DOC something you said today.. 36/37lb injectors home brew kits and then crushed stock 4bar FP
02-05-2005, 09:51 PM
#1
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DOC something you said today.. 36/37lb injectors home brew kits and then crushed stock 4bar FP
I'm a bit confused
If your going with the 36lb @ 3bar injectors, due to better idle characteristics (faster response injectors?).
That is around 42lb injectors at 4bar, right?, so then going to a 5bar, your running close to what 56lb..
So why exactly are people screwing with the FPR when they are running the 36lb injectors?
Confused , but it's not the first time nor the last
Tory
If your going with the 36lb @ 3bar injectors, due to better idle characteristics (faster response injectors?).
That is around 42lb injectors at 4bar, right?, so then going to a 5bar, your running close to what 56lb..
So why exactly are people screwing with the FPR when they are running the 36lb injectors?
Confused , but it's not the first time nor the last
Tory
02-05-2005, 10:16 PM
#2
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Less fuel needs to be pulled back with 36 # dark blue tops @ 5bar than 42 # green tops @ 4bar.
That would make me think, obviously, that 42 # green tops @ 4bar flow more than 36 # dark blue tops @ 5 bar. All I know is you have to pull back at least 10% more fuel with green tops @ 4bar than with dark blue tops @ 5bar. Maybe someone else can chime in with the exact flow at each fuel pressure. I can say for sure....it works VERY WELL.<ul><li><a href="http://www.gnttype.org/techarea/pictureguides/injectors/36lb.html">36# Dark Blue Top Injector</a></li></ul>
02-05-2005, 10:41 PM
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You know my view on injector sizing:
Use the largest injector that can idle the car smoothly at around stock idle speed and fuel pressure.
There's an extreme margin of fuel on our engines stock 250bhp for a reason, and I think maintaining that margin is prudent in avoiding an enginesplode
You run a smaller injector with more fuel pressure you will run into pulsewidth saturation in, say and EGT enrich situation, before you will running a larger squirter at lower fuel pressure.
There's an extreme margin of fuel on our engines stock 250bhp for a reason, and I think maintaining that margin is prudent in avoiding an enginesplode
You run a smaller injector with more fuel pressure you will run into pulsewidth saturation in, say and EGT enrich situation, before you will running a larger squirter at lower fuel pressure.
02-06-2005, 02:02 AM
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Ummm. can't tell much from that picture.
Except that the picture is teh suck, of course. If you read the pn off the side of the housing you should be able to figure it out quickly.
02-06-2005, 05:51 AM
#6
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looks like green is about 4% larger - math...
Assuming my #'s are correct...
Blue: 36lb@3bar * 10.5 = 378cc/min@3bar
Green: 42lb@3bar * 10.5 = 441cc/min@3bar
Blue: 378cc/min@3bar * sqrt(5bar/3bar) = <b>488cc/min@5bar</b>
Green: 441cc/min@3bar * sqrt(4bar/3bar) = <b>509cc/min@4bar</b>
RS4s have been measured at <b>481cc/min@4bar</b> (60psi)
Blue: 36lb@3bar * 10.5 = 378cc/min@3bar
Green: 42lb@3bar * 10.5 = 441cc/min@3bar
Blue: 378cc/min@3bar * sqrt(5bar/3bar) = <b>488cc/min@5bar</b>
Green: 441cc/min@3bar * sqrt(4bar/3bar) = <b>509cc/min@4bar</b>
RS4s have been measured at <b>481cc/min@4bar</b> (60psi)
02-06-2005, 05:51 AM
#7
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The blue tops at 5 bar flow a bit less than the greentops at 4 bar...
<ul><li><a href="https://forums.audiworld.com/s4/msgs/1899657.phtml">https://forums.audiworld.com/s4/msgs/1899657.phtml</a</li></ul>
