Let's Talk About CGI (Compacted Graphite Iron)

Discussion in 'General Supra Topics' started by Guff, Jul 18, 2018.

  1. Guff

    Guff Moderator
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    Okay, so its learning time here at SupraMKV forums! I wanted to touch on CGI Engine Blocks, a materials technology that many people might not be too familiar with. Why, you may ask? Well, there have been leaks and rumors of the MKV Supra adopting an "Iron" engine block, but I've heard whispers that it's not the "Iron" of yesteryear, but rather, a type of Compacted Graphite Iron, a material that has made significant advances over the old days of heavy cast Iron. I'll try to simplify things as much as I can, as I know materials science can get confusing.

    What is CGI?

    CGI is a type of cast iron developed in the 1950s-60s to be a middle ground between Gray Iron and Ductile/Nodular Iron. Any Cast Iron is made of both Iron and Graphite, and the difference in the makeup and structure of those two elements are what determine the material properties of a given cast iron type. CGI has tightly interconnected graphite molecules that are short and thick in shape. This results in a variety of material qualities that are hugely beneficial in an automotive application:

    -Roughly 400-500% greater fatigue resistance than Aluminum, and ~200% more than Gray Iron.
    -Higher thermal conductivity than other cast irons
    -Great internal damping properties
    -Roughly 50-75% stronger in shear strength than Gray Iron, and can be machined down to match Gray Iron shear strength at significant weight savings.
    -Far more fatigue resistant than Aluminum in higher temperatures.
    -Due to CGI's high strength, it can technically be machined to be lighter than aluminum while maintaining the same strength levels (although generally, CGI blocks are not machined this far in order to keep strength levels high).

    Who uses CGI?

    CGI is used by a number of OEMs, namely Ford and, of course, BMW. Their exact material compositions are generally different, but they are generally comparable in strength. Toyota also uses CGI in their Nascar program, with their V8s being cast from CGI.

    The disadvantages of CGI are generally in machining and manufacturing, which is where having access to OEM levels of tooling is hugely important, and can both streamline the manufacturing process and reduce costs.

    So, is the MKV Supra using CGI in its motor?

    Idk, ask Tada-San. :p

    From what I know, we're not getting a plain jane B58. What exactly is this new motor? I don't know, but as more information trickles in, the BMW-Toyota partnership starts to make more sense. CGI is one of those factors that could really shed some light on the nature of the Toyota-BMW relationship, and also shows that there's a lot more than meets the eye when it comes to orchestrating the millions of moving parts in a collaboration as big as this.

    leavetheironon-inline3-photo-587201-s-original.jpg
     
  2. ginsuown

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    So the new supra's engine is going to be more substantial than just some movie magic..

    But actually though, I'd been seeing mentions of this CGI in the new engine and been wondering exactly what it was. Thanks for the post and the good info Guff :)
     
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  3. RyleyMA61

    RyleyMA61 Well-Known Member

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    My understanding is that it's the medium ground between grey cast iron and ductile cast iron.

    I'm assuming that the JZ blocks were cast grey iron?

    Also more science!!!
     
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  4. Matador

    Matador Well-Known Member

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    Toyota's newer diesel V8s are also cast with CGI.
     
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  5. Chikane

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    Man I turn on Adobe creative cloud and everything. I want my money back. Jest aside thanks for the lesson Guff this was enlightening.
     
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  6. A70TTR

    A70TTR Well-Known Member

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    #6 Jul 18, 2018
    Last edited: Jul 18, 2018
    JZ blocks are gray cast iron iirc

    ^ was not aware of that and could not find any information on it? Any links for some good reading?


    EDIT: found, Toyota 1VD-FTV. neat!
     
  7. Jeff Lange

    Jeff Lange Well-Known Member

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    Love the Toyota VD diesels. One day...

    Jeff
     
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    Guff

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    Yup, CGI is generally used in diesel applications for its higher strength to handle the higher cylinder pressures. Ford also uses CGI in some of their TT V6s, but in a far more clever way than one might imagine. The main section of the block is casted from CGI (Cylinders, core structure, main caps, etc) but everything underneath that is cast aluminum. This allows for high strength CGI exactly where its needed, and lighter aluminum where something less strong can do the job. It's an interesting way to do it, but does present potential assembly/manufacturing issues, as well as potential reliability/longevity concerns, due to the mating of two different materials in such a critical location. That's why Ford pays the big bucks to its engineering department though!

    leavetheironon-inline2-photo-587199-s-original.jpg
     
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  9. A70TTR

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    yeah, ford said that they felt aluminum was not a sufficient material by itself when using forced induction.

    I actually like Ford quite a bit, at least WAY more than GM and FCA.
     
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  10. Matador

    Matador Well-Known Member

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    Didn't realize this. That's quite an awesome bit of engineering there. Hats off to Ford.
     
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    Guff

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    Doing some more research onto Toyota's 1VD-FTV diesel engine, I found that Toyota claimed that the CGI block was "75% stronger and 30% lighter" than the previous iron casting. Here's a direct quote from the press release for that gen of Land Cruiser:

    "CGI is light, withstands wear and corrosion, and is very resistant to heat and shock. By using it for the cast iron cylinder block, Toyota has reduced noise and saved significant weight when compared with equivalent engines."
     
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  12. Nurburgring

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    #12 Jul 18, 2018
    Last edited: Jul 18, 2018
    A nice choice of material to cover the wildly different crowds the Supra must try to please:
    - A80 owners: "It must make at least 3000hp on stock block and rods for me to consider this car"
    - GT86/Miata/S2000 owners: "what an overweight pig! it`s only designed to go fast in a straight line?"

    For reference, Audi saved 10kg on its 3.0-liter V-6 TDI diesel engine by moving to CGI. Every kg counts.
     
  13. supraboi

    supraboi Well-Known Member

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    https://www.bimmerboost.com/showthr...e5c63eb7605243e8273782656&p=803243#post803243
     

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