Data taken on this page was taken from a 2005 FSAE car using a 1991 Honda CBR600. We recommend 100psi line pressure for quick cylinder response/cylinder longevity reasons. When we get more data, we will be sure to update the website as soon as we can. Click on the graphics on the bottom of the page for a larger image as we will discuss the data each image represents.

Shifter Travel Chart

• It takes about 10ms for the actuator to start moving once the solenoid is activated
• Shifts in lower gears take longer, most likely due to the increased RPM drop for shift dogs to align
• We believe the motion recorded in the flat portion of the curve in first gear is due to deflection of the entire shift system as pressure builds while the actuator and string pot "catch up"
• In high gear, the speed of the actuator is nearly constant throughout the stroke. The high gear shifts had fuel cut-off times close to 30ms. There didn't seem to be any significant performance advantage when delaying the engine-kill to build up actuator pressure when "no-lift" shifting the car. This would likely lead to higher forces and increased wear to transmission components as the shift dogs try to engage as the RPM drops for lower gear changes.

Voltage Plots and Data System

• The middle plot shows five shifts in sequence. The system had a timing circuit which engaged the upshift actuator solenoid for 300ms. The plot does indicate some gear-jumping issues inherent from either an excessively worn gearbox or ECU hiccups. Because we hold the actuator open for so long, however, you see that the gear stays engaged.
  • The green line indicates the travel of the cylinder.
  • The red line indicates voltage to the upshift actuator circuit.
  • The blue line shows an inverse plot of the voltage supplied to the fuel injectors, making it easier to see when we cut power to the injectors. We do this by using a limit switch on the actuator.
• The "no-lift" system in this application used a 30-Amp relay with a normally closed circuit. The relay actuating coil is energized when the upshift solenoid is activated, then deactivated when the limit switch senses that the actuator has ended its travel.
• Shift times for this system are determined by the amount of time the fuel injectors do not have voltage supplied (typically 50-60ms in first gear decreasing to 30-40ms in fourth gear). Anytime voltage is supplied to the fuel injectors, we assume the engine is delivering power to the drivetrain and in-gear.
• Times for the mechanical relay to drop the injector voltage was consistently around 5ms.
• This mechanical relay circuit should have no problems passing the SCCA "No electronics" rule.