Here's What Launch Efficiency Looks Like on a DEAD HOOK Graph- One of the simple things you can do when looking at a dead hook graph is to grab something straight and apply it to the screen, just a simple straight edge aligned with the upper section of the 1st gear engine rpm trace. I usually just grab an envelope and apply its edge to my computer screen...
If you apply that straight line to most graphs where the climb to the shift point is dead hooked, it will likely cross the vertical "O" line somewhere between zero rpm and 50% of launch rpm. On this graph where the car is set off at 7174rpm, that means the line will likely cross the vertical "O" line somewhere between zero and 3587rpm. If it crosses around or below zero, launch efficiency was poor. On the other hand if it crosses at about 3587rpm, that's about as good as it gets. Notice this straight line hits the vertical "O" line at about 2837rpm. That's pretty good, about 79% of its 3587 ballpark potential, but there's still room for improvement.
G-meter output is affected by pitch rotation, which basically means a 6k/1.75g launch with a big wheelie could actually be slower than a 5.5k/1.45g launch with a smaller wheelie. You will be able to compare runs with more accuracy if you first zero the runs to the first movement of the g-meter, then overlay the runs to compare the differences in both Erpm and DSrpm traces.
Most important for clutch tuning is the angle/shape of the Erpm trace as it is falling, as this is the ONLY part of the trace that is basically controlled by the clutch when the engine is at WOT. This is where you will be able to see area added "under the curve" to the rpm trace after the launch and after shifts, which are generally indicators of increases to power production which were made possible by adding/controlling clutch slip.
To verify overall gains from clutch tuning, compare the time it took from first movement of the G-meter to a selected DSrpm just before the finish line. These are points in the run where wheel spin is least likely, which in turn means they are points more likely to be accurate indicators of vehicle speed (this assumes of course that you are concentrating on clutch tuning, with no changes to gearing/tire size/air pressure). Basically you are looking for the quickest time overall from first movement of the G-meter, to a selected DSrpm just before the stripe.
You can also compare clutch performance during individual shifts on different runs by selecting a DSrpm just before that shift, as well as a DSrpm just before the next shift, then comparing the times between those two points.
If you plan to shift clutchless, adding even more delay has the diminishing affect of softening shift harshness. Some prefer to take it a step further and combine that added delay with an adjustable base pressure plate (without any added centrifugal assist). It basically gives them a direct way to adjust the clutch's breakaway torque, which affects the harshness of a clutchless shift. Choosing a non-adjustable PP can also get you there and will generally cost less money, but you will probably need to add some shims under the PP to get the wheelspeed spikes after those clutchless shifts under control.
Chapter 01- The Basics of Inertia Management
Chapter 02- Calculating Inertia's Effect on Input Shaft Torque
Chapter 03- Clutch Slip After the Shifts... Good or Bad?
Chapter 04- Heavier Cars LESS Likely To Break Transmissions?
Chapter 05- Understanding The ClutchTamer
Chapter 06- Understanding The Hitmaster
Chapter 07- The Basics of Analyzing Dragstrip Data
Chapter 08- Flywheel Weight- Heavy or Light?
Chapter 09- Choosing a Proper Clutch & Pressure Plate
Chapter 10- The Importance of a Clutch Pedal Stop
Chapter 11- What's the Best Launch RPM?
Chapter 12- Do You Need a 2-Step Rev Limiter?
Chapter 13- Traction Problems- Adjust Shocks, Chassis, or Clutch?
Chapter 14- Are "Clutchless" Shifts Right For You?
Chapter 15- Traction Control- Yes or No?
Chapter 16- Apply ClutchTamer Tech to an Adjustable Clutch?
CHANGING THE GAME ON LAUNCHING YOUR STICK SHIFT CAR!!!