duration/fuel pressure ?'s

[BIGRED08]

what is the highest duration should be set at? i don't know how much is to much. i know it was mentioned in another thread about to much duration would cause the injector spray pattern to start firing outside of the piston bowl. im currently at 3100us with no smoke and my egt's aren't getting over 1400*. can i keep adding? my fuel pressure question is, what is the lowest psi u want to see the fuel pressure actual fall off to when logging. mine drops to 20,600 psi and desired is at 22,xxx between roughly 2100-2500 rpm. pump picks up and runs fine after the initial pressure drop. any help would be appreciated. thanks

denny

 

[phale]

We have not ran much over 3200us, but I saw where nick at duramax/cummins tuner was running 3350 on the truck that did over 1000 with triples. At this point I don't know that we can honestly say how much is too much plus you have think about how much timing you are running and at what rpm you are turning to know for sure what the limit is. Your rail pressure should be ok, there will naturally be a difference in A/D on pressure as you are coming up in the band unless you have some really big pumps. The place to watch the difference is once the demanded levels out at your max pressure then you want as little difference as possible.

 

[BIGRED08]

ok, thanks phale. rpms don't get over 3500 (stock top end) with 45* (25*) max timing. truck runs real strong. just didn't know if i should go more without know if it was to much or not. i'll just stay around where currently at with us. as far as a/d, once the pump picks back up, it runs right with desired and sometimes actual is higher then desired. again i just wasnt sure if it should drop that much and if it would have any damaging effects on the injection system. thanks again for the help. still way new at all this. if anyone else has more #'s, i'd love to hear them for comparison. take care