Walrbo 255 maxed out? Duel fuel pump ?'s - SRT Forums

Dasstrum · 10-02-2009, 09:09 PM

Ok, so my RC750cc injectors have maxed out at 93% duty on my Garrett 60 trim at 23psi.... time to upgrade fuel.

I am wanting to be able to run the turbo at 28psi on pump with 50/50 water/meth mix but am going to upgrade to some 1050's.

(Going to run 34psi on race gas)

I am also thinking about upgrading to duel fuel pumps because I don't know when my Walbro 255 will max at. I am thinking about getting this fuel pump hanger:

Full Blown Dual Pump Hanger 2003 + Dodge SRT4 - Modern Automotive Performance

With these injectors:
Fuel Injector Clinic 1050cc Peak & Hold / Low Impedance Drop In Fuel Injectors (SRT-4) - Modern Automotive Performance

I am wanting to know if anyone has tried this fuel pump hanger before and do I need to get it in order to run 34psi or even 28? Or will just the single walbro with bigger injectors be enough?

Thanks in advance!

nutz · 10-03-2009, 12:09 AM

your 750's should max that thing out, something is seriously wrong if your maxing out 750's ....stop and reevaluate the system

also try to pick injectors that AEM has evaluated for the EMS to save yourself a major headach

conroy9940 · 10-03-2009, 12:15 AM

do you have a return line? if not, get a return line and you won't max a 60 trim out with it.

Dasstrum · 10-03-2009, 07:55 AM

Yea, I do have a fuel return line.

So you are saying that on a 60 trim, I should be able to run 28psi on 750cc injectors?

Could it be that I haven't done a fuel pump rewire?

I'm just saying that the AEM is logging duty cycle during my pulls and it is showing 90-93% injector duty.

Here is another thing.... Before putting in my Brian crower stage 2 cams, I could run 24psi on the same turbo, same setup and my injector duty was like 75 or so. After adding my cams, I had to add a LOT of fuel up top in the MAP to get back to the same AFR's. (11.0 - 11.5)

aaronneon@RealTune · 10-03-2009, 08:48 AM

Pm sent

nutz · 10-04-2009, 03:31 AM

the injector duty cycle only reads from the injector PW on the table and dosnt take into account the % corrections, usually it reads lower than what it is with a boost comp (I dont know your tune)

true duty cycle can be watched manuelly its a calculation of time available usually arount a 17ms PW is 100% at around 7k rpm's, meaning the piston only has 17ms between intake cycles (not sure of the exact number but i can find it if ya want) and the injector is open 100% of the time (static on)

98rt_canadian · 10-04-2009, 03:42 PM

That dual pump hanger looks like a nice piece.

Dasstrum · 10-04-2009, 04:19 PM

Quote: Originally Posted by nutz

the injector duty cycle only reads from the injector PW on the table and dosnt take into account the % corrections, usually it reads lower than what it is with a boost comp (I dont know your tune)

true duty cycle can be watched manuelly its a calculation of time available usually arount a 17ms PW is 100% at around 7k rpm's, meaning the piston only has 17ms between intake cycles (not sure of the exact number but i can find it if ya want) and the injector is open 100% of the time (static on)

Ok, so how would I exactly test if the injector is actually hitting 93% duty cycle? Is there a easy way other than just monitoring the "Injector duty" parameter?

nutz · 10-04-2009, 06:43 PM

Quote: Originally Posted by Dasstrum

Ok, so how would I exactly test if the injector is actually hitting 93% duty cycle? Is there a easy way other than just monitoring the "Injector duty" parameter?

here is the equation and a good explanation Stealth 316 - Injector Duty Cycle Calculation

the EMS is fickle about measuring time since its based from the RAW and MB/SEC (it actually dosnt know what 1 is) it will not take into acount the % modifiers when reviewing the duty cycle on a fuel map, there is a parameter to log (dont know off the top of my head DC raw maybe) it may just be in your tune set up