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Old 10-17-2020, 10:40 AM   #3
Norm Peterson
Scooby Specialist
 
Member#: 498642
Join Date: Mar 2019
Chapter/Region: Tri-State
Location: our wrx IS the family sedan
Vehicle:
'19 WRX Ltd 6M dgm
'08 Mustang GT (the toy)

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Quote:
Originally Posted by DieselDorf View Post
My opinion on why CVTs are underrated I think most will agree?
Any chance you could provide a short summary in text in a follow-on post?

I'm interested to see if what you've concluded lines up with what I have. Your link actually does work for me, but I find trying to learn much from a video at the videographer's pace to be far more difficult than reading the same material at my own pace. That it's been over half a century since I last sat in a lecture hall, and that my hearing isn't what it was back then, probably has something to do with it.

I do understand that - at least in theory - a CVT can keep the engine working at an optimum rpm, or at least within a much tighter rpm spread around that rpm. Ideally, holding rpms at the power peak should translate to best acceleration, at least on average. More on that later.

My guesses for why a CVT doesn't do much as far as enthusiast appeal is concerned are that (1) a CVT is even less involving than a conventional multispeed automatic, (2) it's inherent for a CVT to put the engine rpms out of step with the car's acceleration, and (3) as a function of (2) that it's likely to sound like something is slipping even when it isn't. With a manual transmission, slippage is a bad thing beyond the minimal amount necessary to get underway without stalling or burning rubber. In a conventional automatic, it's apt to be shift flare (which is not a desirable condition either).

One catch about stronger average acceleration is that it's apt to not hold true when you dip into the throttle from a standing start. Under this condition, the drive pulley is at its smallest diameter where it's at its lowest torque capacity, so you end up with some (or a lot) of your low end torque managed away. Given that a majority of enthusiasts first see 0 - 60 and quarter mile ETs as indications of a car's basic "goodness", it's not hard to see where appreciation for the CVT takes a big hit.

One thing I don't have any real 'feel' for is how a CVT's overall efficiency compares to that of a conventional automatic. I suspect it could be higher, though a CVT still has a fluid pump that has to be running continuously at enough load to eliminate drive slippage.

Am I wrong?


Norm
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