2.66 low gear vs close ratio
Here's something that can throw a kink in gear calculations when it comes to predicting rpm drops at the track. Here is a graph from a NMRA factory stock racer using one of my ClutchTamers to control clutch slip.
...the dark blue line is the actual trace from the run.
...the added lite blue line represents calculated rpm drops based on the ratios in the transmission.
As you can see, straight gear calculations do not account for clutch slip. On the above 1/2 gearchange, actual rpm drop was a little over 1000rpm less than the calculation predicted. On the 2/3 shift, the difference was around 650rpm, 3/4 shift was around 375 less rpm drop than predicted. Of course if the clutch would have locked up quickly the drops would have been closer to the predictions, but it would have taken longer for the car to complete the run as the engine would have had to work it's way back up from a lower rpm after the shifts.
Quicker clutch lockup would not only result in a slower run, but the quick engagement would also pass along more abuse to your transmission/drivetrain.
Here's something that can throw a kink in gear calculations when it comes to predicting rpm drops at the track. Here is a graph from a NMRA factory stock racer using one of my ClutchTamers to control clutch slip.
...the dark blue line is the actual trace from the run.
...the added lite blue line represents calculated rpm drops based on the ratios in the transmission.
As you can see, straight gear calculations do not account for clutch slip. On the above 1/2 gearchange, actual rpm drop was a little over 1000rpm less than the calculation predicted. On the 2/3 shift, the difference was around 650rpm, 3/4 shift was around 375 less rpm drop than predicted. Of course if the clutch would have locked up quickly the drops would have been closer to the predictions, but it would have taken longer for the car to complete the run as the engine would have had to work it's way back up from a lower rpm after the shifts.
Quicker clutch lockup would not only result in a slower run, but the quick engagement would also pass along more abuse to your transmission/drivetrain.
