basic plumbing for pulsed fuel injection
basic plumbing for pulsed fuel injection
(OP)
In the process of re-plumbing my underhood fuel lines to convert my car to pulsed fuel injection, I am debating the best plumbing scheme.
Engine is an I4, all four injectors will fire simultaneously. Calculated injector size is 26#/hr.
In most systems, the main fuel flow follows this route:
Pump -> Filter -> Rail -> Regulator -> Tank (in series)
In order to clean up the underhood plumbing, I am considering:
Pump -> Filter -> Regulator (tee to Rail), -> Tank
This would eliminate the fuel return line from the rail and physically clean up the installation. I am concerned about rail pressure pulsations and the possibility that the far-end injectors may starve (since I'd be feeding one end of the rail vs the center). Are these valid concerns? Can an accumulator/damper/snubber be effectively used at the end of the rail to reduce pressure pulsations?
Or should I just stop thinking and do it like everybody else?
Thx -
Ron
Engine is an I4, all four injectors will fire simultaneously. Calculated injector size is 26#/hr.
In most systems, the main fuel flow follows this route:
Pump -> Filter -> Rail -> Regulator -> Tank (in series)
In order to clean up the underhood plumbing, I am considering:
Pump -> Filter -> Regulator (tee to Rail), -> Tank
This would eliminate the fuel return line from the rail and physically clean up the installation. I am concerned about rail pressure pulsations and the possibility that the far-end injectors may starve (since I'd be feeding one end of the rail vs the center). Are these valid concerns? Can an accumulator/damper/snubber be effectively used at the end of the rail to reduce pressure pulsations?
Or should I just stop thinking and do it like everybody else?
Thx -
Ron





RE: basic plumbing for pulsed fuel injection
It requires a bit longer fuel line, so OEM's would not do that if they thought they could save a few cewnts worth of line.
Regards
pat
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: basic plumbing for pulsed fuel injection
Cheers
Greg Locock
RE: basic plumbing for pulsed fuel injection
Note that some modern systems use a returnless system. These are much harder to program as they do not maintain a constant pressure drop across the injectors and thus the injector flow is no longer just a function of pulsewidth. The ECU has to calculate the injector flow rate based on MAP sensor input. This is a cheaper system in high volume production since processing power is getting cheaper all the time and any hardware eliminated saves cost. These systems tend to run higher rail pressures to eliminate hot start problems caused by fuel vapor in the injectors/rail.
RE: basic plumbing for pulsed fuel injection
Some pressure pulsations, especially when group firing, may be hard to get rid of. I posted last month with a problem we were having on a custom fuel rail set-up. We applied 4 dampers to the system to get things managed. Testing shall prove worthwhile.
I would suggest returning from one end of the rail and damping the other end.
Happy Wrenching!
RE: basic plumbing for pulsed fuel injection
Oh well, if we don't think...we don't think.
Thx,
Ron