Testing Injector Pop Pressure in the real world

[kzimmer]

Very interesting. There seems to be a plateau that occurs somewhere between 330 and 350 bar. A lot of this info jives with mine. I never recorded idle state rpm in gear like you did, but I saw the same thing with the naked eye.

[Me78569]

I am still a bit shocked as to how clean these things run.  Towed the horse trailer yesterday, no egt issues, I couldn't even make it smoke if I wanted to at this point.  

 

 

I didn't have a chance to log anymore since I left the trailer connected last night.  I will try to do the 55 mph testing and the od lugged pull tomorrow.  I think cruise egt's will be up and I think spool time will be up as well, maybe a touch faster than stock bar.

[Me78569]

well I am not sure where my log went for 305 bar at 55, but we do have the graphs stll.

 

 

Here is 330 vs 350 bar at 55 

 

Here is 330 vs 305 bar 55

 

 

 

we can see that really the perks from 330 bar went away at 350 bar.    EGT's are up again with 350 bar.  

 

Given what I have seen so far, I think 330 bar is about the limit for pop on the 7 x .012's I am running in terms of overall perks.  The 350 bar injectors do run a fair bit cleaner than the 330bar and WAY cleaner than the 305 bar.   But the 350 bar fueling about %5 less whereas the 330 seem to fuel less than %2 less.

[Me78569]

@dieselautopower  

 

So after a few days I think 330bar with the 7 x .012 vco's is the best overall setup, HOWEVER after a few weeks the 330 bar's settled some and were worse than they started.  same for the 305 bar, they got really smokey with no tune changes after a few weeks.

 

The 350 bar run stupid clean ( I REALLY like that).  my hope is that after a few weeks the pop pressure settles down to 340ish bar and they act like the 330 bar did when I first tested them.  

 

I am too lazy to swap injectors again back to 330 bar. the 350 bar dont really have a huge draw back for my, but generally speaking I think they are too high for most.  

 

 

Without testing to see where pop lands after a few months I dont think you should be selling pop that high to start to the masses.   I dont see a real issue with 350+ bar, but the performance and perks go away at 350 bar.  

[Dodgeih]

Seems that I have nailed mine starting at 340 bar. Sorry I haven't tested much lately been dealing with tons of work (just bought a bedliner business) and to worried about fixing my fuel leak, that I finally got fixed yesterday ? thank god. Once the weather clears up I will get videos and data! 

[Dieselfuture]

1 hour ago, Dodgeih said:

Seems that I have nailed mine starting at 340 bar. Sorry I haven't tested much lately been dealing with tons of work (just bought a bedliner business) and to worried about fixing my fuel leak, that I finally got fixed yesterday ? thank god. Once the weather clears up I will get videos and data! 

Oh man that's a good gig badlining things, congratulations. I've seen this stuff on just about anything including work boots. What product will you use, I heard xline is better but can be slippery vs that other more rubbery stuff, can't think of a name. 

Edit: oops sorry Nick that wasn't related to Pop pressure you can delete my post if you wish. May I say one more thing, would be safe to say if you wanted 330 bar have them set it at sat at that 340 like posted above and hope that they settle to 330 and stay there.

Edited February 8, 2018 by Dieselfuture

[kzimmer]

Mine settled from 365 Bar to 350-355 Bar. Seems like a good bet that you'll drop 10 Bar after setting. Makes me wish I reset mine to 340 instead of 330.

[Me78569]

whats one more time popping?

[kzimmer]

5 minutes ago, Me78569 said:

whats one more time popping?

 

Ugh... Tempting, haha. Every time I work on something on this truck without fixing an oil leak I feel guilty.

 

Can you force your truck to stall? At 365 bar I could force a stall fairly easily. The odd time by accident. At 330 I can't even force one, no matter what I do. Maybe once, in an extreme situation that's almost impossible to recreate. Especially since the pop may have settled to 320ish bar anyway.

[Me78569]

I have tried a few times but have been unable to get it to stall yet. rpms get pretty low, but the engine recovers pretty snappy.

[Me78569]

Found 3 major boost leaks....  Gonna have to rerun the 0-60 I am betting EGT's will be down, boost will be up.

[Me78569]

@kzimmer  temps got down to ~0*f last night.  the truck was noticably harder to start than the 330 bar setup.  Dunno if I will see colder this winter or not, but I could see issues getting it to fire at ~ -20*f and below.

[kzimmer]

13 hours ago, Me78569 said:

@kzimmer  temps got down to ~0*f last night.  the truck was noticably harder to start than the 330 bar setup.  Dunno if I will see colder this winter or not, but I could see issues getting it to fire at ~ -20*f and below.

 

Excellent! Well not good that your truck is starting hard, but good that we are seeing common data.

[beren]

How to these higher pop pressures affect the VP44? I realize it's a very high pressure unit, but do you t think the extra fuel pressure in the lines after a pop will have a negative effect on it long term?

[jlbayes]

1 hour ago, beren said:

How to these higher pop pressures affect the VP44? I realize it's a very high pressure unit, but do you t think the extra fuel pressure in the lines after a pop will have a negative effect on it long term?

 

Eventually yes that will happen. Opening pressure was determined by Bosch for a reason. Will it happen to anyone in the life of the pump or the truck? Who knows.

[Mopar1973Man]

1 hour ago, beren said:

How to these higher pop pressures affect the VP44? I realize it's a very high pressure unit, but do you t think the extra fuel pressure in the lines after a pop will have a negative effect on it long term?

 

You have to remember at WOT throttle the VP44 creates like 20,000 PSI (1,378 Bar).

[beren]

Yeah but how often is it at WOT? It's about a 600 PSI higher baseline pressure behind the VP to go from 305-350 bar. I was just wondering if anyone thought it would wear it faster

[Mopar1973Man]

Stock is 310 bar (+/- 250 PSI) which makes it 297-327 Bar which is allowed. 

 

Edited February 12, 2018 by Mopar1973Man

[Me78569]

@beren  Bosch specs 297- 327 bar as acceptible.  The only thing that i could see wear faster is the nozzle seat.  The lines could care less, I also doubt the plungers in the pump care.  The pump is already overcoming that extra pressure every stroke, remember the pump builds pressure faster than the tip can flow it.  So there is always more pressure than pop pressure in the lines / being generated.

@kzimmer  I almost wonder if we need more timing when cold if pop is high like that.   It stands to reason the pop delay would be highest at low rpms, then add cold fuel to the mix and we might not be getting enough timing to fire it off.

 

Edited February 12, 2018 by Me78569

[kzimmer]

8 hours ago, Me78569 said:

@kzimmer  I almost wonder if we need more timing when cold if pop is high like that.   It stands to reason the pop delay would be highest at low rpms, then add cold fuel to the mix and we might not be getting enough timing to fire it off.

 

Either that or more fuel. I always thought retarding timing aids in cold starting (to a limit of course). When I still had the 7x.014's in, I noticed cold starts improved when I upped them from factory to 340 bar. 7x.013's at 365 bar were brutal. Down to 330 bar and it's not bad. Except I still have a problem where the longer I leave the truck, the harder it starts. Issue is compounded with colder weather. Gotta be air getting in somewhere but I don't have a clue. No visual fuel leaks.

 

Assuming I can resolve my starting issues, I think these 7x.013's will be happiest at 330-340 bar. I'm likely going to take them out one more time, set to 340 bar, and put on a better set of copper o-rings. These were generic from a local parts store and might not be helping the situation. I measured them and they seemed ok... But meh. Good to rule it out.