idc @110% need some insight
08-12-2007, 08:28 PM
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idc @110% need some insight its a 99 full bolt on ported weiand intake with 85mm tb big cam only car stock injectors are 110%? is this because i have 26lb injectors
08-13-2007, 06:33 PM
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Yes it is.
Edit: To go along with SPLATT, 110 is no good, typically you want to stay below 85% at max duty cycle. DC is how long the injector is having to spray to get the desired amount of fuel. 42# injector will have a lower duty cycle than a 26# given the same fuel requirements so it's not working as hard. Also you are probably getting a lot of puddling behind the intake valve because the injector is having to fire for so long to get the right amount of fuel for your cam's given intake duration. Working an injector that hard could cause it to stop working and then you would really be pissed off.
Edit: To go along with SPLATT, 110 is no good, typically you want to stay below 85% at max duty cycle. DC is how long the injector is having to spray to get the desired amount of fuel. 42# injector will have a lower duty cycle than a 26# given the same fuel requirements so it's not working as hard. Also you are probably getting a lot of puddling behind the intake valve because the injector is having to fire for so long to get the right amount of fuel for your cam's given intake duration. Working an injector that hard could cause it to stop working and then you would really be pissed off.
Last edited by ulakovic22; 08-13-2007 at 07:37 PM.
08-17-2007, 10:31 AM
#5
You need to realize that the injector duty cycle seen on a scan is not actual duty cycle, but rather a commanded duty cycle. Once an injector reaches 100% duty cycle, it is on for the entire combustion cycle (720 degrees for a four stroke engine). The ECM has calculated a required duty cycle that is not possible. I wouldn't go to 42lbs injectors, unless you plan on nitrous or more mods, you setup only requires 36lbs injectors (Ford SVO 30lbs). This should put you easily at 85% duty cycle. 
A rule of thumb I use for injector size to rwhp relationship, is as follows (based solely on my experience, others may differ):
Inj (GM Rating) - rwhp (@ 85% DC) [Max @ 95% DC]
28lbs - 400 [430]
36lbs - 550 [600]
42lbs - 700 [760]
60lbs - ~800 [~875]
A rule of thumb I use for injector size to rwhp relationship, is as follows (based solely on my experience, others may differ):
Inj (GM Rating) - rwhp (@ 85% DC) [Max @ 95% DC]
28lbs - 400 [430]
36lbs - 550 [600]
42lbs - 700 [760]
60lbs - ~800 [~875]
08-19-2007, 01:51 PM
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go look at New Era Performance, I got a GOOD deal with their Lucas balanced injectors. I picked up some 42#ers for $380 and that included balancing. they sent a sheet of each injector and the injector was #erd so u know which one was doing what, people say it's better to put the bigger injector in the back like #7 piston. with 43.5psi they came out to be 46.6lb injectors so at our fuel pressure they are about 50# injectors for $380...good deal.
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08-19-2007, 05:55 PM
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what would stock 28# s with the racetronix pump get my duty cylce down to...my buddys got a set laying around. not trying to bandaid it just if i can get it down respecitvley for free(gotta do the pump for the spray anyway) i will throw the 28s in for my tune next wed
08-19-2007, 06:16 PM
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injectors are cheap- injectors are cheap- @ $380 for a set of 8 big injectors are a good price compared to a engine meltdown-
bascially from a kids point of the view-the injector problem u say u have-is that the injector is staying wide open all the time at 110 duty cycle-
it wont last long-it will just give up and shut off one day if u keep pushing-
seen it once and that was enough for me-
bascially from a kids point of the view-the injector problem u say u have-is that the injector is staying wide open all the time at 110 duty cycle-
it wont last long-it will just give up and shut off one day if u keep pushing-
seen it once and that was enough for me-
08-19-2007, 06:24 PM
#12
Originally Posted by 12secSS
You need to realize that the injector duty cycle seen on a scan is not actual duty cycle, but rather a commanded duty cycle. Once an injector reaches 100% duty cycle, it is on for the entire combustion cycle (720 degrees for a four stroke engine). The ECM has calculated a required duty cycle that is not possible. I wouldn't go to 42lbs injectors, unless you plan on nitrous or more mods, you setup only requires 36lbs injectors (Ford SVO 30lbs). This should put you easily at 85% duty cycle.
A rule of thumb I use for injector size to rwhp relationship, is as follows (based solely on my experience, others may differ):
Inj (GM Rating) - rwhp (@ 85% DC) [Max @ 95% DC]
28lbs - 400 [430]
36lbs - 550 [600]
42lbs - 700 [760]
60lbs - ~800 [~875]
A rule of thumb I use for injector size to rwhp relationship, is as follows (based solely on my experience, others may differ):
Inj (GM Rating) - rwhp (@ 85% DC) [Max @ 95% DC]
28lbs - 400 [430]
36lbs - 550 [600]
42lbs - 700 [760]
60lbs - ~800 [~875]
I do think I'm going to go to 42's though since I am not sure what type of nitrous kit I am planning on yet.. but heavily leaning to a direct port. I might try 36's.
What injectors are preffered for the LS1? I use 72# Accel injectors on my GN and they work great.
08-20-2007, 10:37 AM
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money isnt the problem by anymeans...i just thought they were a little inexpensive. No big deal i will do what it takes..so how much does 2# lower the idc from a 110% to ? will have a racetronix kit
08-21-2007, 10:47 PM
#14
Originally Posted by 12secSS
You need to realize that the injector duty cycle seen on a scan is not actual duty cycle, but rather a commanded duty cycle. Once an injector reaches 100% duty cycle, it is on for the entire combustion cycle (720 degrees for a four stroke engine). The ECM has calculated a required duty cycle that is not possible. I wouldn't go to 42lbs injectors, unless you plan on nitrous or more mods, you setup only requires 36lbs injectors (Ford SVO 30lbs). This should put you easily at 85% duty cycle.
A rule of thumb I use for injector size to rwhp relationship, is as follows (based solely on my experience, others may differ):
Inj (GM Rating) - rwhp (@ 85% DC) [Max @ 95% DC]
28lbs - 400 [430]
36lbs - 550 [600]
42lbs - 700 [760]
60lbs - ~800 [~875]
A rule of thumb I use for injector size to rwhp relationship, is as follows (based solely on my experience, others may differ):
Inj (GM Rating) - rwhp (@ 85% DC) [Max @ 95% DC]
28lbs - 400 [430]
36lbs - 550 [600]
42lbs - 700 [760]
60lbs - ~800 [~875]
Mike
08-21-2007, 11:51 PM
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Originally Posted by dpw41285
money isnt the problem by anymeans...i just thought they were a little inexpensive. No big deal i will do what it takes..so how much does 2# lower the idc from a 110% to ? will have a racetronix kit
08-22-2007, 05:00 PM
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here is a good deal...
brand new 60#ers
https://ls1tech.com/forums/showthrea...19#post7372819
they are not flow matched but u could buy them and find a place locally to get it done if u wanted too.
brand new 60#ers
https://ls1tech.com/forums/showthrea...19#post7372819
they are not flow matched but u could buy them and find a place locally to get it done if u wanted too.