Lawnmowers. Rototillers. That sort of stuff. Had never heard of ethanol and we had leaded gas back then.

          If you didn’t drain you had a mess to sort out come spring.

        2. avatar Rattlerjake says:

          jwm – The reason for removing the gasoline over winter is because gasoline attracts water from the atmosphere, so by springtime you would need to empty the can tank and flush the fuel system to remove the water. Plus the water causes corrosion.

          I often buy “new” lawn equipment, generators, etc. in the spring, really CHEAP, because people can’t get them running, not knowing that they have water in the fuel.

    3. avatar gary moore says:

      Blew up R G 38 some parts were never found, when I was 16 1958

    4. avatar Person says:

      Good idea

  2. avatar I Haz A Question says:

    Guy with the jacket looks like he could be Dirty Harry’s nerdy cousin who calculates all the energy Harry’s .44 Auto Mag expends when sending bad guys into the hereafter.

  3. avatar Tom in Oregon says:

    “Don’t try this at home”

    Hold my beer. I use hair spray in my tennis ball/potato launcher.

    1. Me too. Never had a problem.

      1. avatar CTstooge says:

        Aqua-Net rules!

        1. avatar Tom in Oregon says:


    2. avatar Geoff WWJWD - "What would John Wick do?" PR says:

      You need to make your next one from proof *steel*.

      Or be like the guy at ‘Farm Craft 101’ and convert all your scrap brass into a *cannon* :

    3. avatar Cucamonga Jeff says:

      Starting fluids, like ether are much more entertaining.🔥🔥🔥🔥🔥

      1. avatar I Haz A Question says:

        That’s what I use. Never used hair spray, as aerosol starter fluid packs a lot of punch. We used to break open those Cyalume glow sticks and cover potatoes with glow-in-the-dark green goo, then launch them at nighttime from the beach into the ocean.

        Wonder why the ATF doesn’t go after all the potato launchers as AOWs, lol.

        1. avatar DavidT says:

          Don’t give them any bright ideas. They cause enough damage on their own.

      2. avatar Jr says:

        Propane, with a metering chamber. Not the absolute most powerful combustion fuel but it’s by far the most reliable, repeatable, and consistent.

    4. avatar Bob in IN says:

      I used lighter fluid. oh the days of metal tennis ball cans.

    5. avatar Craig in IA says:

      “Don’t try this at home” Of course not- do it at your neighbor’s place…

  4. avatar Guesty McGuesterson says:

    When I was a kid, one summer day I noticed wasps entering a hole in the brick wall separating our back yard from our neighbor’s, and heard a lot of buzzing inside. Being an adventurous fellow, I poured an entire cup of gasoline (parents weren’t home at the time) to take care of the problem. Thinking I was leaning on the side of safety, I got things mixed up in my head and mistakenly thought that *liquid* gasoline was explosive, so I waited a minute to allow it to evaporate inside the wall. I lit a match, tossed it toward the wall’s small hole, and turned my face away just in the nick of time as the explosion cracked the wall and blew some of the top caps off.

    Dumbest thing I did that summer, but the wasps were gone and the neighborhood kids who were watching nearby thought I was a hero.


    1. avatar AD says:

      The wasps were gone…. Nuff said.

  5. avatar Green Mtn. Boy says:

    No chit !

  6. avatar Narcoossee says:

    Nobody needs something with the power of 46.4 megajoules per kilogram!


    1. avatar I Haz A Question says:

      Especially if it’s cheap “Saturday Night Special” gas in a black can with scary accessories.

  7. avatar tmm says:

    Gasoline, on the other hand, sits at a whopping 46.4 megajoules per kilogram

    Doc Brown?

  8. avatar Richard says:

    The video was from ‘The Secret Life Of Machines’ that was on Discovery Channel 20-some odd years as go; back when they opened your mind with scientific geared programs instead of aliens.
    Now it’s basically the conjecture and propaganda channel.

    1. avatar Xanderbach says:

      I loved that show. The “internal combustion” episode, which this video is from, is an all time great.

    2. avatar Knute(ken) says:

      This episode was my favorite. Its on the light bulb.
      Its also a playlist of every episode, including the I.C.E. and the car. The one on TV is really surprising. Its where I learned that Britain had TV early in the 1930’s but the US had to wait for twenty+ more years. Corporate America wouldn’t let it become known until the inventor of TV (Philo Farnsworth) died, so that they could steal it. Who knew?

    3. avatar Southern Cross says:

      I remember that show. Brilliant! And available for free download but the quality is VHS at best. Even the one on sewing machines was very interesting.

      1. avatar Knute(ken) says:

        Wasn’t it though? I’d always wondered how the bottom thread got through the loop left behind by the needle. Them using a whole crew to do it by hand on two big sheets of Styrofoam made it all perfectly clear. Brilliant way to show it clearly in a few seconds.

  9. avatar Mikkidog says:

    Who’s going to invent a gun with Liquid Oxygen tanks now?

    1. avatar Rocket Raccoon says:

      Remember those fabled white flamethrowers from Elon Musk’s The Boring Company? I was mountain camping a few months ago, and some college guys were setting up their campfire in a nearby site. One of them busted out one of those actual flamethrowers and lit that sucker up. I was so enthralled, I walked over to ask if it was the genuine article.

      Long story short, it was, and the proud owner allowed me to use it to start the next evening’s campfire. Pretty fun stuff.

      1. avatar Geoff WWJWD - "What would John Wick do?" PR says:

        All that 300-whatever dollar flamethrower that Musk was selling is, is a re-packaged propane torch you use for burning weeds :

        Make your own with a Nerf gun of some sort and save yourself 200 bucks…

  10. avatar KenW says:

    How about a car propelled with Project Orion tech?

  11. avatar daveinwyo says:

    And they want to propel a spacecraft with nukes.

  12. avatar Hank says:

    There was actually one, strange, coal powered car in the 1970s, invented by GM, I think. It was invented due to the gas shortage and GM wanted to produce a car quick that didn’t rely on gas at all. They only made a handful I believe and were extremely loud and belched black smoke like a 1800s locomotive.

    1. avatar KenW says:

      Then there were the wood gas powered vehicles.

      1. avatar daveinwyo says:

        During WWII, in England and,I think some places in the US, cars (autos) had a gas bag on the roof filled with coal gas.

        1. avatar meh says:

          “Construction of a Simplified Wood Gas Generator for Fueling Internal Combustion Engines in a Petroleum Emergency”. FEMA lnteragency Agreement Number: EMW-84-E-1737 Work Unit: 3521 D.
          Published: March 1989

    2. avatar Anymouse says:

      Stanley made external combustion engines car (Stanley Steamer) that burned gas and kerosene, but the concept could be extended to wood or coal.

  13. avatar RGP says:

    What about the old radial engines on some aircraft that were started using a 12 gauge blank? Example, Hellcat. A 12 gauge blank isn’t a lot of powder and a P&W R-2800 is a hell of a lot bigger engine than you’re likely to find in a car.

    1. avatar Geoff WWJWD - "What would John Wick do?" PR says:

      ” A 12 gauge blank isn’t a lot of powder and a P&W R-2800 is a hell of a lot bigger engine than you’re likely to find in a car.”

      Gunpowder works its magic because it converts its energy into a nearly-instantaneous volume of very high-pressure gas…

    2. avatar Big Bill says:

      The Hellcat used an R-2800 that has an electric starter, not a Coffman starter.

  14. avatar Mad Max says:

    So, why is smokeless powder a hazmat for shipping when motor vehicles carry quite a bit of gasoline through hazmat-prohibited routes?

    1. avatar Geoff WWJWD - "What would John Wick do?" PR says:

      The burn rate is far faster with firearm propellants, and they package their oxidizer in the powder itself…

  15. avatar Jericho says:

    Jalopnik is a shitheel site owned and operated by the same people as the Root, Gizmodo, Deadspin and i09. Shills and antigunners.

  16. avatar Sean G./The Rookie says:

    I can’t help but be reminded of this old chestnut:

    Man, I wish I could have been there to see that…

  17. avatar keep yur paws off my dead guy" possum says:

    It’s really not a Neutrino Fusion Blomb, I’m condensing Neutrinos into liquid. I just painted MAKING BLOMB HERE, on the side if the barn to keep the Feds off my ass. If they knew I was making a better substitute for gasoline, why, why , they’d just kill me.

    1. avatar Big Bill says:

      The feds wouldn’t mind much, actually.
      It’s Exxon you’d need to worry about, and they have a LOT more money than the feds.

      1. avatar "keep yur paws off my dead guy" possum says:

        Yeah Exxon, they can call in a whole Army

  18. avatar FlyingFish says:

    “gunpowder, at best, has a specific energy density of 11.3 megajoules per kilogram”
    And a good thing too. As an adolescent I was fond of making black powder in the basement and experimenting with it. That is until my father confiscated the saltpeter. Thus, I went on to experiment with other homemade rocket fuels including homemade hydrogen. Luckily by the time I learned about how to make nitrocellulose I was a little more mature. (This is gun related, right?)

    1. avatar FlyingFish says:

      Hydrogen doesn’t stink nor make a cloud of smoke so I could play without being found out.

    2. avatar adambomb286 says:

      Pleased to meet you Mr. Hickam, I love your books!

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