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Staged tertiary injector


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I'm looking at setting up a link xtreme ECU on a Mazda RX8. This is a 2 rotor engine and stock has 3 injectors per rotor for 6 total. the second and third injectors do not operate until appropriate intake valves in the manifold have opened (secondary valve opens at approx 4k rpm and the tertiary opens at approx 6krpm).

Is it possible to set up staged tertiary injection (I can only see options for secondary injection) or would it be easier  just to run a larger secondary and drop the third injector.

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You can use aux injection control to give you effective tertiary control. However on the stock RX8 manifold the bigger issue is controlling the opening of the valves as they are not a not solenoid controlled I'm led to believe.


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  • 4 years later...
  • 2 months later...

Jumping in to follow this.... Mind you, It'll be a 4x ECU (or a 5 when they appear...)

Would it be best to use the Aux control for the "last" set of injectors to come in? or the "first"

The logic here is to use a really tiny (150-250CC Min Injectors) that have a really fine spray pattern that give a cloud spray pattern, not a Squirt. This pair sits in the Standard Centre plate injector holes and only need to run at lower RPM/airflow. More Important with Larger porting and Driving to the shops. 

Once you have some airspeed ( over 2500) you can cut to the injectors in the runners (Its more a quad runner intake issue) . Running the Small injectors on the centre plate and a Pair of whopping big 13G injectors above the throttle body on a dual throat gave really good around town fuel economy compared to using 550's. 

The main advantage here is you don't get fuel wetting and puddling in the intake when driving around, and you also don't smell of fuel when you get home. And you get a substantial fuel economy advantage.

Racing? Well....  As long as it shoots flames on overun.. do you really care?


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