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Air mass calculations for forced induction applications

EFI Tuning Fundamentals

Relevant Module: How the ECU Works > The Speed Density Principle

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Discussion and questions related to the course EFI Tuning Fundamentals

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I have just completed the fundamentals of EFI course. I am now moving on to the understanding AFR Course as Ben recommended at the end of this course. I bought this course so I could learn how to tune my EVO 9. So, as I perform these calculations presented in this course, I find that those calculations are based on NA applications. If I am going to do all the math prior to tuning so I have all my ducks in order, I don't know that I should be tuning a forced induction engine with NA calculation. What are the calculations necessary to account for the theoretical additional air mass entering the engine? When exactly would I calculate for the additional boost added by the turbo since there is the lag?

Also things to note: I intend on installing a Link g4x plug and play so I will be starting from scratch. I know that you have a link tutorial as part of the curriculum that I purchased. I have watched that, but it wasn't helpful. My take away from the course just showed me how I can change the layout.

Jason

Why wouldn't the calculations be the same? The only thing that changes is the pressure and temperature of the air.

I was able to recalculate my thought process on the matter and was able to build quite an extensive excel worksheet putting all of the speed Density calculations to work. I was having trouble figuring out how to make the calculations with out accounting for those variations, and then i quit fighting myself and realized that i need to make a table that reflects different volumes at different RPM's just as they would be structured in the ECU. If I would of just watched the Understanding AFR section, I would of made the connection before posting this.

Jason

Jason,

With the G4x you can use the modeled airflow mode and simply VE tune.

This accounts for manifold pressure change as part of the model, so no outside effort is required.

Im still fairly new to this platform. I haven't navigated to that yet or know what that is. I started the car on the base tune that the program comes with and I was having a hell of a time understanding what I needed to do next. I posted somewhere else in regard to this as well, but the MGP is not something I understand enough to adjust properly, so I am learning about how adjustments there effect the tune. Any literature or webinars you can direct me to that might help me get on the right track?

Absolutely Jason. HPA's Practical Standalone course has all sorts of info on this and more, including specific worked examples with Link ECUs:

https://www.hpacademy.com/courses/practical-standalone-tuning/

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