Quote:
Originally Posted by RCZ
I think I remember hearing in the Nissan videos that the car uses throttle position, sensors in the shifter and speed and G sensors to calculate the optimal RPM. I think it just blips the throttle and gets it to a predetermined RPM (as a function of data from the sensors) rather than taking the weight of the flywheel into account. If I'm right, a lighter flywheel would mean even quicker rev matches. If you think about it from Nissan's point of view, its much easier to calculate the necessary RPM's and then just say "100% throttle until you reach that RPM, then hold and revise every millisecond using data from the sensors"
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Thread revival!
You're pretty much on the mark.
Here are the sensors that make it happen:
1- Clutch pedal sensor (the same one that allows you to start the car, ie. detect pedal is fully depressed)
2- Crank angle sensor (on the bell housing)
3- Neutral position sensor/gear lever position sensor
4- Input speed sensor (on the rear left hand side of the gearbox. Not far from the reverse sensor)
5- rear wheel speed sensors (on the diff). This one i'm not 100% sure about as #4 should suffice for smooth shifting.
1 tells the system to wake up
3 tells the system what gear you are currently in & what gear you are entering
4 tells the system how fast the (output i think) shaft in the gearbox is rotating. Automatic gearboxes use an input speed sensor for the same purpose - to enable smooth shifting.
2 is obvious - i tells the system what RPM the engine is rotating at and the system calculates the target engine speed based on the signal from #4 and #3.
Since the ECU can respond to throttle inputs that quickly, i'd assume if you swapped in a lightweight flywheel and lightweight underdrive pulley, the system would not overrev the engine. It will back off once the target RPM is reached.
PS. I'm not an expert.