Testing Injector Pop Pressure in the real world

[Carbur8tr]

So I would be willing to bet that you will have issues with idle when you step up to the 350 bar.  I think the combination of the load as well as the higher canbus signal that will be required to make it stable is going to create swings like we are seeing with a couple of trucks now.  

 

I feel that my experience is unique in the fact that I am running a higher compression motor and pump so the idle swings and start issues seem to behave better due to those two things.

 

The idle data is awesome!  This is exactly along the lines of what I was thinking and shows the consistent ~2-3% offset with the higher pop pressures.  At this 2-3% I think it would be safe to say that the overall volume of fuel is slightly changed but negligible here.

 

So we are fighting two things here (in theory), combustion event and injection event. The atomization is better which could mean that the combustion starts sooner in comparison. So if the injection event is later, but combustion event is sooner we could see the two canceling each other out which is partially why no one has come forward and said that they could audibly hear a change in timing.  I know for me I honestly heard no difference and I suspect that there was not.

 

 

10 minutes ago, AH64ID said:

I do think that the shorter duration for the same fuel is a good thing thou. With CR's I really like overiszed injectors with less that stock duration as it doesn't require huge timing at rpms and all the fuel can still be injected. I have found lower EGT's for the same total fuel this way, all with less timing. 

 

Funny how this lines up perfectly with what we are seeing across the board with Nick's egts.

[Me78569]

This morning was the first cold, 7*f, morning with the stock bar injectors.  I can say that the 330 bar injectors started WAY easier, the truck was about as angry as I have seen it this morning.   The 7 x .009's acted about the same at -30*f.

 

injectors are back off to DAP to get repoped from 330 to 350 bar.   

[Mopar1973Man]

10 minutes ago, Me78569 said:

This morning was the first cold, 7*f, morning with the stock bar injectors.  I can say that the 330 bar injectors started WAY easier, the truck was about as angry as I have seen it this morning.   The 7 x .009's acted about the same at -30*f.

 

injectors are back off to DAP to get repoped from 330 to 350 bar.   

 

That being said, what pop pressure range would you suggest for my 7 x 0.0085 +75 HP injectors? This spring when I can swap over to the 1996 Dodge Ram 1500 I want to jump into this higher pop pressure I'm betting it will also improve economy as well with better atomization. 

[Me78569]

My theory is as injector size goes up pop pressure can be increased without neg results by more and more.  

 

7 x .0085 I doubt you would gain anything honestly.  I dont think I would personally mess with pop pressure if I was you.  

 

If we say that 7 x .012's like 330 bar ( still hard to say that)  and stock 7 x .007's are at 305 ish, then do a fuzzy math increase then you are looking at 310 bar or something for 7 x .0085 

[Mopar1973Man]

Remember stock injectors are 310 Bar. I think I'm at 300 bar now on the 7 x 0.0085 now. 

 

[Me78569]

lolol 250 psi is 17 bar.  bosch says that 310+17 is within spec.... so I guess 327 is the limit lolol

Id put them at 315 bar then

[Mopar1973Man]

This comes back to your 330 bar setup that you seem to like so much. Makes sense now. Being starting quality is good and smoke reduction is good too.

[kzimmer]

4 hours ago, Carbur8tr said:

which is partially why no one has come forward and said that they could audibly hear a change in timing.  I know for me I honestly heard no difference and I suspect that there was not.

 

I had mentioned when I first went to 365 bar that it sounded like my idle got a little noisier, a slightly more pronounced rattle. If you've ever heard an injector on a pop tester this makes sense. Pop any given injector at 280 bar, and then 365 bar, and they definitely sound different.

Edited January 16, 2018 by kzimmer
Spelling

[Me78569]

I reran the idle test with the stock bar injectors, I wasn't happy about the 120*f+ difference in egt in the logs it was too much to be correct.  this time the average egt was ~50*f more with 305 bar vs 330 bar, which is much more acceptible. weird thing is we see that 50*f difference in multiple steady state tests.   Rest of the stats are nearly the same.  Results are nearly the same. Conclusions are the same when I compare the 2 sets of injectors.

Edited January 16, 2018 by Me78569

[kzimmer]

I've personally noticed a very large fluctuation of EGT's during idling this winter. Nothing recorded. But with different combinations of ambient temp (and subsequent IAT), and ECT, I've seen it float around quite a bit. Not saying this is the case 100% for you, but it makes sense that it could be a little inconsistent.

[Me78569]

 guess I need to get busy @dieselautopower Can you comfirm that these injectors are the same nozzles as I was running before at 330 bar?  IE your guys just repopped what I sent back at 350 bar.

Edited January 27, 2018 by Me78569

[dieselautopower]

1 hour ago, Me78569 said:

 guess I need to get busy @dieselautopower Can you comfirm that these injectors are the same nozzles as I was running before at 330 bar?  IE your guys just repopped what I sent back at 350 bar.

 

 

 

 

Please check the yellow sticker in the upper right corner.  Pressure is written in pen over the build date.   If you have more questions please let me know.

[Me78569]

13 minutes ago, dieselautopower said:

 

 

 

 

Please check the yellow sticker in the upper right corner.  Pressure is written in pen over the build date.   If you have more questions please let me know.

yep it is,  sorry I wasn't clear are these the same physical injectors as the 330 bar setup, just repopped to 350(per the sticker)?   I hope they are because that allows me to compare pop without possible minor difference in the nozzle.

[Dieselfuture]

That's a good point Me.

[dieselautopower]

1 hour ago, Me78569 said:

yep it is,  sorry I wasn't clear are these the same physical injectors as the 330 bar setup, just repopped to 350(per the sticker)?   I hope they are because that allows me to compare pop without possible minor difference in the nozzle.

 

 

Is there any soot on the tip of the nozzle?  The flow should be the same even if they are new ones.  Flow is within 1% on the nozzles.

 

[Me78569]

They are used but clean.  Easy to see via discoloration on the tip.  

 

Good to know on flow.  We will see what I find

[dieselautopower]

Cool!  We polish up the shank on the nozzle but only clean the tips/holes very lightly.

 

should be +/- 0.03 lpm per set so thats only about 1-2% spread in flow across the set.

[Me78569]

350 bar injectors are in an WOW is all I can say.  When comparing the 305 bar to 350 bar I could EASILY run a tune starting %5 higher with the 350 bar injectors and still have significantly less smoke.  

Updating the first post now.  

[Me78569]

The 0-60 run of the 350 bar is up.  And they are squeaky clean, however as @jlbayeswas guessing the resulting 0-60 time is ~.5 seconds slower.    However I am ok with that, I think these injectors will settle down to ~340 bar in a few weeks and it will be about right. 

 

You will also note that EGT's are higher with the 350 bar, which is what @kzimmer found as well.   Looking at boost I might wanna check for a boost leak I guess haha.  I'll do that this week at some point and rerun the test if I find any.  However if we look at the idle stuff below you can see the loss in fueling as a result of higher pop.

 

I will say there is a defined lul right off idle now. 

 

 

 

Next is the idle compare, ignore the difference section I did not recreate it. 350 bar = green330 = white and 305 = orange. 

 

-Again here I see about a %5 lose in fueling if we compare fueling commands at idle from the 350 bar vs the 330 bar 
-EGT's are up as well. 

-note the ave/min/max section showing a significantly worse idle than the 330 bar.

 

Edited February 5, 2018 by Me78569

[dieselautopower]

Good work Nick!  Would like to verify there is not a boost leak.  After a few more days of running them and some MPG charting I will ask you what pressure you prefer and for what purpose/application.  

 

AWESOME write up!