Power FC Fuel System Qs , inj duty, pump, pressure, etc
10-31-01, 02:15 PM
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Fuel System Qs , inj duty, pump, pressure, etc
okay here is the deal, I want to upgrade fuel system, but do not really feel like I need new secondaries. WHat i sbest way to lower injector duty while keeping same stock injectors. Has anyone tried raising fuel pressure? does the PFC read this, and thus lower cycle times on injectoprs??
I have heard that only thing high-flow pump will do by itself is preventpressure from tapering off? however as I asked before if PFC doesn't know fuel rate, etc. then while it may be at 94% duty there is no fuel because pump can't keep up, or maintain pressure? so at which point you woudl nbeed upgrade. Can someone clarify all this for me.
Thanks guys
I have heard that only thing high-flow pump will do by itself is preventpressure from tapering off? however as I asked before if PFC doesn't know fuel rate, etc. then while it may be at 94% duty there is no fuel because pump can't keep up, or maintain pressure? so at which point you woudl nbeed upgrade. Can someone clarify all this for me.
Thanks guys
10-31-01, 04:16 PM
#2
I'll take a shot.
The only way to lower the duty cycle (while keeping all other parameters the same)is to get bigger injectors or raise fuel pressure. Yes, people have done this successfully and information is posted about it in various places. It's an inelegant way to go about it as you now have one more variable to mess up but it's cheap.
PFC knows nothing about your fuel pressure or pump flow rate so reprogramming would be necessary if fuel pressure is increased.
There should not be a problem with stock injectors and a stock pump. A higher flowing pump should not have any effect alone on fuel delivery unless the pump you are comparing it to was inadequate. If you have larger injectors, they can flow so much fuel that the pump cannot keep up and therefore pressure will drop with a corresponding drop in fuel injected. The pump needs to be able to maintain the desired pressure (and flow) at the maximum injector duty cycle you are using.
If you increase fuel pressure via an adjustable rising rate fuel pressure regulator, you must also consider that some pumps may be able to maintain the higher pressure at the expense of flow. That is, you need to get a pump which as the flow you need rated at the pressure you plan to use. This info is available from Wade here and explained much better probably:
http://www.wvinter.net/~flanham/wlanham/fuel/pumps.html
Hope that helps,
Alan Cross
Probably easiest to buy bigger injectors and send your PFC to XS.
The only way to lower the duty cycle (while keeping all other parameters the same)is to get bigger injectors or raise fuel pressure. Yes, people have done this successfully and information is posted about it in various places. It's an inelegant way to go about it as you now have one more variable to mess up but it's cheap.
PFC knows nothing about your fuel pressure or pump flow rate so reprogramming would be necessary if fuel pressure is increased.
There should not be a problem with stock injectors and a stock pump. A higher flowing pump should not have any effect alone on fuel delivery unless the pump you are comparing it to was inadequate. If you have larger injectors, they can flow so much fuel that the pump cannot keep up and therefore pressure will drop with a corresponding drop in fuel injected. The pump needs to be able to maintain the desired pressure (and flow) at the maximum injector duty cycle you are using.
If you increase fuel pressure via an adjustable rising rate fuel pressure regulator, you must also consider that some pumps may be able to maintain the higher pressure at the expense of flow. That is, you need to get a pump which as the flow you need rated at the pressure you plan to use. This info is available from Wade here and explained much better probably:
http://www.wvinter.net/~flanham/wlanham/fuel/pumps.html
Hope that helps,
Alan Cross
Probably easiest to buy bigger injectors and send your PFC to XS.
10-31-01, 04:53 PM
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i don't know anything bout the pfc, because it hasn't been delivered yet, but i do know when i conducted a search through out the site i found that for the $1000 that you will be spending on your fuel regulator, injectors and on your pump is worth it. it is considered a reliable mod when upgrading. i read your post over and over and if i am wrong about what you were asking, forgive me, but if you are modded i would strongly suggest upgrading fuel for the life of your motor. i'm just trying to help.
luigi
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11-02-01, 10:59 AM
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You can run rich and only really hurt performance.
If you want to maximize performance, plan on tuning after you make major changes...like adding a fuel pump, changing injectors, adding, new regulator.
Now you can tune by the seat of your pants, or on a dyno. The perference is on a dyno (with wide band o2).
The last thing you want to do is tune by the seat of your pants and remove any margin of error for detonation / running lean and really hurt your engine.
If you want to maximize performance, plan on tuning after you make major changes...like adding a fuel pump, changing injectors, adding, new regulator.
Now you can tune by the seat of your pants, or on a dyno. The perference is on a dyno (with wide band o2).
The last thing you want to do is tune by the seat of your pants and remove any margin of error for detonation / running lean and really hurt your engine.
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