Self Dampening Fuel Rails
Self Dampening Fuel Rails
(OP)
I am interested in Self Dampening Fuel Rails for Low* (2-5 bar) and High Pressure (150 bar plus) Rails, in particular what makes a good (dampening) design of rail and why?
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Self Dampening Fuel Rails
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Self Dampening Fuel RailsSelf Dampening Fuel Rails(OP)
I am interested in Self Dampening Fuel Rails for Low* (2-5 bar) and High Pressure (150 bar plus) Rails, in particular what makes a good (dampening) design of rail and why?
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RE: Self Dampening Fuel Rails
RE: Self Dampening Fuel Rails
For more expert help I'd suggest hitting the guys and gals up on the DIY_EFI mailing list. This is a group of individuals dedicated to nothing but fuel injection. They've helped me out more than once!
Try them at:
http://www.diy-efi.org/
Good Luck
Bryan Carter
RE: Self Dampening Fuel Rails
RE: Self Dampening Fuel Rails
RE: Self Dampening Fuel Rails
Enginead is quite right that it is due to oscillations set up by the injectors & closing. The problem seems to be that these can start up a standing wave that causes resonance related to the injector firing frequency.
I had no problems with a large bore single rail for a V6, but when I had to change it to a twin rail system due to a reposition of the injectors, up to 14% fuelling deviations cylinder/cylinder were the result!
Fuel in ---->=========
Simply modelling the fuel rail as a helmholtz resonator using bulk moduli for fuel & injector rail gave quite good correlation to the problem fuelling areas that were related to engine speed.
The solution was to use a rubber connector between the 2 ends of the fuel rail which solved the problem (so did a braided goodridge hose that had much less damping than the plain rubber hose).
Fuel in ----->========)
I know that returnless V8 systems with twin fuel rails also require a connection between the rails at the opposite end to the fuel inlets.
If you get really stuck, then Bosch in Germany have a test rig that can measure individual fuel flows through the injectors whilst they are fired with a control signal. (I did my validation with them).
Hope this helps!