Noisy Fuel RAIL Dampers???
10-18-2011, 11:14 AM
#1
Burning Brakes
Thread Starter
Noisy Fuel RAIL Dampers???
Does anyone have really good insight into the fuel rail design on the LS1/LS6?
Doing a bit of Googling I came across a site for Delphi fuel rails:
http://delphi.com/manufacturers/auto...s/injsys/mpfi/
A quote from this site:
"Delphi's MPFI Fuel Rail damping technology can significantly reduce pressure pulsation levels. As a pressure wave travels in a conduit, it locally deflects the Delphi-designed damping surfaces, decreasing pressure pulsations. The reduction of pressure pulsations improves cylinder-to-cylinder fuel distribution, improves pulse-to-pulse fueling control and reduces chassis line vibrations. This technology helps improve drivability, reduce emissions and minimize fuel line noise."
Now, I understand the purpose and application of a typical mechanical fuel rail pressure damper (which I believe the LS1/6 fuel rails have, the unit in the middle attached to the crossover tube). It is there to smooth out mechanical noise in the fuel system by damping the pressure pulses resulting from opening and closing fuel injectors.
What I'm curious about is a damper that's located inside the fuel rail itself, right above the injectors. When I had my injectors out I could see some sort of contraption inside the rail. According to the Delphi information above, what I saw could be a "damping surface" designed to reduce pressure pulsations within the rail itself and ensure even fuel distribution to all injectors.
I'm having issues with a noisy top end, and extensive listening with a stethoscope leads me to believe the noise is injector/rail related (listening to the block and heads does not reveal any loud ticking/clacking noises). Scoping each individual injector reveals they are LOUD, some sounding a little different than others, but for the most part the same. I have mechanically isolated the injectors from the fuel rail (removed the steel clips that hold the injectors to the rail) and the noise remains. Don't worry, I put an extra set of injector o-rings in the intake manifold below the injectors to hold them up into the rail…
I'm wondering if the clatter I'm hearing is the result of a fuel rail damper coming loose and slapping around inside the rail? Has anyone else experienced this or looked into it?
I'm also wondering if anyone using aftermarket fuel rails has experienced uneven fuel distribution? This is assuming the aftermarket rails are NOT using any sort of internal "damping surface", but instead relying on larger volume rails to limit pressure fluctuations from one injector to the next. I'm entertaining the thought of aftermarket fuel rails if it's the only way to rid myself of this noisy motor… listening to it clacking away is constantly making me nervous that I have a bad lifter or something (once again, I listened to the block and heads with a stethescope and all seems well internally).
Doing a bit of Googling I came across a site for Delphi fuel rails:
http://delphi.com/manufacturers/auto...s/injsys/mpfi/
A quote from this site:
"Delphi's MPFI Fuel Rail damping technology can significantly reduce pressure pulsation levels. As a pressure wave travels in a conduit, it locally deflects the Delphi-designed damping surfaces, decreasing pressure pulsations. The reduction of pressure pulsations improves cylinder-to-cylinder fuel distribution, improves pulse-to-pulse fueling control and reduces chassis line vibrations. This technology helps improve drivability, reduce emissions and minimize fuel line noise."
Now, I understand the purpose and application of a typical mechanical fuel rail pressure damper (which I believe the LS1/6 fuel rails have, the unit in the middle attached to the crossover tube). It is there to smooth out mechanical noise in the fuel system by damping the pressure pulses resulting from opening and closing fuel injectors.
What I'm curious about is a damper that's located inside the fuel rail itself, right above the injectors. When I had my injectors out I could see some sort of contraption inside the rail. According to the Delphi information above, what I saw could be a "damping surface" designed to reduce pressure pulsations within the rail itself and ensure even fuel distribution to all injectors.
I'm having issues with a noisy top end, and extensive listening with a stethoscope leads me to believe the noise is injector/rail related (listening to the block and heads does not reveal any loud ticking/clacking noises). Scoping each individual injector reveals they are LOUD, some sounding a little different than others, but for the most part the same. I have mechanically isolated the injectors from the fuel rail (removed the steel clips that hold the injectors to the rail) and the noise remains. Don't worry, I put an extra set of injector o-rings in the intake manifold below the injectors to hold them up into the rail…
I'm wondering if the clatter I'm hearing is the result of a fuel rail damper coming loose and slapping around inside the rail? Has anyone else experienced this or looked into it?
I'm also wondering if anyone using aftermarket fuel rails has experienced uneven fuel distribution? This is assuming the aftermarket rails are NOT using any sort of internal "damping surface", but instead relying on larger volume rails to limit pressure fluctuations from one injector to the next. I'm entertaining the thought of aftermarket fuel rails if it's the only way to rid myself of this noisy motor… listening to it clacking away is constantly making me nervous that I have a bad lifter or something (once again, I listened to the block and heads with a stethescope and all seems well internally).
10-18-2011, 11:34 AM
#2
Tech Contributor
Does anyone have really good insight into the fuel rail design on the LS1/LS6?
Doing a bit of Googling I came across a site for Delphi fuel rails:
http://delphi.com/manufacturers/auto...s/injsys/mpfi/
A quote from this site:
"Delphi's MPFI Fuel Rail damping technology can significantly reduce pressure pulsation levels. As a pressure wave travels in a conduit, it locally deflects the Delphi-designed damping surfaces, decreasing pressure pulsations. The reduction of pressure pulsations improves cylinder-to-cylinder fuel distribution, improves pulse-to-pulse fueling control and reduces chassis line vibrations. This technology helps improve drivability, reduce emissions and minimize fuel line noise."
Now, I understand the purpose and application of a typical mechanical fuel rail pressure damper (which I believe the LS1/6 fuel rails have, the unit in the middle attached to the crossover tube). It is there to smooth out mechanical noise in the fuel system by damping the pressure pulses resulting from opening and closing fuel injectors.
What I'm curious about is a damper that's located inside the fuel rail itself, right above the injectors. When I had my injectors out I could see some sort of contraption inside the rail. According to the Delphi information above, what I saw could be a "damping surface" designed to reduce pressure pulsations within the rail itself and ensure even fuel distribution to all injectors.
I'm having issues with a noisy top end, and extensive listening with a stethoscope leads me to believe the noise is injector/rail related (listening to the block and heads does not reveal any loud ticking/clacking noises). Scoping each individual injector reveals they are LOUD, some sounding a little different than others, but for the most part the same. I have mechanically isolated the injectors from the fuel rail (removed the steel clips that hold the injectors to the rail) and the noise remains. Don't worry, I put an extra set of injector o-rings in the intake manifold below the injectors to hold them up into the rail…
I'm wondering if the clatter I'm hearing is the result of a fuel rail damper coming loose and slapping around inside the rail? Has anyone else experienced this or looked into it?
I'm also wondering if anyone using aftermarket fuel rails has experienced uneven fuel distribution? This is assuming the aftermarket rails are NOT using any sort of internal "damping surface", but instead relying on larger volume rails to limit pressure fluctuations from one injector to the next. I'm entertaining the thought of aftermarket fuel rails if it's the only way to rid myself of this noisy motor… listening to it clacking away is constantly making me nervous that I have a bad lifter or something (once again, I listened to the block and heads with a stethescope and all seems well internally).
Doing a bit of Googling I came across a site for Delphi fuel rails:
http://delphi.com/manufacturers/auto...s/injsys/mpfi/
A quote from this site:
"Delphi's MPFI Fuel Rail damping technology can significantly reduce pressure pulsation levels. As a pressure wave travels in a conduit, it locally deflects the Delphi-designed damping surfaces, decreasing pressure pulsations. The reduction of pressure pulsations improves cylinder-to-cylinder fuel distribution, improves pulse-to-pulse fueling control and reduces chassis line vibrations. This technology helps improve drivability, reduce emissions and minimize fuel line noise."
Now, I understand the purpose and application of a typical mechanical fuel rail pressure damper (which I believe the LS1/6 fuel rails have, the unit in the middle attached to the crossover tube). It is there to smooth out mechanical noise in the fuel system by damping the pressure pulses resulting from opening and closing fuel injectors.
What I'm curious about is a damper that's located inside the fuel rail itself, right above the injectors. When I had my injectors out I could see some sort of contraption inside the rail. According to the Delphi information above, what I saw could be a "damping surface" designed to reduce pressure pulsations within the rail itself and ensure even fuel distribution to all injectors.
I'm having issues with a noisy top end, and extensive listening with a stethoscope leads me to believe the noise is injector/rail related (listening to the block and heads does not reveal any loud ticking/clacking noises). Scoping each individual injector reveals they are LOUD, some sounding a little different than others, but for the most part the same. I have mechanically isolated the injectors from the fuel rail (removed the steel clips that hold the injectors to the rail) and the noise remains. Don't worry, I put an extra set of injector o-rings in the intake manifold below the injectors to hold them up into the rail…
I'm wondering if the clatter I'm hearing is the result of a fuel rail damper coming loose and slapping around inside the rail? Has anyone else experienced this or looked into it?
I'm also wondering if anyone using aftermarket fuel rails has experienced uneven fuel distribution? This is assuming the aftermarket rails are NOT using any sort of internal "damping surface", but instead relying on larger volume rails to limit pressure fluctuations from one injector to the next. I'm entertaining the thought of aftermarket fuel rails if it's the only way to rid myself of this noisy motor… listening to it clacking away is constantly making me nervous that I have a bad lifter or something (once again, I listened to the block and heads with a stethescope and all seems well internally).
So if I understand correctly, you think you have a fuel rail problem, and it just so happens, that all 8 positions are exhibiting the same behavior/noise? You are absolutely certain, that the noise you are hearing, could not be coming from the motor, valve train, etc? Also, what injectors are you using, and have you tried swapping in a different brand, to see if the noise changes?
10-18-2011, 11:47 AM
#3
Burning Brakes
Thread Starter
'02 LS6, stock injectors. Have not tried others.
Through a scope block and heads sound smooth and quiet, injectors and rails are noisy.
Noise sounds like one injector banging away (one tap every other engine revolution), but no one injector seems to scope much louder than the others. If all eight injectors were contributing there would just be a constant "clatter", not a distinct "tap-tap-tap", this is what's leading me to suspect a "baffle" or "damping surface" inside a rail may be loose.
I don't think aftermarket fuel rails have "damping surfaces" engineered into them, hence my question regarding even fuel distribution in aftermarket rails.
Through a scope block and heads sound smooth and quiet, injectors and rails are noisy.
Noise sounds like one injector banging away (one tap every other engine revolution), but no one injector seems to scope much louder than the others. If all eight injectors were contributing there would just be a constant "clatter", not a distinct "tap-tap-tap", this is what's leading me to suspect a "baffle" or "damping surface" inside a rail may be loose.
I don't think aftermarket fuel rails have "damping surfaces" engineered into them, hence my question regarding even fuel distribution in aftermarket rails.
10-18-2011, 12:00 PM
#4
Tech Contributor
'02 LS6, stock injectors. Have not tried others.
Through a scope block and heads sound smooth and quiet, injectors and rails are noisy.
Noise sounds like one injector banging away (one tap every other engine revolution), but no one injector seems to scope much louder than the others. If all eight injectors were contributing there would just be a constant "clatter", not a distinct "tap-tap-tap", this is what's leading me to suspect a "baffle" or "damping surface" inside a rail may be loose.
I don't think aftermarket fuel rails have "damping surfaces" engineered into them, hence my question regarding even fuel distribution in aftermarket rails.
Through a scope block and heads sound smooth and quiet, injectors and rails are noisy.
Noise sounds like one injector banging away (one tap every other engine revolution), but no one injector seems to scope much louder than the others. If all eight injectors were contributing there would just be a constant "clatter", not a distinct "tap-tap-tap", this is what's leading me to suspect a "baffle" or "damping surface" inside a rail may be loose.
I don't think aftermarket fuel rails have "damping surfaces" engineered into them, hence my question regarding even fuel distribution in aftermarket rails.
10-18-2011, 12:38 PM
#5
Burning Brakes
Thread Starter
"Pressure damping options include:
- Undamped ("Tech 0") Fuel Rails in both stainless steel and composite material designs that provide a low cost option for applications without fuel distribution issues.
- Internally Damped ("Tech 1") Fuel Rails, also available in both stainless steel and composite material designs, feature a stainless steel damper positioned inside the fuel rail conduit directly over the injectors. The damper is robust to thermal and flexible fuel environments. Pulsations are dampened at the injector source.
- Integrally Damped ("Tech 2") Fuel Rails are made of stainless steel. The conduit walls act as the damping surface to eliminate the internal damper."
I believe the LS1/6 fuel rails are the "Tech 1" type, stainless steel conduit with internal stainless steel damper.
Based on their description, I would assume the "Integrally Damped Tech 2" design would have resonant features formed into the walls of the main conduit. LS1/6 fuel rails do not appear to have such features, they appear to be smooth straight tubing.
10-18-2011, 12:56 PM
#6
Tech Contributor
From the Delphi page:
"Pressure damping options include:
- Undamped ("Tech 0") Fuel Rails in both stainless steel and composite material designs that provide a low cost option for applications without fuel distribution issues.
- Internally Damped ("Tech 1") Fuel Rails, also available in both stainless steel and composite material designs, feature a stainless steel damper positioned inside the fuel rail conduit directly over the injectors. The damper is robust to thermal and flexible fuel environments. Pulsations are dampened at the injector source.
- Integrally Damped ("Tech 2") Fuel Rails are made of stainless steel. The conduit walls act as the damping surface to eliminate the internal damper."
I believe the LS1/6 fuel rails are the "Tech 1" type, stainless steel conduit with internal stainless steel damper.
Based on their description, I would assume the "Integrally Damped Tech 2" design would have resonant features formed into the walls of the main conduit. LS1/6 fuel rails do not appear to have such features, they appear to be smooth straight tubing.
"Pressure damping options include:
- Undamped ("Tech 0") Fuel Rails in both stainless steel and composite material designs that provide a low cost option for applications without fuel distribution issues.
- Internally Damped ("Tech 1") Fuel Rails, also available in both stainless steel and composite material designs, feature a stainless steel damper positioned inside the fuel rail conduit directly over the injectors. The damper is robust to thermal and flexible fuel environments. Pulsations are dampened at the injector source.
- Integrally Damped ("Tech 2") Fuel Rails are made of stainless steel. The conduit walls act as the damping surface to eliminate the internal damper."
I believe the LS1/6 fuel rails are the "Tech 1" type, stainless steel conduit with internal stainless steel damper.
Based on their description, I would assume the "Integrally Damped Tech 2" design would have resonant features formed into the walls of the main conduit. LS1/6 fuel rails do not appear to have such features, they appear to be smooth straight tubing.
