Hey guys,
Ive been doin some reading and maybe, just maybe one day ill get off 5psi,
I have 44# injectors, right now they are at 86% at 6000 rpms.
I also have a Walbro Intank pump.

How much boost can i up it to on this 6.0 before i run out of injector?
Im shifting it at 5500 btw.

 

I think you are not supposed to run them much past 85%. The smaller the injector the longer it must remain open to inject X quantity of fuel in X amount of time(RPM). At a certain point the injector that is too small will continue injecting fuel after the intake valve starts closing resulting in inconsistant fueling.

 

Ahh.. so basically im maxed out right now.
what about 60#s?

 

The problem is almost oposite with 60s. The larger high impedence injectors *can* be difficult to tune at idle (low pulsewidth). I haven't read about idle complaints with 60s in a while.

 

oh ok... well thanks for your help man.. look like ill be sticking with 5psi for awhile... got to pay for this 80E and other stuff...
i have a couple friends that can help me with the tune..

 

You can stretch your injectors out if you add any Alky kit and run 100% methanol. That is similar cost to upgrading the injectors and makes things more complicated. I'm sure you have a handle on the tuning, just read some of the threads on the EFI forum about idle tuning and tuning for large injectors.

 

Ive thought about the Meth injection.. but i dont need it anymore complicated than it is.. ive had enough problems with this dang truck so i dont need any thing else.
Im goin to just sit on 5psi for awhile and do some reading and emailing.
i figure 12 seconds at 5psi is respectable....

 

Log your injector duty cycle for the entire run, you will probably find you are under 80% IDC at 5500 rpm's. Also, if you add more boost you might only go over the 85% number for fractions of a second before you shift. Unless you have a dedicated drag truck it doesn't pay to go fight the tuning problems of larger injectors. With good tunning you should be able to get 7-8 lbs of boost and almost 10 lbs with meth. Remember 99.9% of the time you are running at 59 % IDC or less

 

I agree, but why strain them for even 1% of the time. It only takes 1 lean condition to fry a piston. Better to be safe than sorry. Plus i have been seeing more and more guys running the 60's with no issues idling at all. Hopefully i will be one of them soon.

 

With meth and 43 lb injectors I ran 12 psi on the old setup. You should be able to run 8 lbs easy, maybe even 10. I'm currently runnig 7.5 psi without meth. Gonna swap the 60s in a few days.