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Start up tune.

General Tuning Discussion

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Hello, I am in the process of swapping in a 408 Ls into an 86 c10. I will be using a pcm from a 5.3 with hp tuners. I’m wondering what I should use for start up in the ve table. I don’t want to hurt my fresh engine with a bad tune before I get in the ball park. Also, I am wondering who has quality injectors with reliable data. This is my first real tuning experience. All help will be appreciated. Thanks, David

Hello David,

Ordinarily we would assume the VE based on the engine architecture with peak VE being around peak torque but in the case of GM and HP tuners this is not possible as the VE table is just a scalar with number in the orders of thousands. Depending on the year of the PCM it could run a virtual VE table that will be populated based on the data you input but you can do some targeted research in this area, there will be information more specific to your application

As a base though you pull the original map off the 5.3 ECU and calculate roughly the amount you'll need to trim the fuelling by so that's around 26% based on the displacement alone. Inversely fuelling can be back calculated by calculating the airflow requirements for a given bhp with some assumptions for actual VE which will be in the order of 85-95% for a 2 valve head depending on the state of tune. As a start map you only need to calculate a few operation points then interpolate from there to populate the rest of the map. offers some really good base knowledge for engine calculations and its much easier to digest than the Haywood type text books.

regarding injectors; I've personally only really used Bosch motorsport injectors direct from Bosch motorsport or batched and categorised my own from OEM injectors on a custom built test rig - this is essentially what some performance injector companies do with OEM injectors from Bosch/Siemens/Denso etc and re-brand them. If you're wanting something off the shelf and easy try looking at ASNU, RC, DeatschWerks and Injector Dynamics. - - -