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Theory: Would a "T" DOHC engine config be feasble?

Discussion in 'Other Off Topic Forum' started by Chevarri, Apr 14, 2004.

  1. Chevarri

    Chevarri Formula Junior

    Jan 20, 2003
    764
    In a rose bush.
    Full Name:
    J'aime
    Hello Fchatter perf gurus and other ppl who just like reading and learning. While in class I came up with the idea of having an engine in an upside down T and having it dohc per head, which would be 6 cams! I thought of this idea while I was doodling a car I thought of "self-designed car" A GT, and MR car. Obviously flat engines have been done, inline/straight has been done, but could a "T" engine work? It would be incorporating both worlds of flat and inline. From what I understand about inline 6s and flat 6s are that they are both very well balance engines. Possibilities of pistons would be a 6, 9, and 12. Would this type of eng. config have any benefits over another? What type of downsides could there be whilst in a production auto? This basically is, could it work, and what would be some pros and cons of it?
     
  2. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,992
    Yes, it is possible, being a derivative of the classical radial design (3 cylinders) and adding a dimension of length (inline). However, best balance occurs when the 'T' is a 'Y'.
    Makes for a good airplane engine configuration, does not lead to a low center of gravity for automotive applications.
     
  3. PSk

    PSk F1 World Champ

    Nov 20, 2002
    17,673
    Tauranga, NZ
    Full Name:
    Pete
    VW are currently building close to this concept with their W configuration engines. 4 banks or 2 for their W8 and 4 banks of 4 for their W12.

    This actually has been done as Mitch said with aeroplane engines and I believe such an engine was used for an early Brooklands car called the Napier Ralton ... or something like that, it is a 12 cylinder with 3 banks of 4 cylinders. I think though it was only single overhead cam, if not pushrod (?).

    Pete
     
  4. FrostCS

    FrostCS Karting

    Mar 3, 2004
    65
    Vegas
    Full Name:
    Christopher
    A "T" engine would have both the downsides of a inline, and a boxer engine as well, it would disturb the balance of the boxer or (though different) flat V engine by putting an extra force on the otherwise primarily horizontal motion.
    By downsides I mean, it would be long, tall, and wide. Plus, it would have extra valvetrain weight. Although this doesn't seem like a huge deal, it drains engine power, much like added accessories.
    VW's engine is quite engineous. It involves 4 banks of 3 cylinders (for the 12) and is balanced very well, due to how the engine is layed out. Basically, a 15 degree V6 (very narrow) is mated to another 15 degree V6 at a 90 degree angle. Doing this shortens the length of the V12 to about that of a V8, while still retaining the low engine height of a V engine. It doesn't stop there though.
    Instead of having 8 camshafts you would think it would have (4 per v6 on normal v6's) it has 4 camshafts for the whole engine, reducing the weight of the valvetrain. One Exhaust and Intake camshaft on each side of the engine, and since the V is so narrow, they have it so 1 intake camshaft controls both sets of valves. The same operation is done with the exhaust camshaft. Using this "criss cross" valvetrain on each of the V6 banks may just sound technical, but it's actually a 15% power improvement over using 2 camshafts per bank (8 total), with much less strain on the crankshaft, plus it's cheaper to manufacturer (less parts).
    As Mitch said earlier, to correctly balance a 3 bank engine it would have to be in a "Y" configuration, anything else will leave excess force on one of the horizontal banks of a "T" engine. Though a Y engine would take up much more space then conventional engines.
    CS
     

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