My friend wants to build a 20b RX8

Discussion in 'OT Driven' started by art_VW_shark, Aug 13, 2007.

  1. art_VW_shark

    art_VW_shark OT Supporter

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    The kid is dillusional, he's doing armed services and then college (technion, one of the best tech schools in the world) and thinks he'll be able to at any time afford this project. :hsugh: how hard are 20bs to come by?
     
  2. Tom93R1

    Tom93R1 Member

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    easy to find, but about $10k for a used one and to get it rebuilt.
     
  3. Rich

    Rich New Member

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    I had a friend that thought he could drop an LS1 into an RX7 in a weekend and daily it. I told him he was a fucking idiot but he kept arguing.
     
  4. E-dub

    E-dub New Member

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    My bro did one in 3 days. But he builds cars in his sleep.

    20b is not cheap. No one has really done swaps in RX8's except for the big $$$ shops in Japan. Sounds like this is a good way to kill an RX8. Let me know when he wants to dump the shell for cheap, I need an RX8 roller for an LS2.
     
  5. deusexaethera

    deusexaethera OT Supporter

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    That's a great idea! Replace a new, good engine with an old, busted one!

    There's a reason Mazda doesn't still put the 20b in their RX's. They get about 1 mile per gallon and they have a nasty tendency to explode.
     
  6. art_VW_shark

    art_VW_shark OT Supporter

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    ...the 20b was never a production motor bub. and when you say old and busted, new apex seals and its good to go amirite
     
  7. GTSlow

    GTSlow New Member

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    yes it was. it was in the cosmo (japan only).
     
  8. dew

    dew Banned

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    here we go again ...
     
  9. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    It'll never happen anyway.
     
  10. Captain Amazing

    Captain Amazing OT Supporter

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    Its been done. There are a few on the rx8club.com
     
  11. huntz0r

    huntz0r New Member

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    Supremely dumb idea.
     
  12. art_VW_shark

    art_VW_shark OT Supporter

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    what years?
     
  13. Dysfnctnl85

    Dysfnctnl85 IT/Apple/Rotary/(D)SLR Crew

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  14. Dysfnctnl85

    Dysfnctnl85 IT/Apple/Rotary/(D)SLR Crew

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    It should be a given that any used 20b you buy will have one busted housing. Housings are not cheap. $10K sounds about right for a PROPER* 20b.

    *Rebuilt using quality materials and through a reputable individual or shop; capable of handling your hp goal;
     
  15. The Ripper

    The Ripper New Member

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    20b is an amazing engine but for the money he spends hes better off boosting the renisis. didnt the ptp kit pull some good times?
     
  16. deusexaethera

    deusexaethera OT Supporter

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    I'm feeling kinda dumb now. Which one was the one in the third-gen RX-7? 13b?

    EDIT: You know, I bet there'd be a market for rebuilding Renesis engines with custom eccentrics and third rotors. No reason why it wouldn't work, you'd just have to set up Rotor 3 to draw from Rotor 1's spark timing.
     
  17. Vicious-S

    Vicious-S New Member

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  18. Dysfnctnl85

    Dysfnctnl85 IT/Apple/Rotary/(D)SLR Crew

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    13b-REW was in the FD.

    Custom eccentrics = super $$$$. Not to mention RENESIS housings and rotors...
     
  19. deusexaethera

    deusexaethera OT Supporter

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    Do the rotors and housings really cost that much? It must be the special surface treatments.
     
  20. Tom93R1

    Tom93R1 Member

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    If only it were so easy to build 3 rotors by just stacking on another plate and housing.

    To run rotor 3 off the rotor 1 spark timing you would have 2 rotors running 180* out from the third rotor. This would require an enormous counter balance and even then the power pulses would be horribly unbalanced. Basically no way around an aftermarket computer. It needs to be run at 120* intervals.

    Due to port design incorporating different sized primary and secondary ports (not to mention the extra ports for 6-port motors) you would need to re-design that funky big 20b plate that has secondaries on one side and primaries on the other. Plus the extra e-shaft length requires an extra bearing in that plate. To top things off the machining of a custom eccentric shaft is no small feat.

    Without some super elite fabrication skills it would be extremely difficult to be able to make a 3-rotor renesis motor. There is nowhere enough benefit that anybody would be willing to pay what it would cost to develop instead of just getting the already available 20b. I am quite confident that it will never be done unless Mazda decides to make one themselves.


    I am sure its been done by more than just them, but Acosta Motorsports is the only 20b conversion on an RX8 I have seen. SpeedSource is working on one, maybe has it completed.
     
  21. S13Koop

    S13Koop OG Lurker

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    [​IMG]
    Friend of mine picked this up not long ago
    [​IMG]
    at an Austin Mazda dealership
    Funny you made this thread, I'm been doing a lot of research on 20b's the last few weeks (putting a rotary in my other 240)
    20B is pretty expensive new.
     
  22. deusexaethera

    deusexaethera OT Supporter

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    What's that wrapping around the exhaust side of the turbo?
     
  23. S13Koop

    S13Koop OG Lurker

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    Heat wrap/blanket
     
  24. deusexaethera

    deusexaethera OT Supporter

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    Riiiight...what brand is it?
     
  25. S13Koop

    S13Koop OG Lurker

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    [​IMG]
    :dunno:
    to be honest, I'm not really sure
    Are you looking for one?
     

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