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    • BMW B58 cylinder head offers terrible flow? HeadGames flow benches MKV Supra cylinder head

      HeadGames is well known for their performance cylinder head work on this network. Recently they got a hold of a BMW B58 cylinder head from a MKV Toyota Supra. We did not get the full flow bench figures but did get some interesting insight.


      @HeadgamesDave stated the following:

      will say it's the worst cylinder head in terms of flow ever on the flow bench
      That is hardly a ringing endorsement of the head.

      The truth is in the turbo era BMW cylinder head flow has not improved. The reverse actually occurred as with forced induction BMW is not striving to squeeze out every last horse as they did with naturally aspirated motors.

      On the bright side this means HeadGames should be able to find considerable gains in the head. We also got a small CFM flow teaser and take it for what it is worth:


      It might be interesting to compare the B58 3.0 cylinder head flow figures to those of another German factory boosted 3.0 six-cylinder. If HeadGames would like to do so, BoostAddict would be happy to provide the cylinder heads off our Porsche 991.2 Carrera project car.

      This article was originally published in forum thread: BMW B58 cylinder head offers terrible flow? HeadGames flow bench MKV Supra cylinder head started by Sticky View original post
      Comments 17 Comments
      1. 93siro's Avatar
        93siro -
        I thought HeadGames said average Joe can not comprehend head flow numbers therefore they won’t post any? Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 93siro Click here to enlarge
        I thought HeadGames said average Joe can not comprehend head flow numbers therefore they won’t post any? Click here to enlarge
        They haven't changed from that position...
      1. maxnix's Avatar
        maxnix -
        If HeadGames would like to do so, BoostAddict would be happy to provide the cylinder heads off our Porsche 991.2 Carrera project car.

        Much larger valves from an oversquare engine. They do have flow numbers for N54 and S55, do they not? Would be interesting to see a before and after porting percentage flow comparison between the heads.
      1. Flinchy's Avatar
        Flinchy -
        >is well known for their performance cylinder head work on this network

        Who?

        Not too surprised it flows poorly especially on the exhaust... But to be fair, it's the same as measuring post turbo manifold, which no one does, apples to slabs of concrete comparison?
      1. CobraMarty's Avatar
        CobraMarty -
        Head on bench is testing the intake side.
        Remember these B58 engines/heads have the smallest bore diameter- 82mm, and smallest intake valves size- 30mm, of the various 3L engines, N52, N54, N55 and B58.

        185cfm on a 30mm valve is not spectacular when compared to 34-37mm intake valves. Very few engines run this small of intake valve diameter. Check out Mini heads for comparison.
      1. Torgus's Avatar
        Torgus -
        The next 2JZ this is not.
      1. CobraMarty's Avatar
        CobraMarty -
        Look at this Mini head. Stock head has 29.8mm intake valve.

        Click here to enlarge
      1. CobraMarty's Avatar
        CobraMarty -
        Attachment 59554
      1. hardparker's Avatar
        hardparker -
        An N55 head flows 164 cfm stock, 217 with porting. Looks like the B58 head flows better than a stock N55 at least.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by maxnix Click here to enlarge
        Would be interesting to see a before and after porting percentage flow comparison between the heads.
        Exactly. Would love to see them compared.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Flinchy Click here to enlarge
        Who?
        HeadGames? They provided the first S55 solution for high powered F80's and F82's?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by hardparker Click here to enlarge
        An N55 head flows 164 cfm stock, 217 with porting. Looks like the B58 head flows better than a stock N55 at least.
        That's on the intake side?
      1. hardparker's Avatar
        hardparker -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        That's on the intake side?
        Yeah, intake side. Exhaust 162 stock, 178 ported. The exhaust side of that B58TU head with only two exhaust ports won't lend itself well to porting.
      1. bnks334's Avatar
        bnks334 -
        Click here to enlarge Originally Posted by hardparker Click here to enlarge
        Yeah, intake side. Exhaust 162 stock, 178 ported. The exhaust side of that B58TU head with only two exhaust ports won't lend itself well to porting.
        I'd guess the headifold isn't as much a restriction as first assumed. It's like having a built-in log style manifold. Eliminates a lot of packaging constraints in regard to port size and spacing. Porting the outlet will probably help at higher power levels. Lets see someone slice it open... Also, bench flow numbers can vary wildly. Need both heads on the same test rig back to back to get a better comparison.
      1. CobraMarty's Avatar
        CobraMarty -
        On the exhaust side you can 'pocket port' it and open the 2 outlet ports.
        And then there is always 'Extrude Hone'.

        The 'headifold' is like using a SteedSpeed exhaust turbo manifold with even shorter runners and no leak prone manifold gasket.
      1. CobraMarty's Avatar
        CobraMarty -
        Interesting looking at the Mini head numbers. For the stock head with nearly the same size intake valve as the B58 head, we see-
        0.25" (6.35mm) lift- 163cfm
        0.30" (7.62mm) lift- 178cfm
        0.35" (8.89mm) lift- 178cfm
        0.40" (10.16mm)lift- 179cfm

        The stock Mini intake port really runs out of CFM flow at much anything over 0.25" lift (6.35mm).
        With porting on stock valves it picks up +20-30cfm, and with slightly bigger valves it picks up +30-40cfm.

        I'm sure the B58 head will see similar results with intake 'pocket porting' as the Mini with about +30cfm on stock size valves.

        Now with a MILVS modification, you would see +1mm additional intake valve lift and +2-3* more duration.
        Even though the CFM flow flattens out with additional lift, there will be more 'area under the intake valve lift curve', so more time for additional air to flow into the combustion chamber and more power.

        0.25" (6.35mm) lift
        0.30" (7.62mm) lift
        0.35" (8.89mm) lift
        0.381" (9.70mm) lift Maximum Stock intake valve lift
        0.40" (10.16mm) lift
        0.421" (10.7mm) lift- NEW Maximum Stock intake valve lift with MILVS modification.
      1. CobraMarty's Avatar
        CobraMarty -
        For a visual of what I'm talking about, check out this picture. Ignore the labels, look at the increased lift and duration and area under the curve.

        Attachment 59556