Why did Soviet tank engines have such large displacements?

Discussion in 'Weapons, Technology & Equipment' started by Dave55, Mar 30, 2017.

  1. Dave55

    Dave55 Atlanta, USA Patron

    I was looking at BT-7 specs and noticed that the Milulin M-17 V12 had a displacement of 46.9 L (2,864 cubic inches), four times more than a Panzer III engine.

    The T34 diesel displaced 38.8 liters.

    These seem pretty big compared to the Tiger's 23 liter Maybach, Meteor's Merlin based 27 liter or the Sherman's 18 liter Ford V8

    Any thoughts?
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  2. von Poop

    von Poop Adaministrator Admin

    Never really thought about it.
    Pre Tdi - much bigger lumps required for tank-moving power?
    Bigger lump: more protection?
    Compensating for rough production?
    Diesel heritage meaning marine motors as starting point?
  3. CL1

    CL1 116th LAA and 92nd (Loyals) LAA,Royal Artillery Patron

  4. Harry Ree

    Harry Ree Very Senior Member

    Somewhat detached from an understanding of thermodynamics involving steam cycles

    I think generally that given a petrol driven engine and a diesel powered engine have equal engine capacity,the petrol engine will have a greater power output as expressed in HP,PS or KW than the diesel engine.May be due to the petrol engine having a higher top temperature in its combustion cycle....another factor would be the exhaust temperature...this would determine the power output and efficiency.

    The Russian petrol fueled M17 V12 engine may not have had an efficient combustion cycle resulting in the power output/cylinder and hence total output being lower than a petrol engine of the same size having a a more efficient combustion cycle.

    A good comparison for a current model.... a Ford Mondeo petrol 2 litre engine has a power output of 240 PS (metric HP.)

    The Ford Mondeo two litre TDC1 diesel engine has a power output of 150 PS (metric HP)
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  5. von Poop

    von Poop Adaministrator Admin

    The thought occurs, despite the fact I think it's probably mostly about diesel, that given the same engine eventually went into beasts like the SU152 and IS2, there was a certain logic there.

    You don't quite have the technical sophistication of the Germans (and British, thinking about the meteor) for complex or compact high-output lumps.
    You also don't have the same wide, sophisticated (and some might say... initially slightly confused) industrial base of the US to innovate things in a hurry.

    What you do have, is a centrally planned economy with a heavy industrial base. An economy that was always paying some attention to military needs, despite the putsches etc.
    In planning, and even cooperation with Germany at Kazan etc., it must have been fairly apparent they couldn't match the sophisticated engines, but had more than enough resources to plump for safe, solid, powerful by virtue of simple large displacement lumps that would be well within manufacturing capability while giving an element of future-proofing.

    T35 also springs to mind here.
    A nation that was playing with the idea that land battleship might be the future of tanks, could be excused for thinking some seriously whopping power-plants might be a good idea. T35 ran on a licensed Beemer aviation engine and was somewhat anemic.
    Soviet solution: bigger and simpler...
  6. Harry Ree

    Harry Ree Very Senior Member

    Regarding efficiency, I do not think that Russia would see efficiency as the priority in the design of engines since there were more than adequate fuel supplies available in Russia.Striving for efficiency would not be in their tank design envelope if it affected reliability.Simple designs tend to return reliability while avantgarde design practices run the risk of generating functional problems and possibily adversely affecting the use of the gear,especially on the battlefield

    Modern engineering design has been fine tuned so that commercially and militarily.the philosophy of designers of heat engines across the wide range of heat cycles is one of RAM....reliability,availability.maintainability.

    It is recorded by Russian tank crews that they preferred diesel engines in their tanks so much so that Shermans were supplied to Russia in both petrol and diesel versions
    Last edited: Mar 31, 2017
  7. Dave55

    Dave55 Atlanta, USA Patron

    I learned that the Milulin M-17 was a copy of the BMW VI V12.

    Here is one running in a racing car:

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