How do you pull timing for boost on an LS tune?

• Start safe: LSX Magazine's approach is to pull timing in every table area that might see boost, then add it back carefully on the dyno.
• Why less timing under boost: Corky Bell (Maximum Boost) explains that the denser boosted mixture burns faster, so it needs less advance. The same idea lets you keep more advance at low-speed cruise.
• Map it by load, not a blanket retard: Bell notes that a simple retard that increases with boost costs mid-range torque, because timing ends up set for maximum boost everywhere. A timing table indexed by manifold pressure lets each boost level have its own value.
• Where the tables live: HP Tuners' 2.5-bar custom operating system adds boost-region VE and boost-enrichment tables in 5 kPa steps above 105 kPa. It's speed-density only.
• Turbos specifically: a turbo can make boost at part throttle and low rpm before normal power enrichment starts, so boost fueling and timing must cover those areas too (LSX Magazine).

See fuel, E85 & boost.

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