GT-R RaceROM Launch Control, Rolling Launch and BOTL
GT-R ProECU Tuning Guide RaceROM Supplement: RaceROM Launch Control, Rolling Launch and BOTL
This guide covers the RaceROM advanced Launch Control features. For information on the RaceROM Launch Control refer to GT-R Factory Launch Control
RaceROM Launch Control, Boost off the Line (BOTL), and Rolling Launch
The RaceROM Launch Control feature allows you to adjust the launch control RPM live. This can be used to provide a higher or lower power/torque output during launch to suit the driver’s requirements. In addition, you can specify a pre-launch manifold pressure target for each mapswitch mode. The ECU will dynamically retard and advance the ignition timing in order to achieve the target. Launch control has been updated for Phase 6 with additional control of ignition retard for BOTL and a throttle compensation for retard to prevent engine speed from dropping significantly as retard is increased to achieve boost for launch. Meanwhile Rolling Launch allows you to hold a steady vehicle speed while building boost to enable an abrupt acceleration forward.
Table of Contents
- 1 GT-R ProECU Tuning Guide RaceROM Supplement: RaceROM Launch Control, Rolling Launch and BOTL
- 2 Table of Contents
- 2.1 Method of Operation
- 2.2 RaceROM Rolling Launch
- 2.2.1 Rolling Launch Accel Rest Point
- 2.2.2 Rolling Launch Accel Threshold
- 2.2.3 Rolling Launch Antilag Timeout
- 2.2.4 Rolling Launch Enable
- 2.2.5 Rolling Launch Ignition Proportional
- 2.2.6 Rolling Launch Maximum Boost Target
- 2.2.7 Rolling Launch Target AFR
- 2.2.8 Rolling Launch Target Manifold Pressure
- 2.2.9 Rolling Launch Throttle Compensation
Method of Operation
The launch RPM is set in the Engine ECU and cannot be adjusted from the factory.
ECM ROM Series | ECM Launch Control RPM |
|---|---|
JF Series (LC1) | 4500rpm |
JW Series (LC3) | 3300rpm |
KB KJ 38 Series (LC4) | 4100 |
EcuTek have developed RRLC so the Launch RPM can be adjusted LIVE during the Launch Mode. This allows the driver to select the optimum launch RPM (and therefore engine power output) for the current conditions.
RRLC allows the driver to adjust the launch RPM by pressing the cruise control “res/accel” and “coast/set” buttons while the launch control system is active.
With launch control active, whilst fully depressing the accelerator pedal, press the “res/accel” button to raise the launch RPM. Press the “coast/set” button to lower the launch RPM. The default Launch Control RPM (set in the ECM ROM) will be used after ECU Programming, ECU Reset or disconnecting the battery.
If the RRLC is used to change the default LC RPM, then this new RRLC RPM is stored ready for the next launch (unless the ECU is programmed or ECU Reset etc).
Map List
Live Data Parameters
Dig: BOTL Active (True / False) – Flag showing if BOTL is active
Dig: Launch Control Active (True / False) – Flag showing if launch mode has been entered.
Launch BOTL Ignition Base (°) – BOTL Base ignition timing
Launch BOTL Igntion Proportional (°) BOTL proportional ignition correction
Launch RPM (RPM) – Current launch control target RPM including any overshoot
Launch RPM Base (RPM) – Current launch control RPM without any overshoot added.
Launch RPM Error – Difference between Actual and Launch RPM, positive is over target.
Launch Timer (s) – Time since launch mode became active
LC Flags
1 - BOTL Active
2 - Throttle Integral Active
4 - Launch Control active
8 - Post Launch
16 - Rolling Launch active
32 - Torque actual limit active
Note: These values are displayed as a sum e.g. 3 = 1 +2 = BOTL Active & Throttle Integral Active
BOTL Activation Delay
Launch Control must have been active for at least this delay for BOTL to become active, this is usually not important as the timer will have expired by the time the activation RPM has been achieved.
BOTL Activation RPM
The Boost Off The Line Strategy will be enabled when the Launch RPM Error exceeds the upper value and remain active until is drops below the lower value. The lower value to disable BOTL is deliberately low to ensure that BOTL doesn’t cycle on/off due to RPM fluctuations caused by the BOTL itself.
Raising the upper value to -100 RPM will disable the BOTL retard from activating until later and may be useful for large turbo cars. Increasing the upper value to more than -50 RPM may have undesirable results as the actual RPM approaches the target launch RPM slowly once close to the target.
BOTL AFR Target
Fixed target AFR while in launch control (LC) mode.
BOTL Fuel Compensation
This can be used to multiply the fuel quantity while in launch control to make broad corrections for errors in AFR.