Hey all,

My original injectors were 900 psi down, so I bought Cummins reman units. Unfortunately these pop at 3800-4000 psi. Stock is listed at 3625 psi.

I advanced the timing to compenstate for the higher pop pressure, but that shows up as turbo lag. If I retard the timing, the turbo lag disappears, but so does the top end and fuel economy.

I am wondering if I have the injectors reshimmed to 3625 psi if I can get a better middle ground - some timing advancement, good turbo performance, good fuel economy.

Thanks,
Brian

 

theres a couple good timing threads here in the first gen section you might wanna search and take a look, could maybe help you a bit. As for your question about getting them reshimed for lower pressure, I really have no clue have to let someone else chime in. But you could also compensate for the bad spool up by getting a smaller exh housing. If you had your signature filled out better we would know what you have.

 

My truck is "stock". Except for these "stock" reman injectors that aren't shimmed to pop at the stock pressure :-)

-brian

 

you could use a smaller housing to compensate for the lag you get with the timing advanced but it also depends on what the truck will be used for as smaller housings can get restrictive

 

I really don't have any desire to tune the truck and change expensive parts that still work.

I bought stock injectors figuring I wouldn't have to deal with it anymore.

Turns out these stock injectors are firing with 2nd gen pressure making me think someone screwed up somewhere!

-brian

 

the exh housing is something that doesn't wear out they also don't cost too much depending on what your want. if you think they screwed up somewhere then just take them back and tell them you want them at the proper pop pressures

 

You are correct, the pressure setting on them is a bit too high....too high because it is going to work the daylights outta the injection pump.
The original nozzles had a popoff of about 245 - 250 bar (just either side of 3600 psi.)
The upgraded pressures your running take the popoff to 262 - 275 bar....too high. I've tested and run injectors at the 275 bar setting and it is pretty tough on the pump..this is based on the "working sound" of the pump...they get real 'metallic' sounding...
Your ideal/max pressure is about 265 bar or roughly 3770.988 psi.
I'm convinced that a basically "stock" VE pump should work well and reliably with pressures up to about 3700 - 3800 psi and no more......at least that's as far as I'd ask my pump to work without a gift certificate to a pump rebuilder shop..

pb....