injector flow rate question
02-10-2005, 10:12 PM
#1
Three Wheelin'
Thread Starter
injector flow rate question
Stock injectors flow 43 lb @ 3 bar. Or 37 lb @ 2.5 bar.
When gururacing sells 55 lb injectors (what I have) is this rating at 2.5 or 3 bar or other?
Thanks in advance!
When gururacing sells 55 lb injectors (what I have) is this rating at 2.5 or 3 bar or other?
Thanks in advance!
02-10-2005, 10:22 PM
#2
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3 bar
Originally Posted by mark944turbo
Stock injectors flow 43 lb @ 3 bar. Or 37 lb @ 2.5 bar.
When gururacing sells 55 lb injectors (what I have) is this rating at 2.5 or 3 bar or other?
Thanks in advance!
When gururacing sells 55 lb injectors (what I have) is this rating at 2.5 or 3 bar or other?
Thanks in advance!
02-10-2005, 10:32 PM
#3
Three Wheelin'
Thread Starter
Thanks jeremy. Now I found an old danno post saying the stock injectors flow 34.6 lb @ 3.0 bar. This works out to 31.6lb @ 2.5 bar, which contradicts the other info I have. Can anyone explain?
02-10-2005, 10:41 PM
#4
3.0 BAR like Jeremy says.
Where did this information come from?
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Stock injectors flow 43 lb @ 3 bar. Or 37 lb @ 2.5 bar.
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02-10-2005, 10:49 PM
#5
Three Wheelin'
Thread Starter
A book I have titled How to tune and modify engine management systems for a bosch injector ending in 951 and used for porsche. I just assumed it was ours, maybe i was wrong. Can anyone confirm the stock flow rate?
The reason for all these questions is I am trying to run 55lb injectors @ 3 bar fuel pressure, and I need to make chips for it. I am trying to calculate the pulsewidth modifications that need to be made without guess and check to save time.
What is the equation for total injector flow in weight? Including pulsewidth, pressure, and injector flow rating? Does such a thing exist?
The reason for all these questions is I am trying to run 55lb injectors @ 3 bar fuel pressure, and I need to make chips for it. I am trying to calculate the pulsewidth modifications that need to be made without guess and check to save time.
What is the equation for total injector flow in weight? Including pulsewidth, pressure, and injector flow rating? Does such a thing exist?
02-10-2005, 10:59 PM
#6
Bosch P/N 0 280 150 803 should be the 944 Turbo PN, 40.1 lb/hr at 45psi is the number that I find, which is about 36.5 lb/hr at 2.5 bar. Not too far off.
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02-10-2005, 11:00 PM
#7
Why not run 72s with the stock 2.5bar regulator?
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Trending Topics
02-10-2005, 11:29 PM
#10
Three Wheelin'
Thread Starter
The whole problem is that my map box broke, so I went back to the stock afm. So I need to burn myself some chips. I have calculated that with 55 lb injectors and 3 bar of fuel pressure i need to decrease all pulsewidths by 47 % to equal the flow of 31.6 lb injectors at 2.5 bar. Can anyone confirm this?
02-11-2005, 06:17 AM
#11
Race Director
Mark, the 55# rating on the injectors are measured at 3.0bar. If you're going to be running 2.5-bar, then you have to scale those injectors down to 2.5-bar, or about 50# per hour. Then take the ratio between the injectors 50:34.6. However, this only works for 100% duty-cycle max-flow rates. At percentages of that maximum, say 25%, 50% and 75% duty-cycles, different injectors from different manufacturers actually flow different amounts. The variations are actually over 10-20% on the extreme ranges.
Don't worry about all this math, the latest chip I sent you is programmed for 55# injectors only. Each click clockwise on the FQS adds 4% enrichment. The master-AFM setting in the MAP box should be set to 0% adjustment.
Don't worry about all this math, the latest chip I sent you is programmed for 55# injectors only. Each click clockwise on the FQS adds 4% enrichment. The master-AFM setting in the MAP box should be set to 0% adjustment.
02-12-2005, 02:06 AM
#14
Three Wheelin'
Thread Starter
Danno, there is no master afm setting since I am not using the map box anymore. Its at link getting repaired, looks like a bad processor.
I did the calculations out, and found that to make stock chips work with 55lb injectors and 3 bar of fuel pressure a 37% decrease is needed across the fuel maps. That is multiply the current value in each cell by 0.63. I tried this, and it was DEAD ON. I was very suprised as my calculations usually dont work.
So I am good to drive until my link box is repaired, hopefully soon. I am still waiting to try the water injection w the new 25 psi chips, but I am not in a big rush until spring. Thanks for the help everyone!
I did the calculations out, and found that to make stock chips work with 55lb injectors and 3 bar of fuel pressure a 37% decrease is needed across the fuel maps. That is multiply the current value in each cell by 0.63. I tried this, and it was DEAD ON. I was very suprised as my calculations usually dont work.
So I am good to drive until my link box is repaired, hopefully soon. I am still waiting to try the water injection w the new 25 psi chips, but I am not in a big rush until spring. Thanks for the help everyone!
02-12-2005, 02:09 AM
#15
Three Wheelin'
Thread Starter
951kid, smaller injectors are no more accurate unless for some reason the big ones are not suited for the necessary range. As in they are so big that they the pulsewidths are so small at idle that there is no time to open and close the injector fully. Otherwise, not a problem. It is best to have the biggest injectors that will still allow the car to idle, that way you dont push the duty cycle up too much under boost. That is, unless you have twin injectors per cylinder. Then you can have 2 small ones.
