Hondata R&D finds limit of Civic CVT

Hondata

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Scored belt (below) at maximum torque.

cvt-drive-belt-maximum-engine-torque-jpg.jpg


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.

17_civic_cvt_stock_87_oct_vs_91_octane_plus_6_psi.gif





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dc2turbo

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At what psi did you notice that it started to slip?
 
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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.
 

Design

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you can adjust the boost by the rpm. So could just add more boost after the peak tq to even out the TQ curve
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).
 

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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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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.
 

ichii

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

HondaPro

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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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