Thread: Understanding fuel duty.
07-11-2014, 01:37 PM #1
- Join Date
- May 2013
Understanding fuel duty.
If fuel duty is at 100% and you cannot hit the target AFR (still too lean), will increasing the fuel pressure help?
I realise that blanket raising the fuel pressure will screw with all the other AFR's, but I can take fuel out at those places.
So assuming raising pressure would work, when should you increase injector size and back the pressure off again?
Running stock #48's at 59psi (cause I can hit 58 on the dial!!)
What is considered good practice for injector duty %?
Finally, which injectors would help me with my mod level and not screw up my idle?
Trying to learn, not just get a part number.
Last edited by tornado34; 07-11-2014 at 01:57 PM.
07-11-2014, 02:29 PM #2
Idle quality is is not a problem on the VT11 injectors. I run them on a stock motor. My idle fuel pressure is 60 PSI. At WOT, it drops to about 58 PSI.
07-11-2014, 05:58 PM #3
07-11-2014, 06:39 PM #4
VT11's here. No drivability concerns to report.
07-11-2014, 06:50 PM #5
80% DC at 20 psi and 8900rpm here.
Stock pump, riva rrfpr, set to static pressure. Turbo.
IMO if your at 100% DC at 58-59 psi you need to upgrade the injectors and or check fuel pressure at wide open throttle.
Running 90% or above can be dangerous when the weather cools back down.
Last edited by hotbird; 07-11-2014 at 09:30 PM.
07-11-2014, 07:12 PM #6
Keep in mind that you need to have the base tune in your ECU set up for the opening time of the injectors. Each brand has somewhat different caricaturists. There are settings in the ECU that need to be set.
Note that a 1000cc in brand Y can require very different settings for a 1000cc in brand Y. The spray pattern can also be very different.
07-11-2014, 08:39 PM #7
07-11-2014, 08:47 PM #8
What fuel pump is in use? There was great debate on different pumps and the use of a relay.
07-11-2014, 08:55 PM #9
why would bigger injectors raise fuel consumption
you need to have the correct tune for every injector
the bigger injectors are needed if your injectors are in the 90s% duty cycle
injectors run there can misfire or lock up
also idle will not change if you have the correct tune
v-tech has tunes for their 1100 injectors (probably actually only 950cc)
you should never change injectors with out changing the tune in the ecu
07-11-2014, 08:55 PM #10
I came from a 35 year road racing background when I purchased the RXPX.
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