The "ticking and clicking" LT1
10-21-2014, 10:58 AM
#1
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Thread Starter
The "ticking and clicking" LT1
FYI for all you Stingray owners out there who find the Direct Injection noise coming from the LT1 engine to be annoying. I got this info from the Corvette Master Tech at my dealer:
"The LT1 engine uses a direct injection fuel system that operates at very high fuel pressures. A direct injection fuel system produces a rapid clicking and ticking sound that can be heard from the engine compartment. The sound is more evident when outside around the vehicle or when the hood is open. The sound is more noticeable during idle and is more frequent during a cold start, but lessens once the engine is warm. The rapid ticking noise on cold start up is the fuel pump building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. These sounds are the results of a normal direct injection fuel system operating properly."
This sound has bothered me from day one because I grew up in the '70s when a collapsed hydrolic lifter on a small block Chevy engine made the exact same sound...or at least it seems that way. My LS3 powered Corvettes make a similar sound but it's not nearly as noticeable (not DI).
Let me know what you think, any and all comments welcome.
"The LT1 engine uses a direct injection fuel system that operates at very high fuel pressures. A direct injection fuel system produces a rapid clicking and ticking sound that can be heard from the engine compartment. The sound is more evident when outside around the vehicle or when the hood is open. The sound is more noticeable during idle and is more frequent during a cold start, but lessens once the engine is warm. The rapid ticking noise on cold start up is the fuel pump building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. These sounds are the results of a normal direct injection fuel system operating properly."
This sound has bothered me from day one because I grew up in the '70s when a collapsed hydrolic lifter on a small block Chevy engine made the exact same sound...or at least it seems that way. My LS3 powered Corvettes make a similar sound but it's not nearly as noticeable (not DI).
Let me know what you think, any and all comments welcome.
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kevstaarr (01-28-2020)
10-21-2014, 11:07 AM
#2
E-Ray, 3LZ, ZER, LIFT
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FYI for all you Stingray owners out there who find the Direct Injection noise coming from the LT1 engine to be annoying. I got this info from the Corvette Master Tech at my dealer:
"The LT1 engine uses a direct injection fuel system that operates at very high fuel pressures. A direct injection fuel system produces a rapid clicking and ticking sound that can be heard from the engine compartment. The sound is more evident when outside around the vehicle or when the hood is open. The sound is more noticeable during idle and is more frequent during a cold start, but lessens once the engine is warm. The rapid ticking noise on cold start up is the fuel pump building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. These sounds are the results of a normal direct injection fuel system operating properly."
This sound has bothered me from day one because I grew up in the '70s when a collapsed hydrolic lifter on a small block Chevy engine made the exact same sound...or at least it seems that way. My LS3 powered Corvettes make a similar sound but it's not nearly as noticeable (not DI).
Let me know what you think, any and all comments welcome.
"The LT1 engine uses a direct injection fuel system that operates at very high fuel pressures. A direct injection fuel system produces a rapid clicking and ticking sound that can be heard from the engine compartment. The sound is more evident when outside around the vehicle or when the hood is open. The sound is more noticeable during idle and is more frequent during a cold start, but lessens once the engine is warm. The rapid ticking noise on cold start up is the fuel pump building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. These sounds are the results of a normal direct injection fuel system operating properly."
This sound has bothered me from day one because I grew up in the '70s when a collapsed hydrolic lifter on a small block Chevy engine made the exact same sound...or at least it seems that way. My LS3 powered Corvettes make a similar sound but it's not nearly as noticeable (not DI).
Let me know what you think, any and all comments welcome.
As you get older that high frequency noise becomes less of a problem, especially when it is from by wife wanting something done in the yard!
10-21-2014, 11:09 AM
#3
Moderator
Yep, very common on DI engines. This is my 4th DI engine (3 on Cadillac's). They all do it.
10-21-2014, 03:34 PM
#4
FYI for all you Stingray owners out there who find the Direct Injection noise coming from the LT1 engine to be annoying. I got this info from the Corvette Master Tech at my dealer:
"The LT1 engine uses a direct injection fuel system that operates at very high fuel pressures. A direct injection fuel system produces a rapid clicking and ticking sound that can be heard from the engine compartment. The sound is more evident when outside around the vehicle or when the hood is open. The sound is more noticeable during idle and is more frequent during a cold start, but lessens once the engine is warm. The rapid ticking noise on cold start up is the fuel pump building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. These sounds are the results of a normal direct injection fuel system operating properly."
This sound has bothered me from day one because I grew up in the '70s when a collapsed hydrolic lifter on a small block Chevy engine made the exact same sound...or at least it seems that way. My LS3 powered Corvettes make a similar sound but it's not nearly as noticeable (not DI).
Let me know what you think, any and all comments welcome.
"The LT1 engine uses a direct injection fuel system that operates at very high fuel pressures. A direct injection fuel system produces a rapid clicking and ticking sound that can be heard from the engine compartment. The sound is more evident when outside around the vehicle or when the hood is open. The sound is more noticeable during idle and is more frequent during a cold start, but lessens once the engine is warm. The rapid ticking noise on cold start up is the fuel pump building up high fuel pressure. When the engine warm-up is completed, the high pressure fuel pump will continue to tick at a lower rate of approximately one tick per second during idle. The clicking sound is the fuel injectors pulsing on and off under higher fuel pressures. These sounds are the results of a normal direct injection fuel system operating properly."
This sound has bothered me from day one because I grew up in the '70s when a collapsed hydrolic lifter on a small block Chevy engine made the exact same sound...or at least it seems that way. My LS3 powered Corvettes make a similar sound but it's not nearly as noticeable (not DI).
Let me know what you think, any and all comments welcome.
posted it awhile back( but it up and was gone )
this is also the noise that people are hearing from the dash like a small fan or motorhope this stays on here
10-21-2014, 03:52 PM
#5
Moderator
Totally wrong.
The injectors, which feature 6 holes each and specially designed injector spray and droplet patterns, have a flow rate of 125.7 lbs/hr at 1,450 psi, and can be fed up to 2,175 psi from the 1.48 cc/rev geometric displacement fuel pump. The pump is mechanical (fed by an electric in-tank unit) and is driven off the rear of the tri-lobe camshaft.
10-21-2014, 03:54 PM
#6
Thanks for posting. I've been researching this sound over the past week. I have close to 700 miles but I don't remember hearing the sound the first few hundred miles. I'm sure it was there, guess I just didn't notice it. It sucks driving by at slow speed though. From the front you hear the clicking before the low exhaust.
10-21-2014, 03:56 PM
#7
Some NON-metallic ticking sound is normal on DI engines. However, some C7's (per several members threads with dealer findings/confirmations) have exhibited other ticks/knocking sounds from the engine that are abnormal and unrelated to the direct injection sounding characteristic in itself.
10-21-2014, 04:41 PM
#8
D.I. fuel pump is located at the rear of the engine valley'''''' thats a long ways from the tank pumps
maybe this will help some people .................read about mid way down.
http://www.zorly.com/speed-wars/LT1-...e-GM-Chevrolet
maybe this will help some people .................read about mid way down.
http://www.zorly.com/speed-wars/LT1-...e-GM-Chevrolet
Last edited by lastcowboy; 10-21-2014 at 04:55 PM.
10-21-2014, 05:02 PM
#10
Good explanation, in my opinion. Just like a diesel, having to close the injectors against 2000+ psi fuel pressure versus port injection of perhaps 60 psi mean a lot more closing force and noise. However they do have an insulating material in the intake manifold valley that stops a lot of noise from the pump and injectors.
As you get older that high frequency noise becomes less of a problem, especially when it is from by wife wanting something done in the yard!
As you get older that high frequency noise becomes less of a problem, especially when it is from by wife wanting something done in the yard!
anyway its wraped in a high impact foam and you think its loud now you should hear it with out that foam .
10-21-2014, 05:03 PM
#11
Moderator
I suggest you read it again:
15Mpa or 150bar is 2,175 PSI.
Cam powered high pressure fuel pump: There is a high-pressure fuel pump mounted between the cylinder heads on top of the LOMA (Lifter Oil Manifold Assembly) / combination valley cover which sits under the insulated intake manifold for perceived quieter operations. This cam powered high pressure fuel pump #2 is required to bring the pressures up to what is needed (maximum of 15Mpa or 150bar) for the direct fuel injection system. In addition there is also your standard type fuel pump mounted in the fuel tank.
15Mpa or 150bar is 2,175 PSI.
10-21-2014, 05:51 PM
#12
10-21-2014, 06:07 PM
#13
Moderator
Huh? The fuel pump in question is the high pressure pump in the engine valley. The pressure is 2,000+ PSI, not the 60-300 PSI your S. Mgr quoted. The DI noise is a result of the high pressure (2,000+ PSI). Both the article I quoted and the article you quoted both say the pressure is 2,000+ PSI (your article uses 15Mpa but that is another unit of measure that is equivalent to 2,175 PSI).
10-21-2014, 06:48 PM
#14
E-Ray, 3LZ, ZER, LIFT
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Two different pumps. A relatively low pressure pump in the tank delivers gas to the high pressure pump in the lifter valley! That is the one covered with insulation. The one in the tank is covered with gas!
10-21-2014, 07:05 PM
#16
Huh? The fuel pump in question is the high pressure pump in the engine valley. The pressure is 2,000+ PSI, not the 60-300 PSI your S. Mgr quoted. The DI noise is a result of the high pressure (2,000+ PSI). Both the article I quoted and the article you quoted both say the pressure is 2,000+ PSI (your article uses 15Mpa but that is another unit of measure that is equivalent to 2,175 PSI).
is the ser. mgr. right on the psi.? i don't know, he could be talking about somethig diff. that has to do with the 2k of pressure .he said it was comming from the valley of the motor from the fuel pump located there .for all i know he was deviding it between 8c.
he is a rep. for gm after all . i will pass along these findings when i see him and tell him hes wrong about the psi......but whatever anyone says the f. pump is causing the noise .
