Comment on Rumored 'Big-Block' Duramax Diesel Could Be 8.3L and We’re Off the Rails Now

• GiveMemes@jlai.lu ⁨7⁩ ⁨months⁩ ago

  If you don’t understand mechanical engineering and take your own knowledge of engines as being better than the calculations of literal engineers…

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  • schnokobaer@lemmy.ml ⁨7⁩ ⁨months⁩ ago

    Damn I could’ve sworn I’ve studied that for 6 years and am an actual mechanical engineer! To be fair I’m not working in automotive anymore but I have trained as an automotive mechatronic before majoring ME.

    I’m also wondering what calculations I’m supposed to doubt here, it’s literally a rumoured engine, no specs other than a displacement that could(!) be 8.3L, no emission data, to performance data. I’m just calling out that author’s claim that they made it bigger so it has less emissions. It’s obvious marketing bullshit he’s parroting. They were forced to, among other things, reduce compression due to emission laws and the resulting engine is inevitably less efficient, so they (could!) made it bigger to negate the efficiency losses and still be able to have a new model with more horsepower than the last one, despite having a less efficient ICE, obviously at the cost of fuel economy and all other emissions but nitrogen oxides. Not that it matters to their customers but that’s what it is, and only a marketing department could come up and twist this into something positive they have thought of to tackle emissions. And stop it with this engineers’ calculations bs, this shit isn’t even technical. NOx formation is far more complicated than just being a function of compression, it’s affected by how hot a mixture burns, determined by how gradual and geometrically even the combustion takes place and how much volume of the chamber is utilised or whether it concentrated to a specific region. Cylinder head geometry and injector design and actuation play just as big a role as compression (which really is a beneficial side effect to modern injector design that lead to a more efficient combustion.) They could’ve just reverted all that lean-burn technology (obviously not lean-burn for a Diesel but it’s the same philosophy) and sold the car with slightly less NOx emissions, but that’s not what this is about. It’s about marketing not being happy about an engine with less horsepower, so they let them build it with more displacement and made up a story of how they made it bigger so it could emit less NOx. They know dense people will buy that.

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