duty cycle

[FOTIS84]

my dc is 120 % at wot after 7000rpm.how can i reduce it a little without changing injectors;add something to injector open time;i have two squirts simultaneous,can i change to alternating;

[Bernard Fife]

F84,

Go to two squirts alternating, that will help the duty cycle by one opening time per cycle.

You certainly don't want to add anything to the opening time, if anything you would like to reduce it. However, the actual opening time is whatever it is, and changing the setting only means you have to retune and will end up with the same pulse width (and duty cycle).

If you engine is overly rich you can lean it slightly.

You can also increase you fuel pressure, there's a calculator here: http://www.megamanual.com/v22manual/minj.htm#size

Lance.

[FOTIS84]

THANKS for your answer but i have another question.why i have 120%?the limit must be 100%.is it possible?

[stevemgb]

The documentation suggests 85% as a "safe" limit as the injector behaviour is unpredictable after this.120% is showing how much fuel is required and not how much is added.When I first squirted my car I miscalculated the fuel requirements and had 100% duty at 80mph,after which it ran leaner and leaner.More or bigger injectors are the easiest answer,to me at least.Steve

[FOTIS84]

finally i bought bigger injectors.i had 149cc/min and now i have 189cc/min.is there any rule for conversion my old map to a new basic map;

[TT350chevelle]

Your old map should be very close once you change your req fuel to reflect the new, larger injectors.

Brad J.

[FOTIS84]

i have changed the req fuel from 7.25 to 6.02.the result was good but rich again.i needed to reduce 10%.now everything is fine and my dutycycle at wot is maximum 85%.