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GT-R RaceROM Boost Control

GT-R RaceROM Boost Control

Mar 19, 2020

 

 

GT-R ProECU Tuning Guide RaceROM Supplement: Boost Control

 

Table of Contents

 

Starting with RaceROM Phase 5, OEM boost control is depreciated and we recommend tuners use our own simplified boost control and now has its own full set of dedicated maps. Upon adding a Phase 5 or later RRFF, this option is enabled by default, and comes pre-populated with a sensible stage 1 boost control setup. All OEM boost control maps, are now found under Boost Control->OEM category in the map tree.

 

 

 

Table of Contents

 

 

Ecutek Boost Control vs RaceROM Boost Controller

There may be some confusion between the features for boost control in recent RaceROM versions, despite the similar naming due to historic reasons the two RaceROM features have different functions.

Ecutek Boost Control

Ecutek Boost Control is the control strategy to set the boost target and control the wastegate solenoid such that the boost reaches and remains on target.

 

RaceROM Boost Controller

(abbreviated to RBC) is a feature used to limit the boost target using the cruise control switchgear. The maximum boost target is displayed on the boost gauge of the MFD. As can be determined from the boost target flow diagram the boost target can be below the value set by the RBC but it can never exceed it.

 

Absolute Boost

The single most important concept introduced with Phase 5 GTR is the use of Manifold Absolute Pressure (MAP) for all aspects of tuning the boost control. All boost target, boost limit and boost threshold values are all absolute values in Bar. Tuners will now find that all boost related maps and live data will give consistent readings regardless of altitude, and calculations will hold true in all circumstances.

RaceROM Boost Controller values still correspond to the stock to the gauge, so 1.5bar still equates to 1.5bar of relative boost at sea-level.

To make tuning as simple as we can we have added an atmospheric compensation that by default gives a consistent “boost” at all altitudes, but the result is that your MAP will drop as a result, and power will be reduced at altitude if using the default Boost Target Atmospheric Compensation map.

To ensure that boost tuning is as simple and intuitive as possible, we have corrected the Nissan boost gauge display to show true manifold gauge pressure that will always correlate with the current atmospheric and absolute manifold pressure. Without this correction, your Nissan GTR boost display has been lying to you, displaying instead manifold absolute pressure – 1 resulting in strange behaviour at altitude. It has also been inconsistent with the actual boost level as measured by an independent gauge, such as the boost input on a dyno. This correction can optionally be disabled.

 

Boost Target Calculation

The boost target is obtained following the below flowchart. You will see that the RRBC limit is imposed both before and after custom maps processing, this ensures that custom maps cannot raise the limit beyond the limit set from the RRBC.

The RRBC is a final limit to any boost target, any boost target higher than the RRBC limit will be capped to the RRBC limit.

 

 

Enable Special Features (Boost Control Related)

 

Enable EcuTek Boost Control

Overall enable for the RaceROM boost control strategy used instead of the OEM turbine flow based strategy. Enabled by default and highly recommended.

 

Display corrected boost pressure

By default, the boost gauge shows (absolute pressure – standard atmospheric pressure) which means at altitude with the engine not running it will report a negative number. This options corrects the boost gauge to show a true relative pressure of (manifold absolute pressure – atmospheric pressure)

 

Enable RaceROM Boost Controller

Overall enable for the RBC, enabled by default. If turned off the cruise switchgear will do nothing RBC related.

 

RBC – Same value in all modes

Forces the RBC setpoint to be maintained even when switching MapSiwtch Mode. There is a limitation of this that ALL modes will have a maximum setpoint corresponding to the lowest of the four values in Boost Controller Maximum.

 

Use RBC as Custom Map input only

The RBC can be an excellent tool for interacting with Custom Maps. This option allows a value to be set using the cruise control switches, displayed on the boost gauge, but the value is not used as a limit to boost target. It is however available to use as a custom map, and used for example to adjust traction control implemented using Custom Maps.

 

Enable Upshift Spike Prevention

Overall enable for the USP strategy.

 

 

 

Map List

Live Data

  • Boost Bank1/Boost Bank2 – Absolute pressure in bar, measured by the two boost sensors

  • RBC Maximum Desired Boost – Relative boost max target, matches number format on gauge

  • Boost Target – Absolute pressure target in bar, measured by the intake manifold pressure sensor

  • Boost Error – Difference between MAP and Boost Target, positive numbers are over boost

  • Manifold Gauge Pressure – “Boost” pressure measure in bar above the current atmospheric pressure

  • Manifold Absolute Pressure – Absolute pressure in bar, measured by the intake manifold pressure sensor

  • Wastegate Duty – The duty cycle applied to the wastegate solenoid (Same as Final Duty)

  • WG Duty Base – Output from Wastegate Duty Base maps

  • WG Duty Adder – Correction resulting from Gear/IAT multiplier step

  • WG Duty Integral – WG duty added by Integral correction of EcuTek boost control strategy

  • WG Duty Proportional – WG duty added by Proportional correction of EcuTek boost control strategy

 

Boost Limit Fuel Cut

The manifold absolute pressure needs to exceed this limit, measured in Bar (relative) by the manifold pressure sensor, for a time that exceeds Boost Limit Fuel Cut Delay, to trigger a fuel cut as an overboost safety measure.