What Are The Custom OS's & Their Differences?

Modified on Thu, 26 Oct 2023 at 08:53 AM

1 Bar MAF custom OS

Available on most 99+ LS1 based PCMs.

Adds RTT to the stock calibration.

1 Bar SD custom OS

Available on most 99+ LS1 based PCMs.

Adds a VE Multiplier vs. TPS vs. RPM table
secondary VE table not used (if applicable)
Speed Density Mode Only
Dual (High and Low Octane) Spark table support
Adds RTT (most calibrations).

2 Bar SD custom OS

Available on most 97-07+ LS1 based PCMs.

2 bar MAP sensor support (calibration capability for GM 0-5V linear MAP sensors)
Extended Main VE table to 210 kPa (2 bar)
Retains full 5 kPa resolution in non-boost regions (most calibrations)
5 kPa resolution in boost regions (most calibrations)
secondary VE table not used (if applicable)
New MAP referenced "Boost Enrich" table
New open-loop MAP threshold
Dual (High and Low Octane) Spark table support
Speed Density mode only
VCM Scanner histogram automatically recognizes and adjusts for 2 bar feature (if applicable)
New 2 bar MAP PID for VCM Scanner (if applicable)
Adds RTT (most calibrations)

3 bar SD custom OS

Available on most 99+ LS1 based PCMs.

3 bar MAP sensor support (calibration capability for GM 0-5V linear MAP sensors)
Extended Main VE table to 315 kPa (2 bar)
Retains full 5 kPa resolution in non-boost regions (most calibrations)
5 kPa resolution in boost regions (most calibrations)
secondary VE table not used (if applicable)
New MAP referenced "Boost Enrich" table
New openloop MAP threshold
Dual (High and Low Octane) Spark table support
Speed Density mode only
VCM Scanner histogram automatically recognizes and adjusts for 2 bar feature (if applicable)
New 3 bar MAP PID for VCM Scanner (if applicable)
Adds RTT (most calibrations)

2.5 Bar MAP - Speed Density (LS2 V8 - E40 ECM)

This enhancement contains the following features:

2 bar or 2.5 bar MAP sensor support (calibration capability for GM 0-5V linear MAP sensors)
New Boost VE table from 105 kPa to 255 kPa (2.5 bar or 22.5 psi boost)
Retains stock VE table resolution in non-boost regions
better than 5 kPa resolution in boost regions (105 kPa - 255 kPa)
New MAP referenced "Boost Enrich" table in 5 kPa increments
New Boost Enrich MAP threshold
Speed Density mode only
Rescaled fan temperature axis 163-250F (73-121C), stock is 192-250F (89-121C)
VCM Scanner histogram for Boost VE table included in histogram library

2.5 Bar MAP - Speed Density (E38/E67 ECM)

This enhancement contains the following features:

2.5 bar (255 kPa) max MAP sensor support (calibration capability for GM 0-5V linear MAP sensors)
Rescaled High MAF table supports up to 15400 Hz with 300 Hz resolution, also supports airflow up to 1024 g/sec
New VE tables with 33 x 33 cell resolution each and configurable MAP and RPM axes (choose your own resolution)
Charge Temperature based VE multiplier table, configurable axis
TPS based VE multiplier table, 33 x 17 cells with configurable TPS and RPM axes
MAP referenced "Boost Enrich" table
Boost Enrich MAP threshold and hysteresis value
Both MAF and Speed Density mode supported
Boost based fuel cut, selectable MAP threshold cuts fuel to all cylinders when exceeded
Rescaled fan temperature axis 163-250F (73-121C), stock is 192-250F (89-121C)

Would there be any advantage of using a 2 or 3 bar Custom OS on a Naturally Aspirated Engine?

In most cases, no. Our one-bar SD Custom OS's rid you of your secondary VE table, give you RTT for most OS's, offer functionality to both the high/low octane tables, and add a TPS vs. RPM multiplier. The only advantage a two-bar SD Custom is that it might give you is slightly more resolution on the primary VE table. However, in most cases this isn't worth the extra time and effort.

 

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