No Range device for C8
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,949
Likes: 12,362
From: NE South Carolina
Jerry,
The microslip feature is documented in the "MidEngine Revolution" book on page 182. It says " The new dual-clutch transmission, however, has less inherent capability [ than a torque converter to mask the engine vibration [that results when switching between four and eight-cylinder operation] which is why cylinder deactivation technology has so rarely been used on a car with a dual-clutch transmission. The C8 engineers were able to marry these two technologies [referring to torque converter capability to absorb the vibration] in the new Corvette, however, by putting some micro-slip into the clutch control of the DCT." In addition to that there is also a "pendulum damper" documented in several articles about the TREMEC transmission as follows:"Connecting the LT2 engine’s crankshaft to the TR-9080’s clutch basket is the responsibility of a flywheel carrying the starter ring gear and a centrifugal pendulum damper that’s needed to quell torsional vibrations erupting during the engine’s migration between V4 and V8 firing modes (a fuel efficiency improver)."
I am curious about your explanation for the v4 duty cycle. Where is that documented? While it makes sense that might be to compensate for leak-down of the captured spent charge (which is necessary for the "spring effect" they cite", I have never see that written anywhere. If that is the only reason, it seems like it would only need to open and shut for 1 cycle to recapture a charge, rather than 1 minute. I previously speculated (but its conjecture and no proof) that it was related to making sure the the engine block was evenly heated. I am also surprised that the captured, spent charge would actually last for 10 minutes.
The microslip feature is documented in the "MidEngine Revolution" book on page 182. It says " The new dual-clutch transmission, however, has less inherent capability [ than a torque converter to mask the engine vibration [that results when switching between four and eight-cylinder operation] which is why cylinder deactivation technology has so rarely been used on a car with a dual-clutch transmission. The C8 engineers were able to marry these two technologies [referring to torque converter capability to absorb the vibration] in the new Corvette, however, by putting some micro-slip into the clutch control of the DCT." In addition to that there is also a "pendulum damper" documented in several articles about the TREMEC transmission as follows:"Connecting the LT2 engine’s crankshaft to the TR-9080’s clutch basket is the responsibility of a flywheel carrying the starter ring gear and a centrifugal pendulum damper that’s needed to quell torsional vibrations erupting during the engine’s migration between V4 and V8 firing modes (a fuel efficiency improver)."
I am curious about your explanation for the v4 duty cycle. Where is that documented? While it makes sense that might be to compensate for leak-down of the captured spent charge (which is necessary for the "spring effect" they cite", I have never see that written anywhere. If that is the only reason, it seems like it would only need to open and shut for 1 cycle to recapture a charge, rather than 1 minute. I previously speculated (but its conjecture and no proof) that it was related to making sure the the engine block was evenly heated. I am also surprised that the captured, spent charge would actually last for 10 minutes.
Don't know that I have seen it stated by GM that is the only reason for switching back max every 10 minutes. I'm sure it losses some pressure in 10 minutes and also wonder why it has to remain off of a minute.
