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    • Toyota rumored to give the BMW B58 engine a CGI (compacted graphite iron) engine block

      Have you ever heard of CGI engine blocks? You are not alone. It means the block is made out of compacted graphite iron which offers properties that are stronger than aluminum but lighter than iron. The application of CGI blocks is gaining popularity with diesel motors.


      A rumor floating around is that Toyota will design an iron block for their B58 I6 turbo variant going into the MKV Supra. Now, that is likely false. What is getting lost somewhere in the translation is that the block could be CGI.

      Now, this is a rumor so do not get too excited but it would definitely set the Supra apart. Assuming the rumors built on snippets from Toyota engineers are true that would mean the B58 could take a hell of a lot of boost. This would be a nod to the MKIV Supra and its practically legendary tuning reputation which Toyota is obviously aware of.

      It would also mean BMW B58 owners would not have to sleeve their own aluminum block or necessarily reinforce it if going for big power. Toyota already did all the work and they could simply swap to the factory CGI block which would be superior.

      Taking this even further it would mean S58 owners (next gen G80 M3) would have an off the shelf block solution as well should they go chasing huge power figures.

      Will it happen? Only Toyota and BMW know that. If it does, the MKV Supra will indeed be special.

      This brings us to one of the newer, more exotic iron alloys, compacted graphite iron (CGI). This new type of cast iron was invented back in 1949, about the same time ductile cast iron as discovered. For many years, nothing much came of CGI because it was not quite as strong as ductile iron. But it was 75 percent stronger and up to 75 percent stiffer than gray cast iron. This meant an engine block could be made up to 20 percent lighter than a standard gray cast iron block a perfect solution for reducing weight or making a block stronger to handle more horsepower.

      Though still much heavier than aluminum, CGI has five times the fatigue resistance of aluminum at elevated temperatures, and twice the resistance to metal fatigue as gray cast iron. When used in a diesel engine or a racing engine, it can provide a significant savings in weight.

      Many Caterpillar engine components are being switched to CGI, such as modular heads, and Audi is using CGI in their 2.7L, 3.0L V6 and 4.0L V8 diesel engine blocks. The BMW Series 7 V8 engine is also CGI. Even Hyundai is now producing some CGI blocks (2007 Veracruz).

      One aftermarket supplier of engine blocks said CGI is a good upgrade for performance applications where high levels of nitrous oxide or turbo boost are being used. The added strength provided by CGI has no weight penalty, but typically adds about 40 percent to the cost of the block over gray cast iron.

      Machining CGI is a little more difficult than gray cast iron because of the increased hardness of the material. Coated CBN works well, but tool wear is accelerated and feed rates may have to be slowed to achieve the same surface finish.

      This article was originally published in forum thread: Toyota rumored to give the BMW B58 engine a CGI (compacted graphite iron) engine block started by Sticky View original post
      Comments 12 Comments
      1. subaru335i's Avatar
        subaru335i -
        Still heavier than aluminum block. In a supposedly lightweight balanced sports car it wouldn't help the driving dynamics unless they change a bunch more things in the turbo variant.

        Would be cool but I really don't buy it.
      1. BlackJetE90OC's Avatar
        BlackJetE90OC -
        Well there is no denying it is a B58 variant from the pic. I do see some differences, like airbox, coolant expansion tank, etc...(all down to packaging differences new chassis).

        The charge pipe looks beefier and the throttle body is clocked at a much different angle(does that mean bespoke intake manifold).

        Click here to enlarge
        Click here to enlarge
      1. 93siro's Avatar
        93siro -
        BS
        They don’t care about aftermarket and no sane person would do a iron block straight 6 anymore with the technological advances we got with castin aluminums.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 93siro Click here to enlarge
        BS
        They don’t care about aftermarket and no sane person would do a iron block straight 6 anymore with the technological advances we got with castin aluminums.
        That's why CGI is mentioned...
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by subaru335i Click here to enlarge
        Still heavier than aluminum block. In a supposedly lightweight balanced sports car it wouldn't help the driving dynamics unless they change a bunch more things in the turbo variant.

        Would be cool but I really don't buy it.
        BMW made their name with iron block I6's and had 50/50 weight distribution so what are you talking about?
      1. subaru335i's Avatar
        subaru335i -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        BMW made their name with iron block I6's and had 50/50 weight distribution so what are you talking about?
        Those platforms were made with the iron block from the start. The Supra is still a BMW derived chassis right? and they are claiming the BMW will have a normal aluminum B58 so to make it still balanced with the CGI block it would be even more work. These types of partnerships aim to reduce the differences as much as possible to keep developmnet costs down. Why on earth would they spend the time and money to not only redesign the block to a more expensive hard to machine CGI and change the chassis balance for literally no benefit to the OEM.
        Cast aluminum blocks are more than strong enough to hold up to any OEM power Toyota or BMW will throw at them.
      1. BlackJetE90OC's Avatar
        BlackJetE90OC -
        Click here to enlarge Originally Posted by subaru335i Click here to enlarge
        Those platforms were made with the iron block from the start. The Supra is still a BMW derived chassis right? and they are claiming the BMW will have a normal aluminum B58 so to make it still balanced with the CGI block it would be even more work. These types of partnerships aim to reduce the differences as much as possible to keep developmnet costs down. Why on earth would they spend the time and money to not only redesign the block to a more expensive hard to machine CGI and change the chassis balance for literally no benefit to the OEM.
        Cast aluminum blocks are more than strong enough to hold up to any OEM power Toyota or BMW will throw at them.
        It is being speculated the mules running around with cgi block and higher flowing head could be GRMN model(aka Toyota's M-version). Supposedly the engine has been tested up to 700hp. It would be similar to N55 open deck block in base car vs S55 closed deck block in the M-car(where M-car used a heavier more robust block regardless if it added weight). Tada has said the Supra debuting early next year will have no carbon parts, it is all aluminum/steel to keep it affordable. So with the use of carbon like the carbon packages on Lexus, that could then offset weight from cgi block in GRMN model.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by subaru335i Click here to enlarge
        Why on earth would they spend the time and money to not only redesign the block to a more expensive hard to machine CGI and change the chassis balance for literally no benefit to the OEM.
        To differentiate it.

        I wouldn't expect a CGI block to be so heavy they couldn't keep it 50/50 when going to a more rigid and lighter coupe chassis anyway.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by BlackJetE90OC Click here to enlarge
        that could then offset weight from cgi block in GRMN model.
        That means 4 Supra Models?
      1. leveraged sellout's Avatar
        leveraged sellout -
        I'm very confused as to why the **** everyone keeps referring to the Supra as if it was some sort of Honda S2000 clone.

        It was never that. It will never be that. Go buy a BRZ. The last Supra was a big, heavy, expensive GT car. And it happened to handle fairly well too. If anything, the new car will be a bit less "GT" than I would hope, if all the rumors are true.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        The last Supra was a big, heavy, expensive GT car.
        Yep but now they're going to a sporty coupe...
      1. BlackJetE90OC's Avatar
        BlackJetE90OC -
        Click here to enlarge Originally Posted by leveraged sellout Click here to enlarge
        I'm very confused as to why the **** everyone keeps referring to the Supra as if it was some sort of Honda S2000 clone.
        Probably because Chief Engineer keeps referencing the Cayman as it's handling benchmark.

        This Supra is going to be a sports coupe, not a GT car.

        Honestly... just think of it as Z4M Coupe designed/engineered by Toyota, with a B58 tweaked by Toyota/Yamaha.