injector flow rate/boost compensation
11-12-2008, 04:35 PM
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injector flow rate/boost compensation
currently tuning a gmc sierra 4.8 procharged truck and needing to know a couple of things.
what is the rail pressure on the sierra in from the factory? also, can anyone give me the gph rating of a stock pump and also what psi that is rated at?
another question for people who have tuned and/or are currently running a similar setup
rail pressure must increase 1:1 with boost pressure so that it does not effectively make the injector smaller. Are any of the related members here having any trouble with fuel control because of this. for example you have the right size injectors for the combination and have the injector flow rate table scaled properly but have afr problems etc. etc. because of the boost increase? any info on this would be much appreciated, thanks.
what is the rail pressure on the sierra in from the factory? also, can anyone give me the gph rating of a stock pump and also what psi that is rated at?
another question for people who have tuned and/or are currently running a similar setup
rail pressure must increase 1:1 with boost pressure so that it does not effectively make the injector smaller. Are any of the related members here having any trouble with fuel control because of this. for example you have the right size injectors for the combination and have the injector flow rate table scaled properly but have afr problems etc. etc. because of the boost increase? any info on this would be much appreciated, thanks.
11-12-2008, 04:43 PM
#2
what year of truck? does it have a return fuel line?
if it does have a return line then the factory fuel presure is 3 bar or something like 59psi. the factory fpr is close enough to a 1-1 to work fine. not sure on pump rating for flow or psi but i can tell you it is good to a little over 400rwhp. a simple and cheap extra inline pump will take you to something like 600rwhp.
if it does not have a return line then all the info above is wrong
if it does have a return line then the factory fuel presure is 3 bar or something like 59psi. the factory fpr is close enough to a 1-1 to work fine. not sure on pump rating for flow or psi but i can tell you it is good to a little over 400rwhp. a simple and cheap extra inline pump will take you to something like 600rwhp.
if it does not have a return line then all the info above is wrong
11-12-2008, 05:00 PM
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Being an '04 and it is returnless you will need to scale the IFR table to deliver more fuel as the MAP goes up. There is a XL worksheet around somewhere to help with this based on the injectors that you are using. Redhardsupra has it on his web site. If you search for him you should be able to find it.
The in-tank pump in the '04 has a higher LPH rating than the earlier pumps and you may be able to get away with it for a while if you don't pully up to increase the boost level. Hopefully someone will chime in with more exact information but it is available on here if you search around a bit.
The in-tank pump in the '04 has a higher LPH rating than the earlier pumps and you may be able to get away with it for a while if you don't pully up to increase the boost level. Hopefully someone will chime in with more exact information but it is available on here if you search around a bit.
11-12-2008, 05:19 PM
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Being an '04 and it is returnless you will need to scale the IFR table to deliver more fuel as the MAP goes up. There is a XL worksheet around somewhere to help with this based on the injectors that you are using. Redhardsupra has it on his web site. If you search for him you should be able to find it.
The in-tank pump in the '04 has a higher LPH rating than the earlier pumps and you may be able to get away with it for a while if you don't pully up to increase the boost level. Hopefully someone will chime in with more exact information but it is available on here if you search around a bit.
The in-tank pump in the '04 has a higher LPH rating than the earlier pumps and you may be able to get away with it for a while if you don't pully up to increase the boost level. Hopefully someone will chime in with more exact information but it is available on here if you search around a bit.
Last edited by avb0119; 11-12-2008 at 05:52 PM.
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11-12-2008, 05:31 PM
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I have an '03 so I never bothered to memorize the '04 info except in a general way . The FPR (in-tank) in the '04 is rated at a constant 4 bar pressure (58 psi) as far as I know. The stock pump is probably rated in the 225 LPH range but again I am not 100% sure on that.
Hopefully someone who knows for sure will help you out with this.
Hopefully someone who knows for sure will help you out with this.
11-12-2008, 05:41 PM
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I have an '03 so I never bothered to memorize the '04 info except in a general way . The FPR (in-tank) in the '04 is rated at a constant 4 bar pressure (58 psi) as far as I know. The stock pump is probably rated in the 225 LPH range but again I am not 100% sure on that.
Hopefully someone who knows for sure will help you out with this.
Hopefully someone who knows for sure will help you out with this.
Last edited by avb0119; 11-12-2008 at 05:53 PM.
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