Back story This has been on the back of my mind for a while. I once had a long-term rental (5 months) with a CVT transmission, and after a couple of days, I figured out the best way to drive it, and, once I got used to the engine sound not matching the vehicle speed in a certain gear, I started to appreciate the CVT a lot more. I could accelerate aggressively and still get excellent fuel mileage.
Premise With a manual or a conventional automatic, there is a linkage between the engine's crankshaft and the gears. Accelerating involves getting the engine to increase it's revolutions (RPMs), and through the linkage, the gears and wheels will increase their revolutions. When the engine revolutions are outside the desirable range (too high or too low), changing gears will provide a more suitable linkage, but again, accelerating involves getting the engine to increase it's revolutions. The engine is providing the power for the acceleration, gears are only converting the engine speed into wheel speed.
With a CVT, high throttle demand will have the engine rev to it's optimal powerband, and then the vehicle speeds up by having the CVT continuously change the ratio between the crankshaft and driveshaft. Since the engine remains at the same revolutions during the acceleration, it's the CVT that is providing the actual acceleration, not the increase in revolutions as with a conventional transmission.
The Question During hard acceleration with a CVT:
- is the CVT simply fighting an increase in the engine's revolutions by increasing the effective gear ratio, making a CVT an automatic with an infinite number of gears and better linkage?
- would the CVT changing the effective ratio more quickly make the vehicle accelerate faster, or would it simply bog down the engine with too much of a load?