George
       George (down under) asked about a leak down regulator by-pass. He is
       concerned about maintaining pressure in the fuel system after
       shutdown. I an not familiar with it so if you can give me an
       application reference, maybe I can comment on it.
       Pressure is maintained the fuel system after shutdown to allow a
       quick start during the next start up. If pressure is relieved at
       shutdown, the fuel in the top loading injectors will begin to
       vaporize as the engine temperature increases and could actually
       displace all of the liquid fuel in the injector. It would take a
       considerable amount of engine cranking to clear the vapor from the
       injectors.
       There are injectors called "bottom loading" where the fuel enters at
       the bottom of the injector instead of the top. Bottom loaders can
       clear the vapor much faster than top loading injectors.

       Joel


   Joel,
   My information suggests that the fuel pump provides sufficient
   pressure in seconds or even instantaneously. My information is that
   no one has had any problem with this system to date. No one
   has mentioned vapour problems.
   George ( down under)




I'd appreciate anyone's experience with using an aftermarket fuel pulse dampener or not using a dampener at all. I know that the RX-7 dampeners tend to leak and spray fuel all over the engine, resulting in engine fires. The RX-8 dampener looks pretty cheezy as well, so I cut mine off the stock fuel rail. I need to decide whether to use no dampener or an aftermarket unit.

Bruce T. says we probably don't need a pulse dampener if you are using 'rubber' hoses, as they will absorb the injector pulses. I'm planning on using 3/8" SS hard lines into the main fuel rail, curving back 180 degrees (through one -6 fitting) to the small rail, then back to the fuel pressure regulator. Since this high-pressure system is over the exhaust, I'd prefer to stay with rigid SS lines to the front of the engine before transitioning to flexible hoses. In this scenario, my flex hoses will be only about 12" long and will be well away from the exhaust. However, they may be not long enough to absorb the injector pulses.

Perhaps this is a non-issue when running at a constant, high rpm? Most dampeners look either very flimsy or very heavy. I found one source for a dampener, but I can't get them to respond with detailed specs yet. http://www.matronics.com/fuelchec/dampener.html

Does anyone have any experience or suggestions in this area?

Scott Gettings
Glass Goose/Renesis

Scott I would call John at Mazdatrix and ask him. He does not
do email I think. He has worked at either Racing Beat or Mazdatrix
his entire adult life rebuilding rotary engines and getting them
to run. 562-426-7960 Very sharp guy on the rotary.
He is under a car right at the moment so call in an hour.
2:45 PM your time might be about right if you are in Florida.
He built both Perry Mick's and Marks Supinski's engines.
We ran Mark's engine without a damper on the dyno but I do not
consider that a definitive test.

Paul Lamar

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