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Calculating Master Fuel Value on a Rotary Engine with Staged Injection


HaveYouSeenAWizardSleep

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Hey, wrapping up my FC RX-7 build, got it running on old crusty Turbo II injectors I had sitting around. I used the S6 Base Map to get it running with little altercations.

 

To my knowledge the S6 uses 550cc Injectors for the primaries and 850cc for the secondaries. I’m familiar with usually calculating my master fuel value with some basic algebra using:


Old Master Fuel Value / (New Injector Size / Old Injector Size) = New Master Fuel Value

 

I have now obtained Injector Dynamics ID1050X (1050cc Injectors @ ~40psi) for both the primaries and secondaries, I’m quite clueless as to how I’m going to calculate the new master fuel value based on my new injector size.

 

Any help and knowledge would be gladly appreciated, still learning. Thanks.

 

 

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10 minutes ago, Adamw said:

Our FD test car has the stock 550 primaries and 1600 something in the secondaries (roughly 2150cc total per rotor), so I would expect your 2 x 1050's to be in the same ballpark.  Master fuel around 12ms should do it.  

Ahh, I see so technically speaking the way it’s calculated is based on the “total cc” per rotor?

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Roughly if we forget about deadtime and all the other compensations, Injector PW is calculated as Master x fuel table x (MAP/100), this PW assumes a single injector.  The PW then gets divided up by the staging table & sec flow ratio and the appropriate proportion sent to each injector.

So an example, 10ms master, 80% fuel table, 200kpa MAP.  Total PW = 10 x 0.8 x 2.0 = 16ms.  In your case the sec flow ratio is 1:1 and your staging table will have 50% in it, so half that 16ms goes to primary(8ms) and half goes to secondary (8ms).

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