Last Call: Twin Six Edition

gmc v12
There’s no better way to cap off the week than with some engine pron, I always say. The GMC Twin Six wasn’t really two V6 engines welded together but one honkin’ big V12 displacing 702 cubic inches and a forged crankshaft that tipped the scales at a robust 180-pounds. Pop that into the engine and add all the rest of the accessories and you’re looking at 1500-pounds for this torque monster. GMC built about 5,000 of these monsters.
Last Call indicates the end of Hooniverse’s broadcast day.  It’s meant to be an open forum for anyone and anything. Thread jacking is not only accepted, it’s encouraged.
Image: Go Away Garage

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  1. CraigSu Avatar

    Which vehicles were produced with this engine? From the sign in the background they were clearly installed in trucks. Must have been big ones.

    1. smalleyxb122 Avatar

      Optional engine in early ’60s GMC commercial trucks. Not many takers.

    2. Batshitbox Avatar

      The Blastolene B702 was produced with a Twin Six. The engine’s displacement is right in the name.

  2. Fuhrman16 Avatar

    While it may not have been two welded together V6s, it did use four cylinder heads, four exhaust manifolds, and two intakes from their V6 engine line.

    1. outback_ute Avatar

      Yes not welded but definitely two V6s joined together (obviously without two timing chains etc), just like the Aston Martin V12 although that doesn’t share as many V6 parts as this! It is probably worth noting from a modern perspective that this was near the end of the era of semi trucks running gasoline engines.
      This is also pretty common in large industrial diesel engines that have individual cylinder heads, they are made from 3 cylinders up to 48 cylinders (in a very) depending on how much power is needed.

  3. Sjalabais Avatar

    In the current climate of extreme engine swaps, would it be feasible to throw this monster into a GM product that weighs about 1500 pounds engineless?

    1. Frank T. Cat Avatar
      Frank T. Cat

      You’d have to seat the driver on the roof.

      1. CraigSu Avatar

        Given that you’re doubling the weight of the vehicle adding a flying bridge wouldn’t really mess with the center of gravity too much. Then you’d probably have a mini version of another Grubb creation, the Decoliner.

  4. jim Avatar

    -So, it’s time to decide how we’re going to advertise our new lineup of vans. Any idea ?
    -A happy family ready for vacation?
    -Nah, boring.
    -A young, sporty couple loading some camping equipment ?
    -How about some creepy, straight-out-of-your-nightmares clowns ?
    -That’s exactly what i was looking for ! Give that guy a promotion !

    View post on

    1. Batshitbox Avatar

      I think that’s Sarah Palin’s campaign bus.

      1. Sjalabais Avatar

        Needs more guns.

    2. I_Borgward Avatar

      If you took all of the clowns and stuffed them into an Econoline, I wouldn’t be a bit surprised.

      1. dead_elvis Avatar

        Let’s weld the doors shut once they’re all inside. Please.

    3. dead_elvis Avatar

      I didn’t want to sleep for the next few nights anyway.

    4. nanoop Avatar

      “Club / Custom / Chateau”? Chapeau!

  5. Batshitbox Avatar

    Tom Jones’ cover of Gillian Welch’s Elvis Presley Blues is kind of psychedelic. It reminds me of Scott Walker’s turn to the avant garde in the ’80s. (This has nowt to do with cars.) (Let’s try a Vevo imbed…)

    1. Batshitbox Avatar

      Nope. I thought Disqus allowed those? Luckily you can get Vevo on Youtube

      1. dead_elvis Avatar

        That’s an extremely weird take on a song that I love.
        Sounds like he’s channeling Bowie at a couple of points.
        Edit: Beats the hell out of Jimmy Buffett’s version. I won’t link it here, because I think Buffett should be locked in a van with the rest of the clowns.

        1. Batshitbox Avatar

          I only found out there was a Jimmy Buffett version today, while trying to find the proper songwriter’s credit. I didn’t bother listening to it.
          But, Hey! Gillian Welch and David Rawlings are my age, and that’s a little too young to have really experienced the career of Elvis Presley first hand. Tom Jones is just 5 years younger than Elvis, and Jimmy Buffett, at 10 years younger, is about the perfect age to have been hit hard by the Elvis phenomenon. I find it easier to understand Jones and Buffett singing it than Rawlings and Welch writing it!
          Maybe someone born 30 years after Michael Jackson (that’d be the late ’80s) is about to write a song that Sting and John Mellencamp will cover.

    1. Sean McMillan Avatar
      Sean McMillan

      somewhere on the web I saw some in cab footage of the above truck being flung around a muddy horse racing track. It looked wicked fun.

  6. wunno sev Avatar
    wunno sev

    weeeelp. i just put my money where my mouth is, and purchased a brand-new Fiesta ST.

    1. Sjalabais Avatar

      Is that even allowed? 🙂 Great choice – congrats! How long til you…:

      1. gerberbaby Avatar

        Looks like a riot. How does he not have any brake fade? Those pads must be glowing.

      2. CraigSu Avatar

        Maybe if he wasn’t wearing hiking boots for the demo he might have more feel for what he’s doing. Regardless, that’s mighty impressive, looks like a blast.

        1. Sjalabais Avatar

          Absolutely! I change shoes just for driving along ordinary traffic…nowhere nesr those skills anyway.
          But this was about WS’s Fiesta – looking forward to see some photos!

  7. outback_ute Avatar

    I came across a Bugatti Royale replica/hot rod that used one of these – note this is 77 cu in smaller than the original Bugatti engine!