Fuel Pressure: Up, Up and Away!
Oct 26, 2005 | 11:36 PM
#31
here is a little info, it's not the site i was thinking of but it is a start. >> http://www.injector.com/faq.php#faq1
Oct 26, 2005 | 11:56 PM
#32
Oct 27, 2005 | 12:26 AM
#33
Both of those sites have lots of good info. I like the hp per injector based off different BSFC.
I'm not sure what you or Delphi is talking about 02sierraz71_5.3. I think all they were saying is that thier injectors rated conservatively at 100%. Like a 24lb/hr can really flow 28 or something. You know the CYA, cover your *** policy.
Or maybe they advertise 80% duty cycle which means they'll flow more at 100%.
I'm not sure what you or Delphi is talking about 02sierraz71_5.3. I think all they were saying is that thier injectors rated conservatively at 100%. Like a 24lb/hr can really flow 28 or something. You know the CYA, cover your *** policy.
Or maybe they advertise 80% duty cycle which means they'll flow more at 100%.
Oct 27, 2005 | 12:32 AM
#34
Originally Posted by vanillagorilla
Both of those sites have lots of good info. I like the hp per injector based off different BSFC.
I'm not sure what you or Delphi is talking about 02sierraz71_5.3. I think all they were saying is that thier injectors rated conservatively at 100%. Like a 24lb/hr can really flow 28 or something. You know the CYA, cover your *** policy. Or maybe they advertise 80% duty cycle which means they'll flow more at 100%.
I'm not sure what you or Delphi is talking about 02sierraz71_5.3. I think all they were saying is that thier injectors rated conservatively at 100%. Like a 24lb/hr can really flow 28 or something. You know the CYA, cover your *** policy.
Or maybe they advertise 80% duty cycle which means they'll flow more at 100%.
lots of good head flow data there too
Oct 27, 2005 | 06:30 AM
#35
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[QUOTE=parish8]
whoa!!!! not sure who this chuck guy is but he needs to go back to school.
let me say again. the injectors are rated at wide open(100%duty cycle).
if you see 100% duty cycle on your logger then the injector is wide open, that is known as "static". static means the pintle or disk or whatever is in there in no longer moving. it is just held open. some say going static is bad for the injector but most say it doesn't hury anything. once you are at 100% duty cycle there is no more fuel to be had from those injectors. they can not give any more than 100%.
at 6000rpm there is 20ms thru 2revolutions. 2 revolutions is how far the motor turns before the cycle starts over. if the computer asks for 22ms of pulse width then it will be asking for a longer pulse width then there is time for. that is when the duty cycle can show over 100%. in reality there is only 20ms(at 6000rpm) for the injector to be open so going 22ms or over 100% duty cycle isn't posiable.
i used to have some great links on fuel systems and how they work but i seem to have lost them. i will try and find them.
so if i'm seeing 23ms that's a bad thing right? should i upgrade the injectors to 60lb/hr?
Originally Posted by 02sierraz71_5.3
whoa!!!! not sure who this chuck guy is but he needs to go back to school.
let me say again. the injectors are rated at wide open(100%duty cycle).
if you see 100% duty cycle on your logger then the injector is wide open, that is known as "static". static means the pintle or disk or whatever is in there in no longer moving. it is just held open. some say going static is bad for the injector but most say it doesn't hury anything. once you are at 100% duty cycle there is no more fuel to be had from those injectors. they can not give any more than 100%.
at 6000rpm there is 20ms thru 2revolutions. 2 revolutions is how far the motor turns before the cycle starts over. if the computer asks for 22ms of pulse width then it will be asking for a longer pulse width then there is time for. that is when the duty cycle can show over 100%. in reality there is only 20ms(at 6000rpm) for the injector to be open so going 22ms or over 100% duty cycle isn't posiable.
i used to have some great links on fuel systems and how they work but i seem to have lost them. i will try and find them.
so if i'm seeing 23ms that's a bad thing right? should i upgrade the injectors to 60lb/hr?
Oct 27, 2005 | 06:42 AM
#36
[QUOTE=DanaliHD]
so if i'm seeing 23ms that's a bad thing right? should i upgrade the injectors to 60lb/hr?
you have a little diferent set up so it is hard to say. did you ditch the whipple fmu? if you got rid of that then yes you should upgrade but if it is still on there then you are geting some fuel that the stock computer doesn't know about. you also have the meth(more fuel). so even though you are injectors are maxed you may not be out of fuel.
then there is the question of tuning. you can max any injector if you run it way too rich. if your under 11.0/1 then leaning it out to 11.5/1 or 12/1 would bring that duty cycle down and make it run better too.
bottom line for me is when i go lean. if i can't get to my desired a/f ratio then it is time to upgrade. the thing about doing it this way is you need to watch it prety close. you might be ok on a dyno but get out on the street on a cold day and you will use more fuel.
Originally Posted by parish8
so if i'm seeing 23ms that's a bad thing right? should i upgrade the injectors to 60lb/hr?
you have a little diferent set up so it is hard to say. did you ditch the whipple fmu? if you got rid of that then yes you should upgrade but if it is still on there then you are geting some fuel that the stock computer doesn't know about. you also have the meth(more fuel). so even though you are injectors are maxed you may not be out of fuel.
then there is the question of tuning. you can max any injector if you run it way too rich. if your under 11.0/1 then leaning it out to 11.5/1 or 12/1 would bring that duty cycle down and make it run better too.
bottom line for me is when i go lean. if i can't get to my desired a/f ratio then it is time to upgrade. the thing about doing it this way is you need to watch it prety close. you might be ok on a dyno but get out on the street on a cold day and you will use more fuel.
Oct 27, 2005 | 07:39 AM
#37
Originally Posted by vanillagorilla
Both of those sites have lots of good info. I like the hp per injector based off different BSFC.
I'm not sure what you or Delphi is talking about 02sierraz71_5.3. I think all they were saying is that thier injectors rated conservatively at 100%. Like a 24lb/hr can really flow 28 or something. You know the CYA, cover your *** policy. Or maybe they advertise 80% duty cycle which means they'll flow more at 100%.
I'm not sure what you or Delphi is talking about 02sierraz71_5.3. I think all they were saying is that thier injectors rated conservatively at 100%. Like a 24lb/hr can really flow 28 or something. You know the CYA, cover your *** policy.
Or maybe they advertise 80% duty cycle which means they'll flow more at 100%.duty cycle=injpw*rpm/1200
someone mentioned 20ms at 6000 rpm thats a 100% duty cycle but according to the principle that the injector cant flow anymore fuel after 100% duty cycle if you were to go over 100%, WHICH YOU CAN DO!!! you would run into a lean condition and that just isnt true. This is why gorilla is getting away with the injectors he is using.
here is an informative post I made on ls1tech got some good info on our trucks from racetronix
https://ls1tech.com/forums/showthrea...ght=duty+cycle
Last edited by 02sierraz71_5.3; Oct 27, 2005 at 09:24 AM.
Oct 27, 2005 | 03:51 PM
#38
i really dont know how to explain it any better than i have but you are missunderstanding how this all works.
i will try one more time.
at 6000rpm there is 20ms avaliable for the injector to be open before the cycle starts over. if the computer comands the injector to be open 22ms then the injector will just never close. that is called static. you no longer have any control over how much fuel you get. this doesn't mean you will instantly go lean, it just means the injector is puting out all the fuel it can.
one more time. an injector can not be open more than 100% of the time. the computer can ask it to be but once it gets to 100% then it is wide open(static) and adding duty cycle to that will do nothing.
i will try one more time.
at 6000rpm there is 20ms avaliable for the injector to be open before the cycle starts over. if the computer comands the injector to be open 22ms then the injector will just never close. that is called static. you no longer have any control over how much fuel you get. this doesn't mean you will instantly go lean, it just means the injector is puting out all the fuel it can.
one more time. an injector can not be open more than 100% of the time. the computer can ask it to be but once it gets to 100% then it is wide open(static) and adding duty cycle to that will do nothing.
Oct 27, 2005 | 04:13 PM
#40
Originally Posted by NoChrome
Ok with no intent to hijack here when upgrading the fuel system is it better to get a 255lph in tank, or leave the in tank alone and get the 255lph inline?
does an intank pump swap cause any fuel starvation issues? the stock pump has some kind of bucket it fills so you never run out of gas even with a low fuel level, does the replacement keep this feature? my duel intank set up will suck air if i am under 1/2 a tank and launch it hard but it does feed a ton of fuel and is prety much plug and play.