snip

  I am running the calcs for my programming and I have a question- My calcs
  are showing that 550 injectors may not be sufficient- here is what I came
  up with so far- correct me if I got it wrong-

  Our effective displacement is 1.3 liters per rotor- 2.6 total per
  revolution.
  Mass/ Density of air at 20 deg C at 1 ATM is 1.204 kg/M3

  I used 14.7:1 standard ratio of fuel/air for starters- these numbers tell
  me that at 100% VE  I will go through 23.475 kg/min of air.
  That equates to 1596 gm of fuel/min at 7500 rpm. I have not figured in the
  increased air from the 8psi boost that I am planning.

  The stock 550 injectors are shown to be capable of 395.6 grams// min and I
  am going to run 4. This equates to 1582.4 grams /min from all 4 injectors
  maxed out. My math says that without a turbo but at 100% VE these are not
  enough.

  1. Do I have the displacement wrong?
  2. Are any turbo guys having issues with lean mixtures at higher boost?
  3. Do I need bigger injectors or an additional pair of injectors?

  Kevin Alderman

  It always helps to have more injectors as you get a more precise setting
  with 8 bit
  tables and a wider dynamic range. That is why the stock RX8 engine has 3
  per rotor.

  Paul Lamar



  Kevin,

 I think that your volume calculation of air per minute is 4 times too high
 considering one rotor.

 The chamber displacement per rotor is 650 cc, and one chamber is displaced
 once per rotation.
 Cals: 0.65L * 7500 rpm/min /1000 *1.204 kg/ m^3 = 5.87 kg of air throughput
 per 7500 rpm per rotor at 100 VE.
 For two rotors the total fuel is to be based on twice that.

 Rolf

 5.87 Kg times 2.2 pounds per rotor is 12.9 pounds per minute.

 A p-port VE is 120% as well. It is more like 30 pounds per minute for a
 two rotor.


 Paul Lamar


OK, I think my calcs were about twice as much displacement as is actual. I
keep seeing the 1.3 liter being compared to 2.6 liters because of the power
cycle resembling a two stroke, so I used the 2.6 in the calcs. My numbers
above were total for the engine, meaning for both rotors. So, if my
displacement numbers are doubled, then the 550 injectors should be
sufficient. That is why my numbers didn't make sense.

Now if I can work out the issue of the advance.

Kevin Alderman

1.3 liter piston eater:) It is very misleading. We have spent hours and hours over
the past 15 years discussing this. The fact of the matter is: a one rotor rotary
pumps as much air in one rev as a one cylinder piston engine does in 2 revs. That is
where the 2.6 L comes in. It is equivalent to a 2.6 liter piston engine. Don't even
think about 1.3 L. But if you must here is what the God of the rotary says.


Paul Lamar
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