Launch Control: Tuning
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Tuning
03.49
| 00:00 | The launch control function works by introducing a secondary rev limmit when the launch control system is active. |
| 00:07 | In most instances, we want to use an ignition cut for the RPM limit and this is particularly important if you want to combine an ignition retard to help build boost with a large turbo charger. |
| 00:19 | An ignition cut rev limit will cut spark to random cylinders to control engine speed. |
| 00:25 | I find it very effective although on some engines it can be quite aggressive depending on your limit settings. |
| 00:32 | The actual launch RPM is going to depend on numerous factors including the power the car makes, the usable power band of the engine, how much traction the car has, and also the condition of the track. |
| 00:46 | The right settings for a particular car can only be found by testing and logging to see what gives the best results. |
| 00:54 | In general, if I have no prior knowledge of a particular vehicle I'll start with a launch RPM limit of approxiamtely 5,000 RPM and test to see how well the car launches. |
| 01:06 | This sort of launch RPM is a pretty good starting point unless you have an engine fitted with a very large turbo. |
| 01:13 | In this case, you may need to use 7,000 RPM or even higher in order to create enough usable boost to get the car to launch. |
| 01:23 | When testing the launch control, you want to perform some test launches on the race track or a closed road and see how the car launches. |
| 01:32 | This can be hard on your drive train so you need to make sure the gear box and axles are up to the task first. |
| 01:39 | On that note, when we are testing to find the correct launch RPM it's always preferable to start with too much RPM rather than not enough. |
| 01:48 | If the RPM is too high, this results in wheel spin which is preferable to the car bogging down as this can place extra stress on the drive train components. |
| 01:59 | Even a moderately experienced driver will be able to tell when the car is launching well. |
| 02:04 | However, sit of the pants isn't always that accurate so I like to back this up with data logging. |
| 02:11 | If you can log 0 to 50, or 0 to 100 kilometer an hour tests, you'll be able to compare different launch RPMs to find which works best for you. |
| 02:22 | The aim is always to provide enough engine power that when the clutch is released there is sufficient power available to create a mild amount of wheel spin. |
| 02:32 | This is essential from a standing start since if we don't achieve some wheel spin initially the engine RPM will be dragged down and the car will bog hindering your launch, as well as putting a large amount of stress on the clutch and drive train. |
| 02:47 | Conversely, too much engine power will result in excessive wheel spin which may be slightly kinder on your drive train but doesn't do much for your acceleration. |
| 02:57 | The best compromise can only be found from testing. |
| 03:01 | It can also be beneficial to fit a multiposition switch or potentiometer to allow the launch RPM to be quickly altered from the driver's seat. |
| 03:11 | This can be useful if track conditions are changing quickly and a small change to the launch RPM is required without the need to access a laptop. |
| 03:21 | Remember when you're using this sort of launch control, that once the launch system has been disabled the ECU will not have any way of controlling engine power. |
| 03:30 | Hence, in a powerful car you may still need to modulate the throttle once the car is initially moving. |
| 03:37 | The more complex methods we'll look at later can achieve this sort of control, but for a basic system like this the driver still needs to do some work. |
