Peripheral Port Comparison

Here is a look at auto versus manual actuation of the peripheral port.  Unlike using a carburetor, fuel injection allows us to deliver the correct amount of fuel even during periods of high flow reversion that would otherwise cause a carburetor to supply too much fuel.  We have found in other applications that the peripheral port can be opened as soon as the engine has ANY load, that is, anytime the engine is not idling.

Here you can graphically compare an auto actuation of the peripheral port with a manual actuation.  The auto actuation is a best case scenario with elevated torque values as the rotor has yet to thermo saturate.  This graph is elevated by one to two ft-lbs in the 3500 to 6000 rpm range.  This thermo saturation phenomenon points out the need for a thermal barrier on the rotor face to prevent inlet charge heating.  Slowing thermal transfer from the combustion chamber to the incoming charge will improve torque by elevating charge density and keeping the heat in the combustion chamber where it can do more work.  This should also improve bearing life.

Tabular data for certain portions of the above plots can be found at  Auto Open Table Data and Manual Open Table Data.  Lastly, you can find an overlay comparison of the tabular data here.

I believe the best approach would be to manually open the peripheral port by attaching it to the primary throttle body shaft.  Past experience has shown that the peripheral port can start opening at ten degrees of primary throttle opening and completely open by twenty degrees.  The key for proper fueling is to ensure the actuation relationship between the peripheral port and primary throttle is consistent across production.  Any change in this relationship will cause a lean or rich condition during the transition.


Auto Actuation

Manual Actuation