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Featured Hondata R&D finds limit of Civic CVT

Discussion in 'Engine / Exhaust / Transmission / Tuning' started by Hondata, Mar 23, 2017.



  1. Hondata

    Hondata Hondata Elite Sponsor

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    Scored belt (below) at maximum torque.

    [​IMG]

    Belt condition (below) after 6 hours of circuit racing at Miller Utah with Hondata 6 PSI reflash. As new!

    CVT drive belt after Miller 6 hour.jpg

    How CVTs work:



    For reference, here is our dyno chart from the CVT + 6 PSI tune. Our dyno is a little optimistic so our 220 lb-ft Dynapack torque is equivalent to around 200-205 lb-ft Dynojet torque at the wheels. Thats about a 15% increase over stock.

    [​IMG]
     
    Last edited: Mar 28, 2017
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  2. dc2turbo Senior Member

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    At what psi did you notice that it started to slip?
     
  3. Design Senior Member

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    Excellent readout. A must-read for CVT owners considering a custom tune.

    @Administrator - Recommend this be a sticky for a few months until the community can catch up.
     
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  4. Design Senior Member

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    I would think RPM (of the belt) might also play a factor here.
     
  5. dc2turbo Senior Member

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    it would be around 2800-3200 when peak tq comes in
     
  6. Design Senior Member

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    Can that be adjusted in the tune (yet)?
     
  7. dc2turbo Senior Member

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    you can adjust the boost by the rpm. So you could just add more boost after the peak tq to even out the TQ curve
     
    Last edited: Mar 23, 2017
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  8. OP
    Hondata

    Hondata Hondata Elite Sponsor

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    CVTs and automatic transmissions have a torque converter, which "slips" under varying circumstances. The same level of boost gives different levels of torque at different RPMs. So, we can't accurately specify PSI. Variables in this include transmission fluid temperature. The higher the transmission fluid temperature, the poorer the oil's lubrication and protection characteristics.
     
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  9. Design Senior Member

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    Saw your edit... my thoughts as well. On the MS3, we saw a similar problem. But the weakest link was the rods. Extending boost to the upper RPM range reduced that stress (at the expense of the factory turbo).

    @Hondata - Other thoughts on this issue? (Edit: NM, saw your post above).
     
  10. 360glitch

    360glitch Senior Member

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    So was a specific limit actually found? Was hoping for an estimated level of torque that the CVT could handle. Not really an issue for me, I am a 6MT guy but was curious.
     
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  11. OP
    Hondata

    Hondata Hondata Elite Sponsor

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    The data you are looking for would require an engine and transmission dyno. It would also require full control of the separate CVT computer. Honda Japan will have this information. A brief over-torque spike causing momentary slip is all that is needed to start the scoring on the belt. Once started, the CVT would transmit less and less torque as the scoring increased.
     
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  12. ichii

    ichii Senior Member

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    So would running it at the +6psi safe? Not issue with scoring the belt?
     
  13. dc2turbo Senior Member

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    at the end of the video, it states its safe to run
     
  14. HondaPro

    HondaPro Senior Member

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    So would it be safe to say you could achieve higher torque levels safely with a manual? And how much more?
     
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  15. PandaXpress

    PandaXpress Senior Member

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    Funny you ask questions like this when you "Pro" in your name
     
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