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08 - TC Launch Control

General

Launch Control is a method of controlling the revs at the start. It is activated by the launch control button.  This allows full throttle to be used, and the revs are controlled by the traction control. This means you only have to balance one foot instead of two.  The system uses a secondary rev limit that removes itself automatically when the rear wheels are within a set percentage slip of the front wheels.

The Launch Control rev-limits can be programmed using two methods depending upon whether you have access to a laptop computer.

The Launch Control has two different rev-limits that can be set, WET and DRY.  The wet rev-limit only works when the switch is positioned in the WET position.  All other settings on the switch use the DRY launch.

 

Adjuster Program

The Launch control rev-limits can be programmed using the launch button supplied as part of the Traction Control Switch.  Follow the procedure below to program in Wet or Dry rev-limits.

 

  • Turn the vehicles ignition OFF.
  • Turn the adjuster to wet or dry settings depending upon which rev-limit you wish to program.
  • Turn the vehicles ignition ON and start the vehicle.
  • Press the launch button once.
  • Press the launch button again and hold down the launch button.
  • Rev the engine to the desired Launch rev-limit.
  • Release the launch button.
  • The rev-limit will be set.

 

NOTE - When using the launch button to calibrate, the soft cut is set when the button is released, and the hard cut 250 RPM higher.

e.g. –     To set the wet rev-limit to 4000 RPM.

                Start the car.

                Switch to wet settings.

Press the launch button twice and hold down on the second press.

                Rev to 3750 RPM.

                Release the button.

                The soft cut is now set to 3750 RPM and hard cut to 4000RPM.

Laptop Program

Run the software and enter the Launch Control tab.  Program the rev-limits as desired. See the software article for further information. 

Launch Procedure

Button Initiation – Stop the vehicle and press the launch button once leaving the adjuster selecting the desired percentage slip.

The car will then rev-limit between the programmed soft and hard cut limits.  The rev-limit and launch control strategy depends upon whether wet or dry settings have been selected with the adjuster.

After 2-3 seconds the car should be settled on the Launch Control Rev Limit.  If it is a turbo car the boost pressure should be gradually building up.

A common mistake is to bang the clutch in and instantly spin the wheels. The first 10 metres is the most critical phase, even a small amount of wheel spin at these low speeds is very high in percentage terms. The clutch should be slipped whilst not breaking traction, but not too much as to impede forward progress.

If you can't slip the clutch, then change it for one you can, you are losing out, here is why :-

The clutch can be used as torque converter.  The torque curve on a race engine is going to be biased towards higher rpm, at low rpm there will not be a surplus of torque over wheel spin.  Therefore the engine needs to rev before it can accelerate the vehicle at an effective rate. The clutch translates this high rpm into high torque.

On a low powered engine that cannot spin the wheels in first gear, the slipping clutch translates the stored momentum of the engine into torque to artificially boost the acceleration in the first few metres.

On a high-powered vehicle, the slipping clutch prevents the wheels from initially breaking traction, the most important factor in a good start.

If the car “bogs down” or has too much wheel spin adjust the rev-limits to program the perfect start.

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