Duramax Larger Injector Discussion

[Brayden]

Let's hear some more volker.. Are 10 hole nozzles available anywhere now? I'd be willing to try them out... Isn't EDM wire below .010" difficult to get?

How does having more holes affect the burn in the cylinder since there is less available oxygen between each "finger" or flame front? Is that a partial reason behind staggering the angles or is that just to shoot lower towards the bowl at higher injection timing advance?

Thanks,

Brayden

 

[malibu795]

How does having more holes affect the burn in the cylinder since there is less available oxygen between each "finger" or flame front? Is that a partial reason behind staggering the angles or is that just to shoot lower towards the bowl at higher injection timing advance?

Thanks,

Brayden

im going to see if i get this right...

every enteral combustion engine has a flame travel path. till all or most of the fuel is burned..

currently stock is 7 different paths..

going to 10 or more paths is increasing the areas by what ~50% easy?

this alowy more fuel to burnt at once and more complete in theroy

can you make more power... on papper yeah.. practicality... better results would be a direct factor of tunning and engine setup....

 

[Brayden]

The flip side to that is... having a larger flame front surface area leaves less oxygen between each front which may cause an incomplete combustion.. Volker.. where you at?

 

[ROGUE GTS]

Disclaimer: I know very little about diesel tuning and such, but am extremely educated in the gasser world.

Re the cummins having larger injectors. Of course they do, their displacement per cylinder is a good deal larger than ours.

As well, basic fluidynamics states that higher pressure doesn't have a constant rate of flow increase. As well, the size of the feed line/rail plays a big role in the flow through a given orifice at X psi.

As well, higher pressure will atomize the fluid better resulting in a more consistent and even flame front and burn. This, and to some degree the larger cylinder replacement very well could be the major factors in that notorious cummins rattle.

PS: lbz wristpins are pressed into the pistons? That's new territory for me. They are usually pressfit into the rod and free floating on the piston. Learning new diesel stuff all the time

 

[sweetdiesel]

So far I know just extrude honing / hydro grinding

besides you injectors is it safe to say that thats the norm for increasing injector flow

And how do you know with hydro grinding that every hole is the same size? Do they measure them after?

 

[malibu795]

PS: lbz wristpins are pressed into the pistons? That's new territory for me. They are usually pressfit into the rod and free floating on the piston. Learning new diesel stuff all the time

iirc all dmax wirst pins are free floating and not pressed

 

[McRat]

Disclaimer: I know very little about diesel tuning and such, but am extremely educated in the gasser world.

Re the cummins having larger injectors. Of course they do, their displacement per cylinder is a good deal larger than ours.

As well, basic fluidynamics states that higher pressure doesn't have a constant rate of flow increase. As well, the size of the feed line/rail plays a big role in the flow through a given orifice at X psi.

As well, higher pressure will atomize the fluid better resulting in a more consistent and even flame front and burn. This, and to some degree the larger cylinder replacement very well could be the major factors in that notorious cummins rattle.

PS: lbz wristpins are pressed into the pistons? That's new territory for me. They are usually pressfit into the rod and free floating on the piston. Learning new diesel stuff all the time

LBZ pistons have bushings pressed in the wristpin bores, LB7/LLY don't. Seems this is aggrivating the cracking problem, and perhaps is the reason for the <10,000mi cracked pistons. Looks like they overstressed some of the cast pistons when they pressed the bushing in.

 

[ROGUE GTS]

LBZ pistons have bushings pressed in the wristpin bores, LB7/LLY don't. Seems this is aggrivating the cracking problem, and perhaps is the reason for the <10,000mi cracked pistons. Looks like they overstressed some of the cast pistons when they pressed the bushing in.

Did they reduce the dia of the wrist pin to fit these bushings, or did they bore a larger hole in the piston? Seems just removing the material for the bushing may have weakened it.

 

[mde]

Let's hear some more volker.. Are 10 hole nozzles available anywhere now? I'd be willing to try them out... Isn't EDM wire below .010" difficult to get?

How does having more holes affect the burn in the cylinder since there is less available oxygen between each "finger" or flame front? Is that a partial reason behind staggering the angles or is that just to shoot lower towards the bowl at higher injection timing advance?

Thanks,

Brayden

So far I know there is no other supplier of 10/12 hole yet. The smallest hole I drilled was 0.002756" which is 0.07 mm.

Don't forget, diesel is not gas, diesel runs with excess of air, by the injection, your diesel vaporized in a burning mixture of diesel and air, which will burn with constantly pressure in the combustion. When there is not enough diesel that gives you the black smoke, but smaller diesel drops, better atomization, better vaporizing, better combustion.

Here just a basic how the diesel engine works compared to the Otto-motor

diesel:

Otto:

Staggering the angle: see here pic:

Caution: This is when the full injection takes place, integrate delay from boost current to opening of injector and until spray is complete, that takes a few micro second, how much? who know ...

I'm going to see if i get this right...

every antral combustion engine has a flame travel path. till all or most of the fuel is burned..

currently stock is 7 different paths..

going to 10 or more paths is increasing the areas by what ~50% easy?

this allow more fuel to burnt at once and more complete in theory

can you make more power... on pappier yeah.. practicality... better results would be a direct factor of tunning and engine setup....

The flip side to that is... having a larger flame front surface area leaves less oxygen between each front which may cause an incomplete combustion.. Volker.. where you at?

See above, BTW I'm here :hello:

As well, basic dynamics states that higher pressure doesn't have a constant rate of flow increase. As well, the size of the feed line/rail plays a big role in the flow through a given orifice at X psi.

As well, higher pressure will atomize the fluid better resulting in a more consistent and even flame front and burn. This, and to some degree the larger cylinder replacement very well could be the major factors in that notorious Cummings rattle.

I just say: Bernoulli's principle

besides you injectors is it safe to say that thats the norm for increasing injector flow

And how do you know with hydro grinding that every hole is the same size? Do they measure them after?

Thats not the norm, you know e OEM want to save money, now you have to decide for reaching emissions. We say: As cheap as possible, quality as necessary.

Yes, you have tools to measure the holes, also you drill the holes, measure flow, calculate time to ex.honing, extrude hone, measure again and you are done. flow = (NR of holes) x surface quality x radius on inlet x etc ...

Hope it helped

Volker

 

[McRat]

Did they reduce the dia of the wrist pin to fit these bushings, or did they bore a larger hole in the piston? Seems just removing the material for the bushing may have weakened it.

There might be a lesser cross-section, but it seems these pistons either crack immediately, or last a long time. This would indicate a variable, instead of fixed cause.

 

[McRat]

Thanks for pics Volker!! :rockon:

 

[mde]

You're welcome! Just hope, it helps someone!

Volker

 

[ROGUE GTS]

There might be a lesser cross-section, but it seems these pistons either crack immediately, or last a long time. This would indicate a variable, instead of fixed cause.

Sounds like craptacular QC from the raw materials supplier, or their casting company blows.

I just say: Bernoulli's principle

Yes... but really, how many people here do you think would have even the slightest idea what you meant if you said that?

It's like your doc saying you have a subdermal hematoma on your anterior deltoid... aka, you bruised your shoulder. :rofl:

 

[mde]

Yes... but really, how many people here do you think would have even the slightest idea what you meant if you said that?

It's like your doc saying you have a subdermal hematoma on your anterior deltoid... aka, you bruised your shoulder. :rofl:

I like the Dr language :angel:

 

[mytmousemalibu]

Day dreamin today...
Since I belive im pending another crapped injector. All of these LB7 injectors that have failed, logic tells me (besides a shitty design) these failures are in large caused by the high pressures they endure? I was wondering, If the max rail psi was slightly reduced would it help with injector longevity? I realize the psi's are key to proper atomization, burn, egt's, emisions, ETC. Now if it can be reduced a little to reduce strain but not to a point to noticably affect the above., and make up for the loss of mm3 per injection by increased pulsewidth? Since i am running bigger sticks (kinda like you guys running the PW up with stock sticks to get increased fuel as if you were running big sticks), do any of you think this is a plausable idea or barking up the wrong tree?
:feedback:

I really wish there was a cost effective cure for this crap! ONLY ligit complaint i have about the LB7!

 

[malibu795]

Day dreamin today...
Since I belive im pending another crapped injector. All of these LB7 injectors that have failed, logic tells me (besides a shitty design) these failures are in large caused by the high pressures they endure? I was wondering, If the max rail psi was slightly reduced would it help with injector longevity? I realize the psi's are key to proper atomization, burn, egt's, emisions, ETC. Now if it can be reduced a little to reduce strain but not to a point to noticably affect the above., and make up for the loss of mm3 per injection by increased pulsewidth? Since i am running bigger sticks (kinda like you guys running the PW up with stock sticks to get increased fuel as if you were running big sticks), do any of you think this is a plausable idea or barking up the wrong tree?
:feedback:

I really wish there was a cost effective cure for this crap! ONLY ligit complaint i have about the LB7!

i talked to to oddplanes the genuie pig for GM injectors... the GMs finding are the problem is NOT the INJ themselve but the 92 DCV that controls them .. they told him that ~50k was a good expected life span. and the newer version would hit ~100k span.

the sad thing is the truck were design for 7 year service life.....

 

[mytmousemalibu]

Every single last one that has failed on me has pissed fuel in the oil! They all from some part of the body, started pushing fuel out! Usually at the line inlet fitting where it goes into the body.

 

[mde]

Day dreamin today...
Since I belive im pending another crapped injector. All of these LB7 injectors that have failed, logic tells me (besides a shitty design) these failures are in large caused by the high pressures they endure? I was wondering, If the max rail psi was slightly reduced would it help with injector longevity? I realize the psi's are key to proper atomization, burn, egt's, emisions, ETC. Now if it can be reduced a little to reduce strain but not to a point to noticably affect the above., and make up for the loss of mm3 per injection by increased pulsewidth? Since i am running bigger sticks (kinda like you guys running the PW up with stock sticks to get increased fuel as if you were running big sticks), do any of you think this is a plausable idea or barking up the wrong tree?
:feedback:

I really wish there was a cost effective cure for this crap! ONLY ligit complaint i have about the LB7!

You are right with the high pressure and causing the cracks, but not alone. The problem by the CR-Systems are the pulsation in the whole system and injector. You get a lot of stress on the injectorbody and causes the crack, here a pick from a cracked body under full pressure:

 

[McRat]

We cracked a body on 1 LLY injector, but I think it was a fluke.

 

[malibu795]

can the bodies be made thicker? (LB7)