I saw a car with stock internal and ported head ITR engine dyno at 178whp and the Hondata datalog show that the injectors are running over 100% duty cycle at above 7000rpm.

I really don't think a 290cc injector would have to run anywhere near 100% duty cycle in a 178whp engine. Is there possible something wrong with the 290cc injectors?

 

i am not suprised. I am running RC 370CC with only spoon cam, Power FC, max injector duty cycle is around 75%. Although you can' really compare like this but you get the idea.

 

Fuel pressure may not be high enough. My car dynoed a while ago with similar mods but with stock injectors but higher than stock FPR and it was not at 100% duty cycle. It dynoed 181 HP

 

Would a dirty injectors cause the higher duty cycle %?

 

Those duty cycle numbers on the Hondata tables are only the calculated/theoretical duty cycle values. The actual duty cycle can be different.

It's the rpm's that are killing the duty cycle. At higher rpm's they have less time to be OFF even if the allocated pulsewidths don't change that much or at all as a function of rpm.

 

I have 290cc injectors that are at 92% with 60 psi of fuel pressure and a motor making 190 whp.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AW &raquo;</TD></TR><TR><TD CLASS="quote">Fuel pressure may not be high enough. My car dynoed a while ago with similar mods but with stock injectors but higher than stock FPR and it was not at 100% duty cycle. It dynoed 181 HP</TD></TR></TABLE>
Raising the fuel pressure will not effect the duty cycle. It will effect the AF ratio however. Honda injectors were designed and intended to operate at high duty cycles. But at 100% duty cycle, the injector is constantly open.

 

Yes it will b/c it means that you can use less pulsewidth to hit the same fuel requirement.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RacerZook &raquo;</TD></TR><TR><TD CLASS="quote"> at 100% duty cycle, the injector is constantly open. </TD></TR></TABLE>

Well, really, it's only open for 25% of the time... 4 stroke engine and all...

-Chris

 

So is it normal to max out a 290cc injector on a 175whp engine?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ccfries &raquo;</TD></TR><TR><TD CLASS="quote">

Well, really, it's only open for 25% of the time... 4 stroke engine and all...

-Chris
</TD></TR></TABLE>
No, at 100% D.C. the injector is constantly on regardless if the valve is open or closed.

HP shouldn't be an indicator as to which injectors you should be using. HP changes from dyno to dyno. What's the AF ratio look like? Regardless if it's normal or not, you need new injectors.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IN VTEC &raquo;</TD></TR><TR><TD CLASS="quote">Yes it will b/c it means that you can use less pulsewidth to hit the same fuel requirement.</TD></TR></TABLE>
True, but if you raise the fuel pressure, you are not changing the duty cycle. You need a FMU to alter the injectors.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RacerZook &raquo;</TD></TR><TR><TD CLASS="quote">
True, but if you raise the fuel pressure, you are not changing the duty cycle. You need a FMU to alter the injectors.</TD></TR></TABLE>

Raising the fuel pressure does reduce the duty cycle. The higher pressure pushes more fuel through the injector for each pulse. Therefore the injector does not have to pulse as frequently (lower duty cycle).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RacerZook &raquo;</TD></TR><TR><TD CLASS="quote">
No, at 100% D.C. the injector is constantly on regardless if the valve is open or closed.

HP shouldn't be an indicator as to which injectors you should be using. HP changes from dyno to dyno. What's the AF ratio look like? Regardless if it's normal or not, you need new injectors. </TD></TR></TABLE>

Huh! I never knew that. That seems pretty inefficient.....

-Chris

 

Would a dirty injector make it run it higher duty cycle?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mafay2 &raquo;</TD></TR><TR><TD CLASS="quote">Would a dirty injector make it run it higher duty cycle?</TD></TR></TABLE>

If you're tuning the car based off of the WBO2 readings, and you have a slightly clogged injector you will be adding in additional fuel to compensate for an inadequate injector. However my 290cc/min injectors are pretty much maxed out at red line with my small amount of power, even when the injectors were fresh from being balanced and blueprinted at RC Engineering.

Austin

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Austin &raquo;</TD></TR><TR><TD CLASS="quote">

If you're tuning the car based off of the WBO2 readings, and you have a slightly clogged injector you will be adding in additional fuel to compensate for an inadequate injector. However my 290cc/min injectors are pretty much maxed out at red line with my small amount of power, even when the injectors were fresh from being balanced and blueprinted at RC Engineering.

Austin</TD></TR></TABLE>
What is the small amount of power that you are making?

Do you think the set up need bigger injector?


Modified by mafay2 at 5:52 PM 11/12/2004